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Strategies for Enhancement of Food Production Part 2

Sericulture.

Sericulture is the breeding and management of silk worms for the production of silk. It has been practiced in
India since second era or century B.C. The silk which is produced by silk worm is of a valuable natural protein fibre.
Silk worms are the larvae of silk moths. The rearing of silk worm for the production of silk is known as sericulture.

(i) History of silk : Historical account of use of silk and rearing of silk worm eggs, larvae and cocoons are
available from china. It was Lotzu the empress kwang-Ti who for the first time discovered the silk thread and its
source the silk worm cocoon. The technique of sericulture was kept as a secret by the chines people. In about 550
B.C. The sericulture technique was diffused to European countries. The available mythological literature deals with
facts rearing the use of silk in ancient India. By about 1000 A.D. the sericulture was in practice in China, Europe
and India, China was the leading country in this field.

At present the sericulture is practiced in China, Japan, Korea, India, Brazil, Russia, France and Italy. Some of
the south east asian countries. China is topmost country producing some 48% cocoons and 40.9% of row silk. Next
biggest silk producing country is Japan, India is placed in third position as for as the production of silk in term in
quantity is concerned.

(ii) Silk in India : As far as silk as a fabric is concerned it is a matchless fabric second to none. Therefore, silk
garments have been a favourite choice since ancient times. Use of silk clothes finds its mention from pre-historic
period. There are description of use of silk clothes from vedic period. In Ramayana and Mahabharat period the silk
clothes adored the bodies of royal princess, prince, kings and queens. It attire of the rich people. The silk clothes
were used to the superiority of social and economic status. It was given in gifts by rich people and royal families.

In the medieval period the silk was a recognised commodity of commerce. The silk clothes and raw silk were
imported from China and Japan. Later on it was also imported from Europe. By the Moghul period India had a
rich heritage of silk clothes. The silk was imported as raw silk. It was spun into silk thread and silk clothes were
woven in handlooms silk clothes became almost a craze among royal families and rich persons. A number of such
looms were in operation in Banaras, and different parts of Uttar Pradesh, Kashmir became centres for the
production of cocoons and rearing of silk worm. Sporadic silk textile centres were also present in South India. It was

cin 1905-1906 that a scientific investigation in the field of sericulture was undertaken in India by the Indian Institute

of Agricultural Research at Pusa, New Delhi. It was Lefroy who conducted research on the silk worm and
potentialities of silk production in India. A series of exhibitions were organised to popularize silk and attract the
attention of scientists and industrialists as well towards sericulture in India.

By 1910 India started regular production of raw silk. The rearing of Bombyx mori and Autheraea species was
undertaken. Silk textile industry was finally established in Kashmir, U.P. and Karnataka. Silk garments were
exported by this time. Silk clothes from Bengal, Banaras and karnataka were famous even in the European
markets.

(iii) Silk in Modern Age : Sericulture as well as silk industry is firmly established in India. India at present is
the third biggest country in the field of silk production and only next after China and Japan.

The reasons for the poor growth of sericulture in India were:

(a) High cost of production.

(b) Low yield.

(c) Poor quality of raw silk.

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But the recent efforts by the Government of India and various state governments such as research in

sericulture and training in sericulture technique, development of silk worms marketing facilities and cultivation of

plants, e.g. Morus indica or shahtoot Norus alba or 'Toot' castor sal etc. Central Sericulture Station, Berhampore,

Central Research and Training Centre, Mysore and Ranchi have been established. Various states have undertaken a

programs of research, training and plantation of host plants under their rural development programs. As a result of

these efforts new varieties of mulberry plants have been developed and are being cultivated. These varieties are

called as M 2 and M5 varieties. They gave 100% increased yield of mulberry leaves upon which the silk worm feeds.

Different varieties of silk worm, Bombyx mori and Autherea have been developed which can be cultivated in

various states. Existing races of silk worm are being improved Bivoltine species are being developed. Low

production and higher yield have been achieved as a result of these efforts. India is producing 4200 metric tons of
silk per annum (1980). This figure is even higher at present. India is exporting some 25% to 30% of its total silk
production in the form of silk garments and fabrics. Karnataka is the biggest silk producing state followed by Jammu
& Kashmir and Tamil Nadu, Madhya Pradesh is also emerging on the scene of silk production. India is producing
China silk, Tasar silk or Cosa silk, Muga silk and Eri silk today.
c(a) Family – Bombicidae
Largest silk producing state of India is Karnataka.

The zoological name of common silk worm is Bombyx mori

or

Silk is obtained from Bombyx mori.

(iv) Systemic position :

Phylum - Arthropoda

Class - Insecta

Order - Lepidoptera

Family - Bombicidae and satarnidae

(1) Bombyx mori : It is known as China silk worm or mulberry silk worm. It is native of China. It has been
fully domesticated for the production of silk. It produced quality of silk which is white silk or yellow silk.

(2) Other species of Bombyx are B. texior, B. fortunatax and B. meridionles. They are well Known in our
country.

(b) Family – Saturnidae : Antheraea paphio - It belong to the family saturnidae. It is widely distributed in
india in the states of Karnataka, Tamilnadu, Madhya Pradesh, Uttar Pradesh, Bihar and West bengal. It feed on and
fig plants. Its favourite host plant is Arjun (Terminalia arjuna) sol (shorea robusta). It has been recently domesticated
for sericulture. It produced Tassar silk (kosa silk.)

(v) Habit and habitat : The silk worm distributed in temperate regions are diapause type i.e. they remain
inactive for some time in winter. The silk worms inhabiting some tropical regions. Are of non -diapause type they
are holometabolous. The life cycle stages include egg- larvae-pupa and imago

(vi) Adult Moth : The moth measures about 25 mm in length and wing span measures about 40-50 mm in
width. Female moths are larger than male moths. In general univoltine races are of larger size that multivoltine.

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It has whitish colour with gray marks on wings in some races. The body is divisible into head, thorax and
abdomen. Head contains a pair of eyes and a pair of pectinated antennae specially larger in males. Thorax contains
three pairs of legs and two pairs of wings covered with scales. Female moths are without mouth. The abdomen is
plump. Digestive system is poorly developed. The excretory system consists of three pairs of malpighian tubules
present at the end of mid gut. The reproductive system is very well developed in females and males.

(vii) Life History

(a) Copulation : The copulation lasts for about three hours. During copulation the male sits over the female

and holds her with the help of chitinous hooks. Both the moths acquire back to back' position. The female has a

scent gland at the terminal end of the abdomen, which secretes volatile secretion called pheromones to attract the

male.

(b) Egg : Copulation is immediately followed by egg laying. The eggs are small, oval and creamy white in
colour. They become darker as they become older. Each moth lays about 500 to 2000 eggs. The eggs are glued to
the under-surface of the leaves of the host plant.

In univoltine egg's hatching takes place after one year. In multivoltine it takes place after 10-12 days.

(c) Larva : After hatching a larva comes out of egg. It is called as caterpillar larva. It is 1.2 mm to 3 mm in
length depending upon the race. It has grey or creamy-white colour.

The body of larva is divided into head, thorax and abdomen. The head consists of three fused segments.
Mouth parts are biting and chewing type or strongly mandibulate. A pair of antennae and six pairs of are also
present on head. Mandibulate mouth parts are used to cut and chew the leaves. The thorax consists of three
segments. Each segment contains a pair of legs with recurved hooks. They are used for locomotion and
manipulation of food during feeding. The abdomen consists of ten segments. The last and tenth segment is poorly
developed. Five pairs of pseudo legs are present on 3rd, 4th, 5th , 6th and 9th abdominal segments. These are used
for locomotion.

Silk is the secretion of salivary gland

• Silk gland : Among other visceral organs larva contains well-developed paired glands called silk glands.
When fully developed, these glands
becomes five time larger than the length of

cthe larva and there weight becomes 2/5th
of the total body weight. Each gland is

divisible into an anterior, a middle and a

posterior region. The middle portion is

broad and is called as reservoir. The

anterior and posterior parts are narrow.

The anterior parts of both the silk glands

are united to form a common duct which

opens through a spinneret situated on

hypopharynx. The posterior coiled part of

gland secretes a protein called as fibroin. It

is covered and surrounded by sericin

secreted by middle part. A pair of Mature Caterpillar
accessory glands or the glands of felippi Life history of (Bombyx mori)

open the duct of silk gland. Its secretion

probably lubricates the silk. The silk is secreted in liquid form, which solidifies on coming in contact with air.

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The larva is voracious eater. It feeds on mulberry leaves. It may ingest about 30,000 times more than its body
weight during its complete larval period and increases about 10,000 times more than the body weight of its body
from the time of hatching. As the larva grows, it sheds it cuticle. This is called as moulting. The form of larva
between two successive moults is called as instar. The larva has five instars:

Ist instar - from hatching to Ist moult
IInd instar - between Ist moult and IInd moult
IIIrd instar - between IInd moult and IIIrd moult

IVth instar - between IIIrd moult and fifth moult

Vth instar - between fifth moult and pupation

A fully-grown larva of Vth instar attains the length of 7.5 cm. It stops feeding and starts spinning the cocoon. It
secretes silk thread from its spinneret and forms covering in which it encloses itself completely. It takes about 3-4
days to spin the cocoon.

(d) Pupa : The cocoon consists of silk thread. The enclosed immobile larva in the cocoon is called as Pupa.
The pupal stage is non- feeding and non-mobile. It remain & inactive. But the internal organs undergo drastic
changes collectively called as metamorphosis and transforms itself into imago.

(e) Cocoon : The cocoon is white or yellow in colour. It is made up of about 1000-1200 meters long silk
thread. The thread is wound around the cocoon is concentric circles. The weight of one cocoon is about 1.8 to 2.2
gms. The pupal period lasts for about 10 to 12 days. Alkaline fluid which makes the threads of cocoon to be soft.
Soft threads are cut open by the imago. A young moth comes out of cocoon.

Factors influencing the life cycle : The life cycle is influenced by the external environmental factors, such
as, temperature, humidity and light. These factors control the growth of the larvae and also the quality of silk
produced. The growth and moulting is controlled by hormones called juvenile hormone and ecdysone.

(f) Fertilization : After the moths emerge out from cocoons one female from one lot is kept with the male
from another lot. They form pair and copulate. After copulation is over separated and kept with female of another
lot. Thus one male can be used to fertilize at the most two females of different lots.

(g) Egg laying : After fertilization the female starts laying eggs. Egg laying is completed in about 24 hours.

cThe laid eggs are called seeds. The eggs are transferred in sterilized and tray stored at 4°C.
(viii) Composition of silk : The silk is a secretory product of silk glands of the larva. Silk is composed of
proteins. It consists of an inner part made up of fibroin protein (C30 H46 N10 O12) and is covered with an outer
envelope made up of sericin protein (C30 H40 N10 O12). The silk thread contains 75-80% fibroin and 20-25% of
sericin,

(ix) Sericulture industry : Sericulture industry involves three steps, (a) mulberry cultivation (b) silkworm
rearing and (c) silk reeling.

(a) Mulberry cultivation : Mulberry is the only food of silkworms. Mulberry plants come up in any soil and
in any climate. It is propagated by cuttings. The land is ploughed well 6 or 7 times in April-May and manured at the
rate of 2 to 25 tons per hectare. Small pits are scooped out 2 or 3 cuttings are lanted in pit. Each cutting should be
20 to 23 cm in length with nodes. When the plants grow too high they are cut back and this is known as pruning.
Pruning. Pruning will help in the production of a new flush of leaves. The plants can yield for 12 years. Every year
6 to 8 crops of leaves can obtained and the average yield per hectare is 25 to 30 metric tons of green leaves.

Species – morus indica, morus alba.

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(b) Silk worm rearing – Silk worm rearing needs the following:

• Rearing house

• Rearing trays and stands

• Chandrikes as support to build the cocoon.
The hybrid eggs are obtained from the sericulture department. The larvae are hatched from the eggs. The
newly hatched larvae are brushed into rearing trays and tender, chopped are provided to them. Fresh leaves are
offered 3 to 6 times a day and the old unconsumed leaves are cleaned periodically. From the fourth instar onwards,
whole fresh leaves can be given. The consumption of leaves by the larvae increases with their age. At the end of the
final instar, fully grown mature larvae are transferred from the rearing trays to chandrikes and allowed to build
cocoons. Cocoons are then collected and marketed.

Grainage Management : This is done to provide good quality of seed to rearers and also to maintain the
original quality. With this air grainage management is done by taking of caterpillar stage. They are protected from
diseases and are provided good nutrition. An initial selection is made by observing pupal mortality rate. If the
mortality rate is high, then such cocoons are rejected and are not kept for seed production. If the mortality rate is
sufficiently low, their only such cocoons are selected and kept for seed production. The selected cocoons are kept
for mass emergence. Before doing so the cocoons are examined and sexed. Males are kept separately and females are
kept in separate lots.

(c) Hatching : The process by which larvae come out of the egg is known as hatching. After hatching larvae
start eating mulberry leaves. The success of sericulture depends on the supply of good quality of mulberry leaves;
therefore the hatching must coincide with good mulberry season. Now a days controlled hatching is done by placing
the eggs in low temperature. The eggs are turned and moved with the help of a feather. Now -a-days the eggs are kept
in mulberry leaves in sterilised trays. If hatching is to be delayed or controlled, the eggs are kept in separate trays and
refrigerated for a suitable time.

The caterpillars which hatch out are kept in separate groups according to their age.

(d) Supply of seeds to rearers : Under this step the are supplied with seeds. The seeds are of two qualities,
i.e., eggs and 2nd instar larvae. Beginner rearers are supplied with 2nd instar larvae, which experienced rearers can
purchase egg. This is important operation. For this purpose government has established many silk worm seed

ccentres from where the rearers get their seeds at fair price.
(e) Rearing of Caterpillars : The caterpillars are reared at room temperature in shady places at about 60 to
70% humidity. The mulberry leaves supplied to Ist and 2nd instar larvae are well chopped, fresh and kept in wet
clothes so as to keep them fresh. The caterpellars eat voraciously and grow in size and moult. The form of larvae
between two successive moults is known as instars. Larvae have five instars. The last or 5th instar larvae stop feeding
and undergo pupation.

(1) Spinning of Cocoons : Full grown 5th instar larvae secrete a pasty material from its silk gland. It moves
its head to and fro, secreting a silk thread. The spinning larvae are picked up and kept in spinning trays. The trays
are kept in slanting position towards the sun. Within a period of three days spinning is and larvae are transformed
into pupae enclosed in cocoons.

A good quality of cocoon is judged by the quantity of raw silk, filament length, strength and splitting power.
The cocoons are marketed and sold.

(2) Post Cocoon Processing : It included following stages:

• Stifling : The process of killing the cocoons is termed as stifling. Eight to ten day-old cocoons are selected
and dipped in hot water to kill the pupae in the cocoons. If cocoons are not dipped in hot water the silk worm cuts
hole in the cocoon and hence the silk thread is destroyed.

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• Reeling : The silk threads from the killed cocoons are removed and wound round a large wheel and then
transferred to spools. This operation is called as reeling and the silk is called as reeled silk.

• Spinning : Damaged cocoons or the damaged outer layer of silk is separated and spun into threads. This
is known as spun silk.

The raw silk is boiled, stretched, purified and washed again and again to shining lustre. Reeled silk or spun silk
is marketed and sold.

(x) Problems of Sericulture : The sericulture industry is facing a number of problems.
(a) Need for Research : There is a great need to better methods of rearing the silk worms. This is necessary
to improve the yield of raw silk and reduce the cost of production.

(b) In order to improve the quality and yield of raw silk improved varieties of silk worm are developed by
hybridization and breeding. There is a need for the improvement of genetic quality of the silk worm.

For research and training in sericulture the Government has opened Research and Service Station in many
states. A Central Silk Board has been established at Bangalore the ministry of commerce.

(c) Diseases : A number of diseases are caused to silk worm. These diseases result in the low yield and
reduce the quality of silk.

Disease of silkworm
(1) Pebrine : It is the most important disease of silkworms. It is caused by a sporozoan called Nosema
bombycis. The full grown caterpillar is attacked. The infection spreads successive generations through eggs of a
infected moth therefore eggs from healthy moths alone should be taken for rearing worms.

(2) Muscardine : It is a fungal disease caused by Beauveria bassiana and transmitted by spores carried by
winds. All stages of caterpillar are attacked.

(3) Flacherie : It is a bacterial disease caused by Bacillus bombysepticus. Digestion in the affected
caterpillar gets disturbed Regular feeding of the larvae and maintaining hygenic conditions will prevent the disease.

(4) Grasserie : The causative agent of this disease is the nuclear polyheadrosis virus. The affected larvae
become swollen and like a bag of granules, the body fluid becomes thick and cloudy and the larvae die.

(xi) Economic Potentialities of Cultivating Silk in Madhya Pradesh : Madhya Pradesh is the largest
state with respect to land area and has rich subtropical vegetation. Thus Madhya Pradesh holds vast economic

cpotentialities of cultivating silk Sericulture is an important rural cottage industry. The tribal and other rural

population in south east and east M.P. is favourably disposed for the cultivation of silk. Once M.P. was not a
significant state in the list of silk producing states of India but due to the efforts of Madhya Pradesh Government in
the direction of promoting sericulture today it, is the second largest state after Karnataka in the field of production of
row silk.

(xii) Efforts made by Government of M.P. to Promote Sericulture in state : A directorate of silk has
been organised under the Panchayat and Rural Development Department to make concentrated efforts. These
activities have been divided in two categories :

(a) Kosa silk Area : It extends in the eastern and south eastern parts of the state. This area is predominated
by tribal population and is spread in the districts of Balaghat and Mandla.

(b) Mulberry silk Area : It is spread in the western and middle parts of the state including the districts of
Indore, Dhar, Dewas, Khandwa, Ujjain, Shajapur, Raigarh, Mandsaur, Guna and Sehore. For the
promotion of the production of Kosa silk (now Mulberry silk) following efforts are being made.

(1) Kosa Seed Centre : Twelve Kosa seed centres have been established to provide scientific and technical
information to the Kosa silk worm rearers. These centres also provide disinfected improved kosa seeds and
caterpillars to the rearers.

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(2) Kosa Guidance and Training Centre : Madhya Pradesh Government has established 67 centres which
meet the basic needs of supplying disinfected improved seeds of Kosa silk and impart training and guidance to the
rearers.

(3) Nursery : To meet the needs of the host plant and supply of leaves to the rearers the government has
established nurseries of Terminalia tomentosa and Terminalia arjuna. Plantation of host plants has been
undertaken in 296 hectares of land and 1285 hectares of land is proposed to be covered under this scheme.

(4) The construction of two grainage, one cold storage, one cocoon market and one reeling factory is being
undertaken.

(5) Kosa Regional Research centre has been established to help the rearers to increase the yield and improve
the quality of silk.

(c) Mulberry silk Plans : To promote the mulberry silk production in M.P. certain efforts have been made in
the direction by the Madhya Pradesh Government. These are

(1) Establishment of Nursery : To increase the production of host plant Mulberry silk worm, the Morus
indica, nurseries have been established.

(2) Mulberry silk seed centres have been established.

(3) Integrated rural development projects have prepared for the production of Mulberry silk.

(4) Establishment of regional research centre and reeling factory.

(5) Demonstration and publicity plans.

Madhya Pradesh Government has allocated 476.22 lac of rupees for the development plans of silk For the
year 1985-86 a target of 80,000 kg. of Kosa silk and 8356 kg. of Mulberry silk.

Apiculture.
Apiculture is the science of rearing honeybees for obtaining honey, wax and venom. It is a profitable money-

making hobby. It forms a cottage industry, when carried out on a large scale.
Three species of honey bees are commonly found in india vig. Apis indica (The small indian bee). Apis florea

(The little indian bee) and. Apis dorsata (the giant bee) other important species include Apis milifera (the common

cEuropean bee) and apis adamsoni (the African bee) In india the commonly domesticated species are Apis milifera

and Apis Indica.
(i) Honeybee-Apis : Like termites, honeybees are social insects

known for producing honey and beeswax, and for living in very highly
organized colonies. These feed upon nectar and pollen of flowers, possess
“sucking and chewing” mouth parts, and undergo complete metamorphosis.
Each colony has its own nest called honeycomb or beehive. The hive is
thirty to ninety centimetres. It comprises thousands of small, symmetrical and
hexagonal chambers, called “cells”, made up of beeswax. Karl Marx
Commented that the architectural arrangement of “cells” in a beehive puts
the best of human- made architecture to shame. The ''cells'' are used for
storing honey and pollen breads, as well as, for rearing the brood.

Beehives are found upon tree branches, or hanging from ceilings of old
abandoned houses, or inside caves and hollow stems of old trees.

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(ii) Division of labour and polymorphism : Each beehive harbours a colony of thousands of polymorphic
bees belonging to a single family. The polymorphic individuals are of three main types (i) a single queen (fertile
female)(ii) one to a few hundred drones (fertile males) and (iii) thousands (upto 60,000) of worker bees (sterile
females).

(a) The queen : She is the supreme being in a colony, because all the main activities in the hive revolve
around her. She normally lives for about five years, and does nothing except laying eggs. That is why, she possesses
immensely developed ovaries, a large abdomen, and a body which is nearly five times larger and about three times
heavier than that of a worker bee. In other features, she is degenerate, having small wings and poorly developed
legs, mouth parts, sting, brain, etc. She has no salivary or wax glands. Hence she can either produce honey or wax
nor can she fly out of the hive. She therefore, depends for food completely upon worker bees. Although she can use
her sting, but it is mainly used as an ovipositor for laying eggs. She lays about fifteen lac of eggs during her lifetime.
Normally one to three thousand eggs are per day. Egg-laying is a seasonal activity occurring during winters and
spring in our country.

(b) The drones : These are smaller, but stouter than the queen, with broader abdomen, longer appendages,
and larger wings, brain and eyes. These also lack salivary and wax glands, and depend for food upon worker bees.
These even lack a sting and, hence have no defense. Their sole function is to fertilize the queen. Hence, during
breeding season, these are well-fed by the workers, and can be often seen flying near the hive, enjoying or chasing
and mating with young queens in fight. After breeding season, in the following summer, the drones are neglected
and eventually driven out of the hive to die of hunger and heat.

(c) The workers : These are considerably darker and smaller, and most robust with strongest mouth parts
and well- developed wings. Their body is densely covered with hair like bristles. These possess four pairs of pocket-
like wax- secreting glands upon ventral surface of second to fifth abdominal segments. The wax is chewed by
means of mandibles and, then used in constructing new ''cells'' in the colony. The legs of worker bees are modified
to collect pollen. When these bees visit flowers for sucking nectar, numerous pollen grains stick to their bristles and
mouth parts. The legs are equipped with "pollen brushes" of stiff bristles which brush off the pollen from various

cparts of body and collect these in two ''pollen baskets''. The latter are pit like concavities upon dorsal surface of the

wide tibia of hind legs (= metathoracic legs).

Due to their heavy-duty life, the worker bees live only for two to four months. Each worker bee spends its life
in tireless tail. We can say that it has no childhood, because as it becomes an adult bee, it starts working for the
colony from the very first day. Its functions change with age. Accordingly, the worker bees of a hive fall under age-
groups or castes as follows:

(1) Scavenger or Sanitary bees : For the first three days, each worker bee acts as a scavenger, cleaning the
wall and floors of abandoned, empty ''cells'' of the colony for reuse.

(2) House or Nurse bees : From the fourth day onwards, each worker bee feeds the earlier brood, like a
foster mother, with a mixture of honey and pollen. At times, it flies out but only around the hive just to become
familiar with its surroundings. From the seventh day, the maxillary glands of a worker bee begin to function. These
secrete ''royal jelly'' with which the bee now starts feeding young larvae, the queen and those older larvae which
are destined to develop into future queens, From the twelfth to the eighteenth day, each worker bee develops wax
glands and works upon the architecture of the hive. Wax is secreted in the form of thin scales. Middle legs scrap the
scales, bring these in between the mandibles for chewing and mixing with saliva and, then, mould and use these in
constructing new ''cells''. These bees also repair old cells, filling, cementing and varnishing cracks and crevices of
these cells by means of a bee-glue called propolis. Propolis is prepared from resins collected by the bees from.

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(iii) Life History : Queen lays about 2,000 eggs a day. The eggs are laid in the comb, one in each cell. They
hatch out into larvae in three days. They are fed on royal jelly for a few days. But the larva which develops into the

queen will be fed on royal jelly continuously.

During breeding the queen bee flies in the air along with the males. This phenomenon is called nuptial

flight. During nuptial flight the queen copulates with a male Copulation occurs in the air. Then the bees return to

the comb and the queen starts laying eggs.

(iv) Bee-Hive : Honey bee is one of the few domesticated insects. In modern days bee colonies are reared in

artificial wooden boxes for maximum production of honey and wax. The artificial box where the bee colony is

maintained and managed is called hive. The place where hives are kept and managed is called apiary.

There are different models of hive; but the most common model in use is Newton's hive designed by Rev.

Fr. Newton. The hive is in the form of a wooden
cimprints. They are detachable. They are available in the market.
stand. The hive has two chambers. One is the upper

and the second one is the lower. The upper chamber

is called super or honey chamber. The lower

chamber is called brood chamber. The queen is

kept in the brood chamber. The two chambers are

separated by a wire grid called queen excluder.

The holes in the queen excluder are so smaller that

they prevent the entry of the queen into the super,

but allows other bees to pass through. As a result the Life history of Apis indica
eggs are laid only in the brood chamber. The super

chamber is meant for storing honey.

The brood chamber is placed on a bottom board. This board extends forwards as an alighting board on

which the bees rest for some time before entering the hive. The brood chamber has an entrance through which the

bees enter. The super chamber has a ventilator. The super is covered ovary by a roof.

Honey mainly consist of monosaccharides

Both the chambers contain about 7 rectangular wooden frames called comb frames arranged vertically. The

vertical frames are filled with comb foundation sheet. These sheets are made of wax and contain hexagonal

A set of bees with a queen is introduced into a hive. They construct the comb in the vertical frames starting

from the comb foundation sheets. Honey is collected in the combs of super and the eggs, larvae and the young

ones are kept in the combs of brood chamber. When all the cells are filled with honey, the cells are capped or

closed by a thin layer of wax.

(v) Honey extraction : Honey is stored in combs of super frames. It is extracted from the comb by a simple
machine called honey extractor. It has a drum containing a rack inside to hold the super frames. It is made to

rotate by a set of two-gear wheels, operated by a handle.

The super frames are removed from the hive. The caps of the comb cells are cut off by a double edged knife.

Then the frames are fixed in the rack and the rack is made to rotate by operating the handle. The honey is forced

out into the drum from the comb cells. From the drum the honey is collected in vessels through an exit present in

the drum.

(vi) Location of Apiary

• The hives should be set, in places where there are plenty of flowering plants.

• They should be placed in shady places.

• The place should be neat and clean and free from any obnoxious smell.

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• There should be clean drinking water near by because each bee colony requires two glasses of water per
day for their survival

(vii) Protection

• Honey bees should be protected from garden lizard and snakes.

• Black ants steal honey. So water should be placed at the base of the stand.

• Wasps kill honey bees. So protection should be provided against wasps.

• Wax-moth damages the combs. So the combs must be '' protected from wax-moths.
(viii) Formation of honey : Honey is a viscous sugary fluid formed from the nectar within the stomach of
the honey bee. The bees visit flower, suck the nectar, store it in the stomach and return to the hive. In the stomach
the nectar is processed. It is regurgitated and swallowed repeatedly for about 240 times. Then the processed nectar
is deposited in the comb cells. This processed nectar is called unripe honey or green honey. It contains about
80% water. The unripe honey is converted into ripe honey by evaporation. This evaporation is facilitated by two
methods. They are 1. The workers set up an additional circulation of air in the comb by beating their wings and 2.
The worker bees carry nectar several times from one cell to another until the unripe honey becomes viscous. The
ripe honey contains less than 20% water. When the honey becomes ripe, the cells are capped or closed. The honey
in the unsealed cell is unripe.
(ix) Chemical composition : Honey contains nearly 80 different substances of importance to human
beings. The important chemicals are as follows:

• It contains a large amount of glucose or fructose.

• It contains proteins as well as fats.

• The vitamins present in honey are A, B1, B2, B3 , B6, C, E and K.
• A variety of enzymes are present in honey. They include diastase, invertase, saccharase, catalase
peroxidases and lipases.

• It contains many organic acids. The most important organic acid is formic acid; other organic acids are

cmalic acid, citric acid, tartaric acid and oxalic acid.
• It contains a variety of minerals like Ca, Na, K, Mg, Fe,Cl,P,S etc.
(x) Value of Honey – Honey is a valuable food and medicine. Its uses are summarised below:
(a) As it has high content of sugar it is used as a sweetener. Until last century before the discovery of sugar
throughout most of human history honey was the only available sweetener.

(b) Honey has a high calorific value. One kilogram of honey has 3350 calories while 1 litre of milk contains
only 310 calories.

(c) Many athletes drink honey before games and between events in order to restore the energy used up.

(d) Doctors prescribe honey for old people and children who need to build up their strength quickly.
(e) Honey contains biogenic stimulators i.e., substances that heighten the activity of organisms. It has been
proved that cuttings from trees, planted after treatment in a solution of honey, take root easily and grow well.
(f) Honey is used to heal wounds.
(g) It is used to cause free urination.

(h) It is used as a means of easing the belly.

(i) It is a good tonic for ulcer.

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(j) It facilitates digestion and improves appetite.

(k) It prevents a running nose. It is a sure remedy for cold and cough.

(l) Honey is used as medicines for children to treat complaints of the liver.

(m) Honey is good for kidney patients. People suffering from kidney stones are a divised to take a table spoon

of honey, lemon-juice and olive oil.

(xi) Bee wax : Bee wax is secreted by the abdominal gland of bees. It is used for the construction of comb. It
is an yellowish solid insoluble in water. It is used for the preparation of paints, varnishes, candles, models, etc. It is
used as a ground substance for the preparation of ointments, creams etc. It has many industrial uses. It is used
extensively in engineering industries, railways, textiles, leather industries etc.

(xii) Bee venom : Bee venom is secreted by the poison-glands of stings. Bee venom is a curative toxin in
humans. It is transparent and it has a bitter burning taste. It is acidic in nature. It contains formic acid, histamine,
tryptophan, sulphur, many proteins, volatile oils, enzymes like hyaluronidase and phospholipase and magnesium
phosphate. Clinically it has the following uses :

(a) It is an active remedy for rheumatism.
(b) It is used to treat certain eye diseases like keratoconjunctivitis (inflammation of cornea), iris (inflammation
of iris), iridocytis (inflammation of iris and ciliary body).
(c) It is used to cure skin diseases like tuberculosis of the skin.
(d) The cholesterol level in blood falls by the treatment of bee venom.
(e) Bee venom controls blood pressure.
(xiii) Waggle Dance of Honeybees : The exploitation of food sources by honeybees has been studied for
decades, but its study still offers important challenges for zoologists. One of these areas of research concerns the
extent to which honeybees communicate the location of food to other bees.
The communication of honeybees is remarkable because the so-called language of the bees uses a variety of
stimuli to impart information about the environment. Karl von Frisch, famous ethologist, carried out many
detailed bee experiments in the 1940 and was able to determine that when a foraging bee returns to the hive, it
performs a waggle dance.

• Waggle Dance : A worker bee that returns to a hive laden with nectar and pollen stimulates other

cexperienced workers to leave the hive and visit productive pollen and nectar sources. Inexperienced workers are

also recruited to leave the hive and search for nectar and pollen, but stronger stimuli are needed to elicit their
searching behaviour. In the darkness of the hive, the incoming bee performs what researchers have described as
a round dance and a waggle dance. Throughout the dancing, other workers contact the dancing bee with their
antennae and mouth parts, picking up the odours associated with pollen, nectar and other objects in the vicinity of
the incoming bee's food source.

• The dance, which indicates the distance and the direction of a food source, has a figure pattern. As the bee
moves between the 2 loops of the figure it buzzes noisily and shakes its entire body in so-called waggles. Distance
to the food source is believed to the indicated by the number of waggles and or the amount of time taken to
complete the straight run. The straight run also indicates the location of the food. Outside the hive, the dance is
done on a horizontal surface and the straightaway indicates the exact direction of the food. Inside the hive, the
dance is performed on the comb, which is vertical, and the angle of the straightaway to that of the direction of
gravity is the same as the angle of the food source to the sun. In other words, a 40° angle to the lefts of vertical
means that food is 40° to the left of the sun.

As mentioned, honeybees can use the sun as a compass because their biological clock allows them to
compensate for the movement of the sun in the sky. In the dark hive, bees use a combination of the tactile and

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auditory communication. Through touch, bees can determine the direction and waggles of the dance. Not only the
waggles but also the buzzing noises of the dancer tell the distance to the food source.

These observations indicate that bees communicate information regarding distance, direction and kind of food
to other bees when returning from a foraging trip. Thus, the exploitation of pollen and nectar is a very efficient
process and is one source of evidence of the highly evolved nature of the honeybee colony.

Lac Culture.

Lac is the resinous secretion produced by lac insect as protective covering around its body. It belongs to
genera Laccifera or Tachardia Lacifera lacca is the common Indian lac insect. It lives on the trees of fig family
namely kikar, ber (Zizyphus mauritiana), babul (Acacia nilotica), dhak or palas (Butea monisperma), kusum

(schleichera oleosa), Katha or khair (Acacia catechu), peepal (Ficus religiosa) and gular (Ficus glomerata).

Lac insect feeds upon the sap of its host plant like any other sap sucking insect. It is found in India and
Philipine islands.

(i) Male and female chambers : The adult male and female insects live on the tree twigs enclosed in thick
capsules or chambers separately. The male chamber are elongated and cigar- shaped. Each male chamber has a
branchial aperture in its anterior part. There is an opening in the posterior part of the chamber which is covered by
an opereculum. The male insect can crawl out through this opening.

The female chamber is smaller and rounded. It has a branchial aperture in its anterior part and a tubercular or anal opening in
the posterior part. A ridge extends in the mid-dorsal line of female chamber, which indicates the posterior end of the last larval skin.

(ii) Male and female lac insects : The lac insects have a sluggish and almost sedentary life, living inside the
chambers. Therefore , these have become degenerated, without wings and distinct legs. However. the female is
more degenerated. It has a bag -like body with a small reduced antenna. The eyes legs and wings are lost during
metamorphosis. The male lac insect is red in colour. It has an incipient head with antennae and eyes. The thorax
has three pairs of legs and abdomen carries genital sheath, penis and a pair of long caudal setae, one on either side
of genital sheath.

The wings may be present or absent. Because of the absence of mouth parts, the insect is incapable of
feeding.

(iii) Life-cycle : The male lac insect crawls out of its chamber by pushing open the operculum reaches the
female chamber and fertilizes the female through the
anal or tubercular opening of female shell. The male
dies soon after copulation. The female secretes more

cresin forming a large sized chamber. Thus the secretion
by females mainly contributes to lac.

Oviposition takes place into a space inside the
female chamber made by the contraction of the body
of female. This space is called incubating chamber.
Each female lays 200-300 eggs. The eggs hatch into

red coloured larvae. These crawl out of the female's
incubating chamber. The mass emergence of larvae is
called swarming.

Each larva is boat-shaped in appearance and is

about 1/2 mm in length. Its head bears paired (Tachardia lacca)
antennae and the ocelli. The mouth parts are of
piercing and Sucking type with maxillae and

mandibles together forming the sucking tube or
proboscis. Its thorax is three segmented and each thoracic segment carries a pair of walking legs. The abdomen
bears a pair of long caudal setae.

(iv) Attachment of larvae to new shoots : The larvae on emergence craw1 on the twigs of any one of the
host trees mentioned earlier and settle down on the undersurface of new shoots. These prefer young succulent

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shoots. These force their proboscis through the bark and insert it into the phloem tissue and start feeding. Here
these metamorphose into the adult insects and by secreting lac enclose themselves into the chambers.

(v) Secretion of Lac : The secretion forms a shining layer over their bodies in the beginning but hardens and
becomes opaque later on. The secretion is produced by the cutaneous glands of the skin and is deposited around
three openings the two branchial apertures at the anterior end and anal opening at the posterior end. The secretion
is in the form of waxy filaments which have a woolly white appearance. On coming in contact with air, these join to
from a continuous covering. Further, lac secretion continues inside this coating so that lac deposition adds to the
thickness of the coating. With growth of larva and addition of lac the adjacent chambers of different larvae coalesce
with one another forming a more or less continuous encrustation.

(vi) Lac Cultivation : In order to obtain lac, lac insects are cultured and the technique of lac production is
known as the lac culture. It involves proper care and regular pruning of the host plants, propagation of insects, and
collection and processing of lac, For the purpose of propagation the older branches containing crusts are tied with
new branches and this method is called oculation. When new crusts are formed, the old twigs are removed
(approximately 20-30 cm long) and this is known as harvesting.

After inoculation, lac insects come out of the old crusts. At this stage they are known as nymphs. The nymphs
hatch out from eggs laid by the females in the old crusts. The coming out of nymphs from the old crusts is known as
swarming, some of the nymphs become winged or wingless male and others become female. These nymphs explore
new branches. The thousands of nymphs settle side by side, and the resinous secretion builds up around them and
completely encases them. The nymphs undergo several moults. Most of them develop into females and some into
males. The females remain in small cavities in the resinous mass from which they never come out.

(vii) Extraction of Lac : The largest yield of lac and dye are obtained by harvesting the infested twigs while
females are still living. The harvesting is done twice a year in June and November. The encrused twigs are pruned
and lac scrapped from them. This is known as stick lac. It is grounded and sieved. The resulting granular lac is called
seed lac, and the fine particles the dust lack. The seed lac is washed, melted spread out in a thin layer and dried
thus forming the shellac of commerce. The dust lac is used for making toys, shellac is used in the preparation of
varnishes, paints and polishes; in making gramophone records and in filling ornaments like bangles and bracelets. It
is used as insulating material.

Lac insects are highly useful to man. They yield lac, the utility of which discussed above. Besides this, a red
dye is obtained from the body of female acts. The dye is used by women to colour the soles of the their feet, skin.

cLac insects are also used for curing lung and stomach troubles.
(viii) Damages Caused to Lac Crop
(a) Lac crops is reported to be damaged by squirrels, rats, and monkeys.
(b) Certain insects also attack lac insect.
(c) Parasites : Eight species of chalcidoids live as parasites in the body of lac insects. These deposit their
eggs into the body of insects through their anal opening.

(d) Predators : Eublemma amabilis and Holcocerea pulverea are the two lepdoteran predators that damage
about 35% of the lac cells. Their females lay eggs on or near the encrustation. The larvae that hatch out bore
through the lac deposit and feed on lac insects.

(ix) Precautions to be Taken During Lac Culture

(a) Lac intended to be used as brood should be cut at or near the swarming period, never more than one

week before.

(b) Lac to be used as brood must be healthy and resistant to the parasite and predator's attack.

(c) Lac used as brood should be removed after a maximum period of 3 weeks from the date of swarming.

(d) All brood lac after use and the lac cut from the tree should be scrapped from the sticks to destroy larvae
and pupae of predators of parasites.

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(e) Lac should not be stored after cutting. It should be treated as soon as possible.

(f) Fumigation and water immersion immediately after cutting are also helpful in the disinfection of Lac by
insects.

(x) Economic importance of Lac : Lac is used in the preparation of sealing wax (shellac), paints, varnish,
the manufacture of photographic materials, electrical goods. Lac is also used in the preparation of bracelets,
buttons, toys and in filling hollow gold ornaments. Lac is also utilized in confectionery trade and in artificial leather
and pottery. Gramophone industry used to consume 30-40% of the annual production in the preparation of
records.

(xi) Cultivation of Lac in India : India has monopoly in the production of lac. It is about 75% of the
world's total output. Approximately 40 lakh ponds of lac is produced. Bihar M.P. and west Bengal are major lac
producing states in India. Thailand is major competitor of India as it shares 25% of the total exports. India exports
about 1,80,400 kg. of lac The use of lac is being gradually replaced by plastic.

Poultry.

Poultry includes the birds like chicken (hen), ducks, geese and turkey. Poultry farming deals with the rearing
of them for their eggs and meat. Fowls are widely distributed as domesticated animal since time immemorial, but in
the present century, it has become an important small scale industry due to modern need for palatable and nutritive
food which it provides in the form of eggs as well as adult animal. An egg laying poultry bird is called hen and the
poultry birds groomed for obtaining meat are called chicken or broilers. Birds specially chicken grown for meat
only is known as Broiler Poultry is closely related to the problems of nutrition. Poultry and poultry products like eggs
are a rich source of animal protein and a right kind of fat for good health.

India and the neighbouring countries, like Burma, Sri Lanka are the original home of the red jungle fowl
(Gallus gallus). It seems that Aseel or Malay fowl were carried to Europe through the Middle East about 2,000 years
ago and have given rise to the present-day European breeds.

(i) Poultry farming v/s livestock rearing : Poultry birds are easy to raise, can be acclimatised to a wide
range of climatic conditions, have short life span and are prolific breeders and thus poultry farming is advantageous
over livestock rearing. Moreover, poultry farming requires less space and easy to manage and maintain and brings
fast returns. Hens have an average yield of 60 eggs per year, but high yielding varieties can produce more than 240

ceggs in a year.
Poultry contributes about Rs. 7,500 crores to the gross national product (GNP) of India. India ranks fifth in the
world's egg production. Egg is one such food commodity which cannot be adulterated. The average per capita
consumption is about 32 eggs and 600 grams of poultry meat a year. At present poultry is estimated to provide
employment to about seven lakh families.

(ii) Raising of poultry – Fowl house : Fowls can be reared in the hills of India without houses, but in the
plains, well- ventilated and illuminated, dry houses are essential. A house of 1.8 x 1.5 x 1.5 m has sufficient
accommodation for six fowls. An open shed or verandah must be attached to this house as run to the fowls for
exercise. The fowl house may be either of wood or brick and the roof is made up of corrugated iron sheets, thatch or
wood. The floor is littered with chopped straw, paddy husk, dry leaves or groundnut hulls. The fowl house must be rat-
proof, with proper drainage. The house and shed should be cleaned daily. Fowls of different ages are kept in separate
houses. In regions with moderate climate, they are kept in cages (coops).

(a) Feed : The quality and balanced quantity of food material are the back-bones of poultry. The feed given to
poultry birds should contain all the essential nutrients like carbohydrates, fats, proteins, minerals and vitamins. The
feed usually consists of mashed cereals like bajra, wheat, maize, jowar, ragi, rice bran and oil cakes. The fish meal'
prepared from the wastes of fish processing industry and meat meal' prepared from the wastes of meat processing
industry is also used to feed poultry birds. The skimmed milk is highly nutritive for young chicks and should be given

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in clean vessels. The green food as fresh tender grass, garlic, lettuce, onions, etc. are important for poultry and should
be given uncooked.

(b) Breeds of fowls : The whole poultry industry is centred round the fowls so the selection of good breed of
birds for particular area is essential. The selection of fowl breed should be based on the object with which fowls are
kept. Some important indigenous breeds of domestic fowl (desi hens) include Aseel, karaknath, Basara, Chittagong,
Ghagus, Brahma and Cochin. Desi hens are hardy (strong) and possess natural immunity against common diseases,
but they are small, slow growing, and lay small- sized and less number of eggs. The average egg production of a
desi hen is about 60 eggs per annum, which is very poor. Keeping this fact in mind , a large number of poultry birds
have been imported, bred and acclimatised to local conditions. Some of these are excellent egg layers while others
are good meat producing birds. Some of the high egg-yielding exotic breeds of hens which have been successfully
acclimatised in India include white Leghorn, Rhode Island Red, Black Minorca, Plymouth Rock, Light Sussex and
New Hampshire. White Leghorn is one of the most popular egg breeds all over the world. The local varieties of hen
(disi hens) have been cross bred with the high-yielding varieties of exotic breeds to obtain new breeds which
combine the good characteristics of both the breeds. The new improved breeds (hybrid breeds) of poultry birds
grow fast, take less feed, lay more bigger-sized eggs, and are more resistant to diseases. ILS - 82, B - 77 HH - 260
are some important improved, high yielding breeds developed in India by cross breeding. The ILS-82 and B - 77
breeds lay about 200 eggs, whereas HH - 260 breeds lay more than 260 eggs per annum.

(c) Diseases of poultry : The poultry keeper should always be careful against the diseases. Some important
diseases of poultry birds are fowl pox, ranikhet (viral), fowl cholera, salmonellosis, diarrhoea, coryza (bacterial) and
aspergillosis (fungal) However, the most common disease amongst fowls is Ranikhet disease, caused by a virus.
The disease affects the fowls of all ages. In this disease bird opens the beak, becomes thristy, suffers from fever and
yellowish - white diarrhoea occurs. It is followed by nervous symptoms like twisting of the head, circular waling and
paralysis. The birds become very weak and die within two to three days. Mortality is very high about 98 to 100 per
cent. But, with better management, proper housing and nutrition and timely vaccination of the chicks, the disease
can be controlled very effectively.

 Ranikhet diseases is found in Hens

(iii) Other poultry birds : Besides domestic fowl, other birds like ducks, turkeys, etc are also raised. Ducks
comprise about 6 per cent of the total poultry population in India. They are more abundant in the southern and

ceastern parts of India. Muscori, pekin, Aylesbury, Campbell, India Runner and Syhlet meta are some important

breeds ducks. Narfold, British white, Broad Breasted Bronze and Beltsville small white are some important breeds of
turkeys in India.

(iv) Poultry development in India : Poultry is one of the important components of the farmer's economy as
it provides additional income and job opportunities to a large number of rural population in the shortest possible
time. Central poultry breeding farms at Bombay, Bhubaneswar, Hessarghatta and Chandigarh engaged in scientific
poultry breeding programme developed high egg producing hybrids and fast growing broiler breeds. Central Duck
Breeding Farm at Hessarghatta is catering to requirements of high egg producing khaki campbell breeding stock
duckling. The poultry industry has grown rapidly in India in the last twenty years from a backyard farming activity to
a modern and highly scientific industry. As a result of government's efforts, during the seventh plan period, egg and
broiler production registered a compound growth rate of 7.3 per cent and 18 per cent respectively. The egg
production is estimated to be about 26.1 billion in 1994-95.

(a) Broiler or fryer – The chicken use for meat.

(b) Brooding – Living and brood out egg for incubation in particular condition.

(c) Cannibalism – Peeking of fowls among them selves.

(d) Cockerel – Young male fowl.

(e) Rooster – Mature male fowl.

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Fisheries.

Fishes are a valuable and easily accessible source of food, rich in protein, highly nutritious and easily

digestible. By the aquatic animals, they are abundantly available from sea, rivers, lakes, ponds and marshes.

Aquaculture is the production of useful aquatic plants and animals such as fishes, prawns, shrimps, lobsters,

crabs, molluscs by the proper utilization of small and large bodies of water. Pisciculture is the production and

breeding of fishes by man in ponds.

India has abundant marine and inland fish resources. It has a cost line extending to 4667 Km long and a

continental shelf of 2,59,00 square Km offering good scope for fish production. The fish production has increased many

folds since India got independence. During 1990-91 the annual fish production of our country has been 38.22 lakh tons.

The per capita consumption of fish in India is estimated at 1.51 Kg/year. India is at present the 6th foremost seafood
Zoological name

(a) Fresh water fishes

1. Catla catla
2. Labeo rohita
3. Labeo calbasu
4. Cirhinus mrigala
5. Mystus singhala
6. Heteropneustes fossilaris
7. Wallago attu
8. Clarius batrachus
(b) Brackish water fishes

c9. Chanos chanos
producing nations in the world.
(i) History : From pre-historic period, fishes have used as protein rich diet for human beings. The popularity

of fishes has been mentioned in our religious books like Ramayana and Mahabharata also.
In west Bengal, Bihar and orissa, the fish industry is about 1,500 years old. In Bengal every family traditionally has atleast

one pond for fishes.
Classsification of cultivable fish species :

Common Name Areas of availability

Catla All over India common in Krishna and Godavari rivers
Rohu North, East and South India
Calbasu North and South India
Mrigal North and South India
Singhala All over India
Singhi All over India
Malli North, east and South India
Fresh water shark magur All over India

Milk fish A.P.coast

10. Mugil cephalus Grey mullet East coast

11. Laters calcorifer Perch East coast

(c) Marine fishes

12. Sardinella longiceps Oil sardine West and south coasts

13. Harpodon heherius Bombay duck Maharastra coast

14. Hilsa ilisha Hilsa/ Indian shed Coastal India

15. Stromateus sinensis Pomfret Indo pacific coast

16. Anguilla anguilla Eel Coastal India

17. Aluitheronema Salmon East and west coast

18. Cyano-glossus semifas- ciatus Flat fish East coast of India

(ii) Culture method : The success in fish culture and the high production of table - size fish through carp
culture depends largely on the designing and construction of ponds. The basic principles involved in designing and
construction of carp culture ponds are of very specialized nature and vary form region to region depending upon
several factors like topography, soil types, water supply etc. The requirements with regard to the designing and
construction of fish farm are entirely different from those attributed to agriculture and animal husbandry farms.

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(iii) Types of Ponds : Ponds for carp culture may be broadly classified into three types : (a) the nursery
ponds, (b) the rearing ponds and (c) the stocking ponds. The ponds which are small and shallow are used for

raising fry from spawn (4-5 mm to 25-30 mm) may be termed as Nursery ponds or Nurseries. Ponds used for

rearing fry upto fingerling stage (50 mm and above) are known as Rearing ponds. The rearing ponds are slightly

larger but not proportionately deep and are used for rearing fry

upto fingerling (50 mm & above) stage. While ponds which are

used for stocking fry/fingerlings to obtain table-size fish may be

called as stocking ponds. The stocking ponds are still larger and

deeper (0.2 to 2.0 ha in size and 2 m to 2.5 m in depth).

(iv) Species Composition and Species Densities : c(AFishFarm)

Rearing of dietetically compatible species is one of the fundamental
principles in fish culture. The divergent feeding habits of the Indian

major carps and of the exotic Chinese carps are therefore taken
advantage of in mixed culture. This divergence of feeding habits

develop, as stated earlier, from advance fry stage and yet limited

over- lapping in feeding habits is but to be expected. In view of this,

trials were made with two, three. Four and six species

compositions, within which variation in species densities or ratios

were also attempted. Some of the combinations tried were as

follows :

Silver carp + Grass carp :: 1:1

Catla + Rohu + mrigal :: 2:4:4

Silver carp + grass carp+ common carp :: 4:3:3

Catla + Rohu + Mrigal + common carp :: 3:4:1:2
Catla + Rohu + mrigal + Grass carp :: 8:3:1:4

Silver Carp + grass carp + common

Carp + Rohu :: 2.4:1.2:2:2.4

Catla + Rohu + Mrigal + Silver

Carp + Common Carp :: 2.4:4.8:1.0:2.4:2.4

(v) Types of Breeding

(a) Natural Breeding Habits : Major carps are essentially river fishes. They normally do not breed in confined

waters Major carps breed in rivers throughout monsoon month's i.e. June to August. Major carps exhibit local

migration in monsoon months. After travelling some distance against current in flowing waters, they enter shallow

marginal inundated waters, where they breed. These fishes do not exhibit any parental care. Ova are small, numerous

and fertilization is external. Females lay eggs and the males sprinkle its milt over the eggs which are fertilized by inter-

mixing of water, Milt or seminal fluid milky white non-sticky and non-granular. Milt consists of innumerable

microscopic structures called spermatozoa. These spermatozoa have small head. During the period of their existance,

they are extremely active inhabiting a constant jerking motion.

There is sexual dimorphism in major carps. Females are generally larger than males Following factors are

important which influence spawning of major carps.

(1) Right stage maturity of fish (2) Heavy monsoon floods

(3) Extensive shallow spawning grounds (4) Current and flow of water

(5) Optimum temperature (6) High dissolved oxygen

(7) Increased pH (8) Turbidity

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(9) Mineral solution and insuspension. (10) Instinct and physiological effect on fish.

(11) Endocrine secretion

Optimum temperature seem to be essential for breeding but major carp have known to breed over a wide range of

temperature between 40 C - 400 C. Some have suggested that excessive dissolved oxygen is essential but carps have bred

in water where the dissolved oxygen was actually reduced due to mixture of pollutants after the floods. pH from 7.5 to

8.3 are recorded to be suitable for spawning. Turbidity do not seem to be essential for breeding of major carps. Fish

spawning induced by lightening and thunder is also doubtful. Cloudy day, however, seemed favourable for breeding of

carps. Endocrine and sex stimulating hormone of pituitary gland and series of subsequent physiological changes are

important for spawning

(b) Bundh Breeding of Indian Major Carps : Indian major carps i.e. catla catla, Labeo rohita and

Cirhinus mrigala do not naturally breed in confined waters though they attain sexual maturity in these
environments. Their natural breeding takes place in rivers, certain reservoirs and in artificially constructed bundh
type tanks where. Favourable conditions stimulate than for spawning Bundhs breeding contribute a lot to induce
breeding of major carp fish.

The history of establishment of bundhs, as a source of major carp seed production is not clear. This type of bundh
breeding appears to have originated from west bengal State , especially from the districts of Midnapore and Bankura with
the expansion of fish culture industry in India, the bundhs have been established in several other States namely Madhya
pradesh, Bihar, Uttar Pradesh, Andhra Pradesh, Rajasthan, Haryana and Punjab. The bundhs are of two types viz., Wet
bundh and dry bundh.

(1) Dry Bundh : A dry bundh is a shallow depression enclosed by earthen walls, (locally known as bundh)
on three sides and an extensive catchment area on the fourth. Bundhs get flooded during the south-west monsoon,
but remain completely dry for a considerable period during the remaining part of the year.

The topography of the land has a great role to play in the location and distribution of the dry bundhs. In
bankura district of west Bengal, most of the dry bundhs, are fed with water from storage tanks, constructed in the
upland area.

(2) Wet Bundh : The wet bundh is a perennial pond located on the slope of a vast catchment area of undulating
terrain, with proper embankments having an inlet facing towards the upland and an outlet towards the opposite lower
ends. During summer, the deeper portion of the pond retains water containing breeders. The remaining portion is dry

cand is usedforagriculture.
(c) Induced breeding : One of the dependable source of quality seed supply is by inducing major carps to
breed in ponds by the use of pituitary hormone injections. Pituitary extract for inducing fish to breed is used

extensively in many countries. Use of fish pituitary extracts for stimulating spawning of Indian Major carp is met with

considerable success in recent years. The cost of seed production by induced breeding is very low as compared to

the collection made from natural resources.

(vi) Hormone Injection : Major carps do not breed in ponds due to the fact that the environmental factors
which are responsible for spawning in natural habitats are absent in confined waters. Sex stimulating hormones of

the pituitary gland play an important role in the maturation of gonads and spawning in fishes.

The pituitary extract can be kept effectively and utilized successfully in inducing spawing of major carps

through injection.

The method of injection of pituitary extract are following types.

(i) Intramuscular (ii) Intra paritonial (iii) Intracranial

(vii) Economic importance of fishes

(a) Oils : Fish oils are employed in leather industry for chamoising.

Fish body oils are also employed in the manufacture of candles, lubricants, cutting oils etc. Liver oil is a

valuable source of vitamin A and Liver oils are of medicinal use.

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(b) Fish protein : It is used for edible and industrial purposes.
(c) Fish Meal : Waste products of fish are utilized for preparing feed for poultry, pigs and Cattle.
(d) Fish glue : It is a product mainly of tail regions of fishes such as cod, Haddock, pollack, Hake etc.
(e) Ising glasses (It is use for Comb, Purse, Riben and forming of wine.
(f) Shark fins.
(g) Fertilizers
(h) Controller of Diseases.
(i) Scavengers.

Pearl Culture.

Pearl is a concretion formed by molluscs. It consists of nacre or mother of pearl. It is characterised by(d) Pinctada margaritiferaMarine molluscs
iridescence and translucence.
(e) Pinctada anomioides
Pearls is produced by the marine molluscs such as pearl oyster and mussel.
(i) Types of pearls : Pearls are of seven types. They are the following –
(a) Lingha pearl : This is the best quality pearl obtained from marine oysters.
(b) Seed pearls : The small pearls are called seed pearls.
(c) Baroque pearls : These are spherical pearls formed inside the body.
(d) Blister pearls : These are pearls attached to the shell. They are half-spherical in shape.
(e) Oriental pearls : These are true pearls with a great lustre, beauty and a smooth surface.
(f) Natural pearls : These are the pearls obtained from pearl oysters of deep oceans.
(g) Cultured pearls : These are the pearls obtained from cultivated species of pearl oysters.
(ii) Composition of pearl : The pearl is formed of nacre. The nacre is formed of two substances namely a
calcium carbonate which is in the form of argonite or calcite and an albuminoid substance called conchiolin.
(iii) Pearl-producing animals : Pearls are produced by bivalve molluscs. There are marine as well as
fresh water animals.

(a) Pinctada vulgaris

(b) Pinctada fucata

c(c) Pinctada chemnitzi
(f) Pinctada atropurputea

(g) Haliotis

(h) Mytilus

(i) Placuna blacenta

(j) Placuna maxima

(k) Unio margaritifera

(iv) Cultivable species : Pearls are intensively produced by cultivating pearl oysters. The most important
molluscs cultivated for pearls are Pinctada vulgaris.

(v) Biology of pearl oysters : Pearl oysters are sedentary animals. They are attached to rocks. They have two
values. One valve is cemented to the rocks and the other free. They spawn twice in a year. The eggs are hatched into
free swimming larvae. The larvae sink to the bottom of the water and develop into young oysters called spats. They grow
to their maximum size in four or five years.

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(vi) Pearl formation : The pearl oysters produce pearl as an adaptation against outside materials. When a
foreign material such as a sand grain or a parasite happens to enter the body it adheres with the mantle. The mantle
epithelium at once grows over the material in the form of a sac and encloses it. This mantle epithelium starts
secreting concentric layers of nacre around the foreign material. The completed structure is called pearl.

(vii) Culture of pearls : The culture of pearls is a complex but sensitive process. It involves the following
steps.

(a) Collection of oysters.

(b) Preparation of graft tissue.

(c) Preparation of nucleus.

(d) Implantation. cPearl formation

(e) Rearing of oysters and

(f) Harvesting

(a) Collection of oysters : Oysters for pearl culture are
obtained by three methods. They are as follows :

(1) Pearl oysters are collected from the bottom. Of the sea.

(2) Spats (young oysters) are collected by placing cages in spat-
falling areas of the sea.

(3) In the laboratory eggs of pearl oysters are fertilized and young
once are obtained.

(b) Preparation of graft tissue : The piece of tissue which is
inserted into the oyster is called graft tissue It is cut off from the
mantle of another oyster. The graft must be in the form of a square of 2
× 2 mm in size.

(c) Preparation of nucleus : The nucleus is a foreign material
which is inserted into the oyster. It is in the form of a of 2 mm in
diameter. It is prepared from the shell of molluscs

(d) Implantation : The oyster is placed on a table. The foot is

exposed. A small incision is made on the foot. On this incision the graft tissue is placed. The nucleus is placed on

the tissue. Then the oyster is released in cages. The entire operation should be completed in 30 minutes.

(e) Rearing of oysters : The operated oyster are placed in cages and the cages are suspended from rafts in

the sea. This type of culturing oysters is called raft culture.

(f) Harvesting : Pearls attain their maximum in three years. After three years, the oysters are removed from
cages and the pearl is taken out. Chemically pearl is made up of CaCO3 and conchiolin.

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Microbes in Human Welfare (Microbiology)

Introduction.

Microbiology is the branch of science, which deals with the study of microorganism and their process is called
as microbiology. Antony Von Leeuwenhoek is known as father of microbiology and father of modern microbiology
is Robert Koch. Microbiology is the study of living organism of microscopic, which include bacteria, fungi, algae,
protista, viruses, etc. It is concern with their forms, structure, reproduction, physiology, metabolism and
classification. It includes the study of their distribution in nature and relationship to other living organism. Their
effects on human beings and on other animals and plants. Their abilities to makes physical and chemical change in
our environment.

Bacteria.

Study of bacteria is called bacteriology. Linnaeous placed them under genus vermes. Nageli classified bacteria
under schizomycetes. Bacteria are unicellular, microscopic organisms. These are the smallest cellwall having
prokaryotic cell. They differ from animals in having a rigid cell wall and being capable to synthesize vitamins.
Bacteria were first seen by a Dutch lens maker, Antony Von Leeuwenhoek (1683) who named them animalcules.
Louis Pasteur (1822-95) made a detailed study of bacteria and proposed germ theory of disease. Ehrenberg (1829)
was the first to use the term bacterium. Robert Koch (1881) found that some diseases like tuberculosis, cholera in
man, and anthrax in cattle is caused by bacteria. Lister introduced antiseptic surgery he used carbolic acid for
sterilization of surgical instrument. Pasturization theory was proposed by Louis Pasteur.

(1) Occurrence and Distribution : The bacteria constitute a highly specialised group of one celled plants.
They are cosmopoliton. They flourish in our mouth and intestine. They live in the bodies of other organisms and
their dead remains. Bacteria are not found in healthy blood, depth of some feets in the soil fire and healthy cell.
Some thermophilic bacteria can tolerate the temperature upto 78oC while in psychrophilic bacteria occurs upto the
temperature of – 190oC. The features which contribute to their universal distribution are –

(i) Extremely simple structure.

(ii) Small size and consequent large surface–to–volume ratio. In order to maintain their small size, cell division

coccurs rapidly.
(iii) Resistance of vegetative cells to adverse environmental factors. Such as U.V. light desication. etc.

(iv) Formation of highly resistant endospores.

(v) Diversity in their modes of nutrition.

(2) Plant characteristics : The bacteria are microorganisms that possess rigid cell wall and when motile have
flagella. They are unicellular organisms lacking true nucleus and membrane bounded cell organelles. The plant
characteristics of bacteria are –

(i) Presence of a definite and rigid cell wall which in a few species contains cellulose.

(ii) The tendency of some to grow as filaments.

(iii) The ability of autotrophic bacteria to synthesize organic food from inorganic materials such as CO2 and
water.

(iv) Structure of the bacterium cell and reproductive methods are similar to that of certain algae.

(v) Ability to synthesize amino acids from inorganic nitrogen.

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(3) Size : Bacteria are the smallest of all known cellular organisms which are visible only with the aid of
microscope. They are 3 to 5 microns (1 µ = 1/1000 millimetre or about 1/25,000 inch) in length. A few species of
bacteria are approximately 15µ in diameter.

(4) Shape : The shape bacteria usually

remain constant. However, some of them are

able to change their shape and size with

changes in environmental conditions. Such Tetracoccus Staphylococcus Sarcina
bacteria, which change their shape, are called
pleomorphic. The bacteria possess the Micrococcus Diplococcus Streptococcus

Coccus bacteria

following forms.
(iii) Vibrios : These are small and ‘comma like, kidney like. They have a flagellum at one end and are motile,
(i) Cocci : (GK. Kokkos = Berry) They Bacillus Diplobacillus Palisade Bacillus Streptobacillus
cvibrio bacteria has curve in its cell e.g., Vibrio cholerae.are oval or spherical in shape. They areSpirillumBacillus bacteria
called micrococcus when occur singly as in
Micrococcus, diplococcus when found in Vibrio Mycelial
pairs as in Diplococcus pneumoniae,
tetracoccus in fours, streptococcus when Stalked Budded
found in chains as in Streptococcus lactis,
staphylococcus when occurring in grape like Fig Different forms of bacteria
clusters as in Staphylococcus aureus and
sarcine, when found in cubical packets of 8
or 64 as in Sarcina.

(ii) Bacilli : They are rod–shaped bacteria with or without flagella. They may occur singly (bacillus), in pairs
(diplobacillus) or in chain (streptobacillus).

(iv) Spirillum (Spira = Coil) : The spirillum bacteria (plural-spirilla). They are spiral or coiled like a cork-

screw. The spirillar forms are usually rigid and bear two or more flagella at one or both the ends e.g. spirillum,

spirochaete, etc.

(v) Filament : The body of bacterium is filamentous like a fungal mycelia. The filaments are very small e.g.
Beggiota, Thiothrix etc.

(vi) Stalked : The body of bacterium posses a stalk e.g. Caulobacter.

(vii) Budded : The body of bacterium is
swollen at places e.g. Retrodomicrobiom.

(5) Flagellation : Depending upon the A BC D E
presence or absence of flagella, the bacteria are of
following types :– Fig : Different types of bacteria on the basis of flagellation : (A) Atrichous
(B) Monotrichous (C) Lophotrichous (D) Amphitrichous (E) Peritrichous
(i) Atrichous : When the flagellum is
absent it is called atrichous. e.g. Pasturella,

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Lactobacillus

(ii) Monotrichous : Only one flagellum is found at one end. e.g. Vibrio, Cholerae.

(iii) Lophotrichous : When a group of flagella is present at one end e.g. Vibrio.

(iv) Amphitrichous : When single or group of flagella is present at both the end e.g. Nitrosomonas.

(v) Peritrichous : A number of flagella are present all over the body. e.g. E. coli.

(6) Staining of bacteria

(i) Simple staining : The coloration of bacteria by applying a single solution of stain to a fixed smear is

termed simple staining. The fixed smear is flooded with a dye solution for a specified period of time, after which this

The most plausible explanations for this phenomenon
are associated with the structure and composition of the cell
wall. Differences in the thickness of cell walls between these
two groups may be important the cell walls of Gram-negative
bacteria are generally thinner than those of Gram- positive

cbacteria. Gram-negative bacteria contain a higher percentage
solution is washed off with water and the slide blotted dry. The cells usually stain uniformly. However, with some
organisms, particularly when methylene blue is used, some granules in the interior of the cell may appear more
deeply stained than the rest of the cell, indicating a different type of chemical substance.

(ii) Gram staining : This technique was introduced by Hans Christian Gram in 1884. It is a specific

technique which is used to classify bacteria into two groups Gram +ve and Gram –ve. The bacteria are stained with

weakly alkaline solution of crystal violet. The stained slide of bacteria is then treated with 0.5 percent iodine

solution. This is followed by washing with water or acetone or 95% ethyl alcohol. The bacteria which retain the

purple stain are called as Gram +ve. Those which become decolourised are called as Gram –ve. In general the wall

of Gram +ve bacteria have simpler nature as compared to Plasma Membrane
Gram –ve bacteria. E.coli is a Gram –ve bacterium. Gram

negative bacterium can be seen with other stain safranin. Periplasm

Gram-Negative MMeseossoosmome e

Peptidoglycan

Lipopolysaccharide
Membrane
Teichoic acid + lipoteichoic acid
Gram-Positive

of lipid (11 to 22%) than do Gram-positive (1 to 4%), Fig : Difference between cell walls of
Gram-negative and Gram- positive bacteria

bacteria, Experimental evidence suggests that during staining

of Gram-negative bacteria. The alcohol treatment extracts the lipid, which results in increased porosity or

permeability of the cell wall. Thus crystal violet- iodine (CV-I) complex can be extracted and the color of the

safranin counterstain. The cell walls of Gram-positive bacteria, because of their different composition, lower lipid

content, become dehydrate during treatment with alcohol. The pore size decreases, then permeability is reduced,

and the CV-I complex cannot be extracted. Therefore these cells remain purple-violet.

S.No. Gram - Positive Gram - Negative
Cell wall thin (100 – 150 Å)
(1) Cell wall thick (250 – 300 Å). Cell wall heterogenous.
Cell wall 3-layered.
(2) Cell wall homogenous. Cell wall less rigid

(3) Cell wall single layered.

(4) Cell wall more rigid.

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(5) Cell wall made up of mucopeptide (80%). Cell wall made up of lipoprotein, lipopolysaccharide and mucopeptide.

(6) Teichoic acid (5 – 10%) present. Teichoic acid absent.

(7) Spore producing forms included. No spore producing form.

(8) Polar flagellum usually absent. Polar flagellum usually present.

(9) Contain Mg-ribonucleate. Mg-ribonucleate absent.

(10) Not soluble in 1% KOH. Soluble in 1% KOH.

(11) May produce exotoxins. May produce endotoxins.

(12) Sensitive to penicillin. Not sensitive to penicillin.

(13) L-lysin present in peptide Diamino palmilic acid present in peptide.
(14) O-antigen absent. O-antigen present.
(7) Structure of bacterial cell

(i) Capsule : In a large number of bacteria, a slimy capsule is present outside the cell wall. It is composed of
polysaccharides and the nitrogenous substances (amino acids) are also present in addition. This slime layer
becomes thick, called capsule. The bacteria, which form a capsule, are called capsulated or virulent bacteria. The
capsule is usually found in parasitic forms e.g. Bacillus anthracis, Diplococcus pneumoniae, Mycobacterium
tuberculosis.

Function of capsule

(a) It provides protection against phagocytosis and antibiotics.

(b) Capsule also protects the cell against dessication and viral attack.

Type of capsule

(a) Homopolysaccharide : When capsule are made by one type sugar e.g. Streptococcus mutans.

c(b) Heteropolysaccharide : When capsule are made by many type sugar e.g. Streptococcus pneumonae.
(ii) Cell wall : All bacterial cells are covered by a strong, rigid cell wall. Therefore, they are classified under
plants. Inner to the capsule cell wall is present. It is made up of polysaccharides, proteins and lipids.

(a) In the cell wall of bacteria there are two important sugar derivatives are found i.e. NAG and NAM (N-acetyl

glucosamine and N-acetyl muramic acid) and besides α- Cell wall Plasma Respiratory
or D - alanine, glutamic acid and diaminopimelic acid Capsule membrane chain Cytoplasm
are also found.
Fimbriae Storage
Granule

tRNA

(b) One of the unique components of cell wall of Flagellum
bacteria is peptidoglycan or mucopeptide or murien
(made of mucopolysaccharide + poly peptide). Polysome

(c) In peptidoglycan, NAG and NAM are joined by mRNA Internal Free enzyme
short peptide chains or cross bridges of amino acids. Mesosome Nucleoid DNA membrane
Free
(d) Outer layer of cell wall of Gram –ve bacteria is ribosome

Fig : Electron microscope structure of a bacterium cell

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Microbes in Human Welfare (Microbiology)

made up of lipopolysaccharides and cell wall of Gram +ve bacteria of teichoic acid.

(e) The cell wall of Gram positive bacteria is much thicker and contains less lipids as compared to that of Gram +ve
bacteria.

(iii) Plasma Membrane : Each bacterial cell has plasma membrane situated just internal to the cell wall. It is
a thin, elastic and differentially or selectively permeable membrane that allows passage of dissolved substances in
and out of the cell. It is composed of large amounts of phospholipids, proteins and some amounts of
polysaccharides but lacks sterols. The plasma membrane of bacteria provides site for most of the anabolic and
catabolic pathways. It is characterised by possessing respiratory enzymes, which are bound to its inner surface some
exoenzymes are also associated with its outer surface which catalyze digestion of insoluble materials.

(a) Mesosome : On the plasma membrane generally at mid point, there are present some circular coiled
bodies called mesosomes. If plasma membrane is stretched then mesosomes are disappeared. So mesosomes are
simply infoldings of plasma membrane. Mesosomes contain respiratory enzymes like oxidases and dehydrogenases
and hence they help in respiration. Hence mesosomes are also known as "mitochondria of bacterial cell" or
chondrioides. Mesosomes are more prominent in Gram +ve bacteria.

• Mesosomes are present at mid point, so they help in equal distribution of nuclear material during binary fission.

• It help in secretion and synthesis of material for cell wall.

• It receive DNA during conjugation and DNA replication enzyme.

• Mesosome participate in the formation of septa during cell division.

(iv) Cytoplasm and cytoplasmic inclusions : The cytoplasm is a complex aqueous fluid or semifluid
ground substance (matrix) consisting of carbohydrates, soluble proteins, enzymes, co-enzymes, vitamins, lipids,
mineral salts and nucleic acids. The organic matter is in the colloidal state.

The cytoplasm is granular due to presence of a large number of ribosomes (about 20,000 to 30,000), which

coccur singly or in small groups called polyribosomes. The ribosomes in polyribosomes are held together by means

of messenger RNA. The ribosomes of bacteria are smaller (70S) as compared to those of eukaryotic cells.
Ribosomes in bacteria are found in the form of polyribosome. Membranous organelles such as mitochondria,
endoplasmic reticulum; Golgi bodies, lysosomes and vacuoles are absent. In some photosynthetic bacteria the
plasma membrane gives rise to large vesicular thylakoids which are rich in bacteriochlorophylls and proteins.

(a) Volutin granules : These are so called because they were first reported in Spirillum volutans bacteria.
These are also known as metachromatic granules, which are composed of polyphosphate. They stain an reddish
purple colour with dilute methylene blue. By electron microscopy they appear as round dark areas. Volutin serves
as a reserve source of phosphate.

(b) Fatty acids granules or poly-β-hydroxy butyric acid granules (PHB) : These are polymer of lipid
like material and chloroform soluble which are often found in aerobic bacteria especially under high carbon low
nitrogen culture conditions. Granules can serve as a reserve carbon and energy source. PHB granules can be
stained with lipid soluble dyes such as nile blue. By electron microscopy they appear as clear round areas.

(c) Glycogen and sulphur granules : Glycogen are also known as polysaccharide granules. It can be
stained brown with Iodine. By electron microscopy they appear as dark granules. Another type of inclusion is

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represented by the intracellular globules of elemental sulfur that may accumulate in certain bacteria growing
environments rich in hydrogen sulfide.

(v) Nucleoid : It is also known as genophore, nacked nucleus, incipient nucleus. In contrast to eukaryotic
cells, bacterial cells contain neither a distinct membrane enclosed nucleus nor a mitotic apparatus, However, they
contain an area near the center of the cell that is regarded as a nuclear structure. There is present nuclear material
DNA. DNA in bacteria is double helical and circular. It is surrounded by some typical protein (polyamine) but not
histone proteins. Histones (basic proteins) are altogether absent in bacteria. This incipient nucleus or primitive
nucleus is named as nucleoid or genophore.

(vi) Plasmid : In addition to the normal DNA chromosomes many bacteria (e.g. E.coli) have extraentirely of flagellin protein.
chromosomal genetic elements or DNA. These elements are called plasmids. Plasmids are small circular double
stranded DNA molecules. The plasmid DNA replicates independently maintains independent identity and may carryFilament
some important genes. Plasmid terms was given by Lederberg (1952). Some plasmids are integrating into the
bacterial DNA chromosome called episomes. Plasmids are following type.

(a) F-factor or fertility factor or F-plasmid : Which is responsible for transfer of genetic material from
donar to recepient bacteria.

(b) R-factor or resistance factor or R-plasmid : It provides resistance against drugs. Some of the R-
plasmid can be transferred to other cells by conjugation, hence the term infectious resistance. Each form of
resistance is due to a gene whose product is an enzyme that destroys a specific antibiotic.

(c) Colicinogenic factor : Which produces 'colicines' which kill other bacteria (other than which produce
these colicines).

(8) Flagella : These are fine, thread-like, protoplasmic appendages which extend through the cell wall and the
slime layer of the flagellated bacterial cells. These help in bacteria to swim about in the liquid medium.
Myxobacteria donot has flagella and move by gliding movement. Bacterial flagella are the most primitive of all
motile organs. Each is composed of a single thin fibril as against the 9+2 fibrillar structure of eukaryotic cells. It

cconsists of a few fine fibrils twisted tightly together into a rope-like helical structure. The flagellum is composed
According to Low and Hanson (1965), bacterial flagellum is

composed of globular subunits arranged in helices of various kinds.

The diameter of each subunit is about 40-50Å. These subunits Hook
are arranged around a hollow axis. A flagellum is usually 4.5 µ long
and 120-185 Å in diameter. Flagellum is attached to cell membrane L ring PeOptuidteorgmlyecamnbrane
by a special terminal hook, which is attached to the basal body called loyer
(bleferoplast). A bacterial flagellum can be divided into three parts.
Peptidoglycan layer
(i) Basal granule : It is like a rod it lies with in the cell wall and
cell membrane and bears ring like swellings in these regions. M ring Cytoplasmic

(ii) A hook : It represent the middle and thickest part of membrane

Fig : Structure of flagella

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flagellum. Hook is curved tubular structure which connects the filament with the basal body.

(iii) Filament : It represents cylindrical hollow structure made up of protein monomers.

(9) Pili or Fimbriae : Besides flagella, some tiny or small hair-like outgrowths are present on bacterial cell
surface. These are called pili and are made up of pillin protein. They measure about 0.5–2µm in length and 3–5µm
in diameter. Pilin are arranged helically around a central hollow core. These are present in almost all Gram-ve
bacteria and few Gram +ve bacteria. These are of 8 types I, II, III, IV, V, VI ,VII, and F types. I to F are called sex
pili.

Functions
viable population (death or decline phase). Between each of these
phases there is a transitional period (Curved portion). This

crepresents the time required before all cells enter the new phase.
(i) The function of pili is not in motility but they help in the attachment of the bacterial cells.

(ii) Some sex pili acts as conjugation canals through which DNA of one cell passes into the other cell.

(10) Normal Growth cycle or Growth curve of bacteria : When we inoculate a fresh medium with a given

number of cells, determine the bacterial population intermittently

during an incubation period of 24h (more or less), and plot the Log of numbers of viable bacteria

logarithms of the number of cells versus time, we obtain a curve

of the type illustrated figure from this it can be seen that there is

an initial period of what appears to be no growth (the lag phase),

Followed by rapid growth (the exponential or logarithmic phase), C

then a leveling off (stationary phase), and finally a decline in the B D

A

Time,h
Fig : Growth curve of bacteria

(11) Reproduction in bacteria : Methods of Cell wall Cell membrane
reproduction are following.
DNA A Cytoplasm
Vegetative reproduction Parent cell

(i) Budding : It is a rare method of reproduction E B
and is reported in Bigidi bacterium bifidus. New formed two parts separate Bacterial cell expands
apart from each other and give
(ii) Binary fission : It is the most common type
of reproduction in bacteria during favourable rise to two new cells
conditions. When the conditions of food, water and
temperature are favourable. Here bacterial cell divides New formed two D C Due to the formation of a
by a constriction into two halves. At the same time parts start to transverse septum, cytoplasm
nuclear material elongates and divides into 2 equal divides into two parts
separate apart

Fig : Different stages in the binary fission of
a rod shaped bacteria

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halves probably helped by mesosomes. During this process, the single circular chromosomes duplicates it self a long
with DNA duplication under favourable conditions of binary fission. Bacterial cell divides into two after every 20
minutes and at this rate in 24 hours period, a single bacterial cell produces 4×1021 bacteria, but only about 10% of
them survive, The speed of binnary fission is decreased due to low temperature. Therefore, food is preserved in the
cold storage. The cause of food spoilage and bacterial infection is the rapid multiplication of bacteria.

Asexual reproduction

(i) By endospore formation : During unfavourable condition, highly resistant single spore is formed inside

the bacterial cell, which is known as endospore. (Endo

means inside or within + spore) Endospore means spore Exosporium

c(e) The bacterial spore or endospore is perhaps the most resistant living structure known to science.inside bacterial cell or cell inside cell.Spore coatEndospore

(a) Endospore formation is more common in rod- Bacterial Bacterial plasma Cortax
shaped bacterial or bacillus forms. Position of single cell wall membrane
endospore may be terminal or sub-terminal or intercalary. Cell wall or
core wall
(b) Endospore is having a characteristic structure, i.e.,
having outer thin exosporium followed by one or many Plasma
layered spore coat, followed by cell many concentric layers membrane
of cortex, which if followed by cell wall, cell membrane and
matrix. Spore
cytoplasm

Bacterial
cytoplasm

Fig : Detailed structure of endospore

(c) Endospore is highly resistant to very high and very low temperature, strong chemicals and acids, etc., due
to calcium dipicolinic acid and peptidoglycan in cortex. Dipicolinic acid (DPA) helps in stabilizing its proteins. DPA
and Ca ions provide resistance to heat.

(d) When favourable conditions come, outer layers rupture and active bacterial cell comes out. So this is a
method of perennation (i.e., to tide over unfavourable condition) and some people say it “ reproduction wihtout
multiplication”.

(f) Tetanus causing and anthrax causing bacteria produce endospores.

(ii) By conidia : These are found in filamentous bacteria like streptomyces. The conidia are spore like
structure formed in chains. Each conidium gives rise to a new bacterium.

(iii) By zoospores : Motile spores are formed in Rhizobium bacteria, but are rare in other bacteria

Sexual reproduction (Genetic recombination or parasexuality)

Sexual reproduction in bacteria is not of the kind as found in eukaryotic organisms. In case of bacteria, the sex
organs are not formed, meiosis and mitosis does not occur, the two gametes do not fuse with each other and the
diploid zygote (having two set of chromosomes within a true nucleus) is not formed. Instead, a portion of genetic
material (DNA) is transferred from a ‘donor’ cell (male) to a ‘recipient’ cell (female) making it an; incompletely
diploid zygote. The process is actually called genetic ‘recombination’ which occurs in three ways.

(i) Transformation : In this process one kind of bacterium is transformed into another kind. It takes place by
transferring DNA from one bacterium to another bacterium. It was first reported by Griffiths (1928). Avery, Mcleod
and Mc Carthy (1944) perform a detailed study of transformation in Diplococcus pneumoni. In this experiment one

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type bacteria are virulent (pathogenic) having an extracovering of polysaccharids. These are called capsulated
bacteria or (rough bacteria) or R-bacteria. Another type are avirulent non-pathogenic are called non-capsulated
bacteria or (smooth bacteria) or S bacteria. This experiment was completed in 4 steps.

(a) Avirulent strain Inject inmice→ Healthy mice.

(b) Virulent strain Inject inmice→ Mice die.

(c) (Heat killed virulent strain) Bacterial strain Inject inmice→ Healthy mice.

(d) Avirulent +(Heat killed virulent bacterial strain) Inject inmice→ Mice die

In his experiments, Griffith mixed R-types with the heat killed S-type cells and injected them into a laboratory

that small amount of DNA (i.e., less than 5% of the total genome) is

cactually transferred during transformation. Some of the important
mice. He observed that non- capsulated R-type cells became converted into capsulated types. This shows that a

small portions of DNA from heat killed S-type cells have entered into non- capsulated R-type cells and transformed

them into capsulated types. Capsulated Non Capsulated

DNA

Heat killing

Capsulated

Fig : Transformation of a non capsulated
pneumococcus bacterium into a capsulated type

Transformation are not common in nature because the large fragments of DNA molecules can not pass

through the recipient’s cell walls or membranes, However, this process has been made possible experimentally by

protoplast fusion and other related techniques. It has been shown Phage DNA

A Bacterial
cell 1

characters transferred from one bacterial cell to another bacterial cell Bacterial DNA
by transformations are development of pathogenicity, drug

resistance, formation of capsules and change in the nutritional B

patterns. Bacterial DNA
(ii) Transduction : Transduction is the process in which the

genetic material (a portion of DNA) of one bacterium is transferred to C Phage DNA
another through the agency of temperate (lysogenic) bacteriophage Bacterial DNA
(i.e., bacterial virus). The process was discovered by Zinder and

Lederberg (1952) in bacteria-Salmonella typhimurium. D Bacterial cell 2

During this process a donor bacterial cell gets infected with a Transducted
bacterial virus. The viral DNA, instead of multiplying itself, becomes DNA
associated and integrated with bacterial DNA. Thus the genes of
bacterium get linked with the genes of virus. It is followed by the E
multiplication of virus inside the bacterial cell.
Fig : Transduction where fragment of one bacterial
cell is passed on to another bacterial cell through

the agency of a phage

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Bacterial cell resulting in the formation of normal (containing viral DNA) and defective (containing broken
fragments of the host DNA) bacteriophage. The defective viruses containing the fragments of bacterial DNA are
liberated along with the normal viruses after the lysis of bacterial cell. These viruses attacks the other bacterial cells
infection of a recipient cell by a normal bacteriophage usually leads to lysis. A few recipient bacterial cells, however,
become infected with a defective transducing bacteriophages. Thus the viral DNA, which consists of bacterial DNA,
gets associated and integrated with the recipient bacterial cell completing the process of transduction. In this way,
the DNA fragment of one bacterial cell is transferred to another bacterial cell.

Transduction has been observed in many bacterial genera such as Salmonella, Escherichia, Shigella, Bacillus,
pseudomonas, etc. Two kinds of transduction can be distinguished.

(a) Generalised (non-specific) transduction which can transfer any phage sized fragment of host DNA.
cand F- strains always yields F+ progeny. (F+ + F- → F+).
(b) Specific transduction which is restricted to the transfer of specific portion of DNA.

(iii) Conjugation : Transfer of DNA by the process of conjugation was first described by two American
scientists Lederberg and Tatum (1946) in Escherichia coli. It occurs between two sexually different strains of the
bacteria (E.coli)- one acts as donor of genes (male) and the other as recipient of genes (female) both are haploid.
The donor (or male) cells prossess sex-factor or fertility factor (F-factor). F-factor is a small genetic particle of circular
DNA. It replicates at the time of cell division and inherited by the progeny. The F-factor codes for the special type of
protein that determines the formation of sex pili in donor cells and formation of conjugation bridge or conjugation
tube between the donor and recipient cells. The F-factor may remain free in the cytoplasm (i.e., independent of
bacterial chromosome) or it may be integrated with the bacterial chromosome. If it remains free in the cytoplasm,
the bacterial cell is called F+ strain donor (Male) and if it is attached to bacterial chromosome, the cell is called Hfr
(High frequency of recombination) strain donor (Super male).

During the conjugation between F+-- (male) and F- (female) strains, the two bacterial cells come close to each
other in pair. The F+ cell sends sex pilus which gets attached to F- cell forming a conjugation bridge between them.
The F-factor then divide into two, out of which one remains in the donor cell and the other migrates into recipient
cell through the conjugation bridge. As a result, the F- cell now becomes F+ cell. Thus, a conjugation between F+

F+ (male) × F–(female)

During the conjugation between Hfr (donor) and F–(recipient), Bacterial genome F(fertility) Factor
the two come close to each other forming a pair. The sex pilus
develops from Hfr and gets attached to the wall of F– cell. The Replication of F factor Conjugation tube
common wall dissolves and a conjugation bridge is established. The
chromosome of Hfr breaks at one point and both the strands of broken Migration of replica F+
end begin to replicate. The chromosome of Hfr becomes linear and Factor into female cell
have a directional orientation so that the daughter DNA moves into F–
cell through the conjugation bridge. The migration of DNA into F– is F+(male) F+(male)
such that the F-factor is last to enter. Sometimes complete transfer of
DNA from Hfr to F– is interrupted due to repture at some point, called Fig : Conjugation between F+ male and F– female
R-point. Since complete transfer of DNA occurs only rarely, the F-
factor does not usually enter the F– and the resulting zygote is not
converted to F+. Thus, the newly formed zygote receives only those
genes from Hfr which have been transferred during conjugation.

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Sex-duction : As stated earlier the F-factor (fertility factor or sex-factor) remains free in the cytoplasm of F+
strain donor cell and remains attached to bacterial chromosome in Hfr strain donor cell. Sometimes the F-factor gets
detached from the bacterial chromosome of Hfr strain cell and resumes an independent status inside the cytoplasm.
During faulty separation from the chromosome of Hfr, the F-factor sometimes carries away a small portion of
chromosomal DNA along with it. Such F-factor with extra DNA, when transferred from donor to recipient cell
during conjugation, becomes part and parcel of recipient chromosome making it heterozygous (or partial diploid).
This process is called Sex-duction.

Such F-factor with extra DNA, when transferred from donor to recipient chromosome making it heterozygous
(or partial diploid). This process is called conjugation. The bacterium which shows genetic recombination after
conjugation is called “Merozygote”.

(12) Respiration in bacteria : With respect to oxygen requirement and mode of cellular respiration, bacteria
distinctly belong to two broad categories- (i) aerobic and (ii) anaerobic. These are further divided into obligate and
facultative types. thus, the bacteria can be grouped into four general categories on the basis of their oxygen
requirement.

(i) Aerobic respiration

(a) Obligate aerobes : These bacteria grow exclusively in presence of molecular oxygen and fail to survive
in its absence, e.g., Bacillus subtilis, Azotobactor, Arthrobactor, Mycobacterium, etc.

(b) Facultative anaerobes : The aerobic bacteria which can also survive in absence of oxygen, e.g.,
Aerobacter, Klebsiella, Pseudomonas, etc.

(ii) Anaerobic respiration

(a) Obligate anaerobes : These bacteria grow and multiply in the absence of free oxygen. They fail to
survive under aerobic conditions, e.g., Clostridium botulinum.

(b) Facultative aerobes : The anaerobic bacteria which can also survive in presence of oxygen, e.g.,
Chlorobium limicola.

c(13) Mode of nutrition in bacteria : On the basis of mode of nutrition, bacteria are grouped into two broad

categories. First is autotrophic and second is heterotrophic bacteria.

Autotrophic bacteria : These bacteria are able to synthesis their own food from inorganic substances, as
green plants do. Their carbon is derived from carbon dioxide. The hydrogen needed to reduce carbon to organic
form comes from sources such as atmospheric H2, H2S or NH3. These are divided into two categories.

(i) Photoautotrophic bacteria : These bacteria are mostly anaerobic bacteria. They use sunlight as source
of energy to synthesize food. But unlike other type of photosynthesis as found in eukaryotic cells, they do not "split
water'' to transfer energy or to obtain reducing power. Instead they split hydrogen sulphide, thiosulphate, hydrogen
or some other organic compound and oxygen is not evolved as a byproduct. They possess a pigment called
bacteriochlorophyll which is different from the chlorophyll pigment found in higher plants. This is known as
anoxygenic photosynthesis. e.g. Green sulphur (thiothrix) and purple sulphur (chromatiun) bacteria. They can
perform photosynthesis in far-red light. Rhodospirillum bacteria fixes CO2 into carbohydrate (Photoautotrophic).

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The green sulphur bacteria such as Chlorobium sp. and Chloropseudomonas sp., contain the pigment
bacterioviridin (similar to chlorophyll) and thrive well in illuminated environments. These bacteria produce chemical
sulphur by removing hydrogen from hydrogen sulphide.

6CO2 + 12H2S Light → C6 H12O6 + 12S + 6H 2O + Energy

The purple sulphur bacteria such as Thiospirillum sp. and Chromatium sp., contain the pigments
bacteriochlorophyll and carotenoids. Theses bacteria utilize inorganic sulphur compounds, selenium compounds or
molecular hydrogen.

6CO2 + 15H 2O + 3 Na 2 S2 O3 Light → C6 H12 O6 + 6H2O + 6 NaHSO4 + Energy

Propyl alcohol

The purple non-sulphur bacteria posses the pigment bacteriochlorophyll and accomplish photoreduction of
carbondioxide in presence of alcohol, organic acids, etc., e.g., Rhodospirillum sp. Rhodomicrobium sp and
Rhodopseudomonas sp.

6CO2 + 12CH 3CHOHCH3 Light → C6 H12O6 + 12CH 3COCH 3 + 6H 2O

The photoautotrophic bacteria thrive well below the surface of lakes and ponds where oxygen content is low
and reduced sulphur or other compounds are available.

(ii) Chemoautotrophic bacteria : Some bacteria manufacture organic matter form inorganic raw materials
(such as carbon dioxide) and utilize energy liberated by oxidation of inorganic substances present in the external
medium such as ammonia, ferrous ion, nitrates, nitrites, molecular hydrogen, etc. The energy liberated from
exergonic chemical reactions is trapped in the ATP molecules which is used in carbon assimilation to synthesize
organic matter. There are several types of chemoautotrophic bacteria which are commonly named after the
chemical compound they use as source of energy.

(a) Sulphur bacteria : These bacteria derive energy by oxidizing hydrogen sulphide or molecular sulphur.
Beggiatoa, a colourless sulphur bacterium oxidises hydrogen sulphide (H 2S) to water and sulphur. The energy

creleased is used up and the sulphur granules are deposited inside or outside the body of bacterial cell.
2H 2S + O2 → 2H 2O + 2S + Energy

The elemental sulphur is oxidized to sulphuric acid by denitrifying sulphur bacteria (e.g., thiobacillus

denitrifying) and the energy released during the process is utilized in reproduction, growth and synthesis of other
chemical substances.

2S + 2H 2O + 3O2 → 2H 2SO4 + Energy

These bacteria usually live at the mid-oceanicridge system (2.5 km below sea level). They generally live both
freely and with in the bodies of giant tube worms. They can even survive under extremely acidic conditions.
Examples of sulphur bacteria are- Beggiatoa, Thiobacillus, Thiothrix etc. They participate in the sulphur cycle in
nature.

(b) Iron bacteria : Some chemoautotrophic bacteria such as Gallionella, Sphaerotilus, Ferrobacillus, etc,
inhabit the environments where irons to ferric form. The Ferric ions are deposited in the form of soluble Ferric
hydroxide and the energy released during the conversion is used in the production of carbohydrates.

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4FeCO3 + O2 + 6H 2O → 4Fe(OH)3 + 4CO2 + Energy (81k.cal) .

(c) Hydrogen bacteria : These bacteria utilize free molecular hydrogen and oxidize to hydrogen into water
with the help of either oxygen or oxidize salts e.g. Hydrogenomonas. 2H 2 + O2 → 2H 2O + Energy (56 kcal).

(d) Amonifying bacteria : They oxidise protein and amino acid into NH3 (amonia). e.g. Proteus vulgaris,
Bacillus mycoids.

(e) Nitrifying bacteria : They oxidise ammonia to nitrites and then into nitrates.

NH 3 + O2 Nitrosomonas → NO2 + H 2O + Energy & 2NO2 + O2 Nitrobacter → 2NO3 + Energy .

(f) Denitrifying bacteria : They change nitrogen compound into molecular nitrogen. So that they reduce
fertility of soil e.g. Micrococcus denitrificans, Pseudomonas denitrificans.

(g) Methane bacteria : The bacterium Methanomonas utilizes methane as source of carbon and energy.

CH 4 + 2O2 → CO2 + 2H 2O + Energy .

(h) Methane producing bacteria : These are spherical or rod shaped bacteria which produce methane
(CH4 ) from hydrogen gas and carbon dioxide e.g. Methanobacterium.

CO2 + 4H 2 → CH 4 + 2H 2O .

The synthesis of ATP and reduction of carbon dioxide are linked reactions and used as sources of energy by
methanogens (e.g. Methanobacterium). Methane (swamp gas) is produced under anaerobic conditions and can be
used as a “biogas”, otherwise it is a pollutant that contributes to the green house effect and global warming.

(i) Carbon bacteria : These bacteria oxidize carbon monoxide into carbon dioxide and use the liberated
energy, e.g., Bacillus oligocarbophilus.

2CO2 + O2 → 2CO + Energy

c(iii) Heterotrophic bacteria : Most of the bacteria can not synthesize their own orgainc food. They are

dependent on external organic materials and require atleast one orgainc compound as a source of carbon of their
growth and energy. Such bacteria are called heterotrophic bacteria. Heterotrophic bacteria are of three types.
Parasites, Saprotrophs and Symbionts.

(a) Parasites : They obtain their organic food or special organic compounds required for their growth from
living cells of plants and animals. Some parasitic bacteria are relatively harmless and nonpathogenic, i.e., do not
produce disease in hosts. However, majority of parasitic bacteria are pathogenic and cause serious diseases in
plants and animals either by exploiting them or by secreting poisonous substances called toxins. Parasites contain
several chemical substances (i.e., enzymes, toxins and growth substances) to establish themselves in the host tissues.
Some of these chemicals are – agressins (to breakdown connective tissue), leucocides (to kill host phagocytes),
streptokinase (to prevent blood clotting) and cellulase (to digest cellulose).

Some examples of pathogenic parasitic bacteria which cause human diseases are

 Paratyphoid – Salmonella paratyphi

 Gastroenteritis – Salmonella sp. and Escherichia coli

 Dysentery – Shiegella dysenteriae, S. Sonnei, S. Boydii

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 Tularaemia (infected lymph nodes) – Francisella tularensis
 Influenza– Haemophilus influenzae
 Botulism (acute food poisoning) – Clostridium botulinum
Many pathogenic bacteria cause destructive diseases of economically important plants. The usual symptoms of
bacterial plant diseases are leafspots, rot, blight, wilt, gummosis, canker, scab and crown galls. Some of the common
plant diseases caused by bacteria are listed below.
 Black chaff of wheat caused by Xanthomonas translucens.
 Wilt of maize caused by Xanthomonas stewartii.
 Gummosis of sugarcane caused by Xanthomonas asculorum.
 Red stripe of sugarcane caused by Pseudomonas rubrilineans.
 Ring rot of potato caused by Corynebacterium.
 Canker of tomato caused by Corynebacterium michiganense.
 Leaf spot of Lady’s finger caused by Xanthomonas esculenti.
 Hairy rot of apple caused by Agrobacterium rhizogenes.
 Black knot of grapes caused by Pseudomonas tumefaciens.
(b) Saprotrophic bacteria : These bacteria obtain their nutritional requirements from dead organic matter
(such as animal excreta, corpses, fallen leaves, bread, fruits, vegetables, jams, jellies, etc.). These bacteria
breakdown the complex organic matter into simple soluble forms by secreting exogenous digestive enzymes. Then
they absorb the simple nutrient molecules and assimilate them. During assimilation, the bacterial cells oxidize the
organic matter to obtain the energy.
Aerobic break down of organic matter is called decomposition or decay. It is usually complete and not
accompanied by the release of foul gases. On the other hand, break down of organic matter in absence of oxygen is
not always complete and is accompanied by release of foul smell. Anaerobic break down of carbohydrates is usually

ccalled fermentation whereas that of proteins is called putrifaction. During putrifaction, the putrifying bacteria cause

degradation of proteins in absence of oxygen and convert them into simple ammonium compounds accompanied
by evolution of foul gases (hydrogen sulphide, methane, ammonia).

The decomposition caused by bacteria plays very important role in nature by recycling the matter in
ecosystems. It also provides inorganic molecules to photosynthesizing orgainsms. The decaying property of bacteria
is also used in ripening of cheese, ‘curing’ of tobacco and ‘retting’ of flax. Some free living bacteria (e.g.,
Azotobacter, Clostridium, Aerobactor, etc.) fix atmospheric nitrogen and improve the fertility of soil.

(c) Symbiotic bacteria : Symbiosis is the phenomenon in which the two orgianisms live in close association
in such a way that both the partners get mutual benefit from this association. For example, a very well known
nitrogen fixing bacteria – Rhizobium forms a symbiotic association with roots of leguminous plants (soyabean,
clover, alfalfa, etc.). Producing root nodules. These bacteria reside inside the nodules and reduce atmospheric
nitrogen (N 2 ) to ammonia. The fixed nitrogen is taken up by the plant. In return, the plant provides nutrients and
protection to bacteria.

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Another example of symbiosis is the presence of enteric bacterium Escherichia coli (E. Coli) in human
intestine. The bacteria shares our food but at the same time checks the growth of harmful putrefying bacteria and
releases vitamins K and B12 which help to produce blood components. Similarly cellulose degrading bacteria present
in the stomach of cows and goats help these animals in digesting grasses. In return, they get their nutritional
requirements.

Table of nutrition of Bacteria

Photoautotrophic Photolithotrophic Green sulphure bacteria
Photo-organotrophic (Chlorobium)

Nutrition Autotrophic Chemolithotrophic Purple sulphure bacteria
in bacteria Heterotrophic (Chromatium)
Chemoautotrophic Purple non-sulphure bacteria
(Rhodospirillum)
Chemo-organotrophic
Parasites Nitrifying bacteria
(Streptococcus, Clostridium) (Nitrosomonas, Nitrobacter)
Saprophytes Iron bacteria
(Bacillus mycoides) (Ferrobacillus)

Sulphur bacteria
(Thiobacillus)
Hydrogen bacteria
(Hydrogenomonas)

Methane bacteria

c(Methanococcus)
Symbionts
(Rhizobium leguminosarum)

(14) Spirochaetes : These are free inhabitants of mud and water, and are chemoheterotrophic bacteria.
These are spiral or helicoid in shape, covered by flexible cell wall and swim actively with flagella present at both
poles or ends. Many diseases are caused by them as Treponema pollidum causes syphilis, Leptospira causes
infectious Jaundice and Berrelia causes relapsing fever. Besides some spirochaetes are found in teeth.

(15) Archaebacteria : They are present in rumen of cattles. This is simplest and most primitive group of
bacteria. The cell wall of these bacteria is made of polysaccharides and proteins (peptidoglycans and muramic acid
are absent in cell wall). Further branched chain lipids are present in plasma membrane of archaebacteria, due to
which these can face extremes of conditions of temperature and pH. Archaebacteria are considered to be 'oldest of
living fossils'. Three main groups of archaebacteria are following.

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(i) Methanogens : These are strict anaerobic bacteria and mainly occur in muddy areas and also in stomach
of cattle, where cellulose is fermented by microbes. These are responsible for methane gas (CH4 ) formation in bio-
gas plants, because they have capacity to produce CH4 from CO2 or formic acid (HCOOH).

(ii) Salt lovers archaebacteria or halophiles : These are also anaerobic bacteria, which occur in extreme
saline or salty conditions (upto 35% of salt or NaCl in culture medium). A purple pigmented membrane containing
bacteriorhodopsin is developed in sun-light in these bacteria, which utilizes light energy for metabolic activities
(different from photosynthesis).

(iii) Thermoacidophiles : These are the bacteria which are found in hot sulphur springs (upto 80oC). As

against first two groups of archaebacteria, these are aerobic bacteria. These have the capacity to oxidize sulphur to
H 2SO4 at high temperature and high acidity (i.e. pH 2.0), hence given the name thermoacidophiles, i.e.,
temperature and acid loving. Some of these bacteria are able to reduce sulphur to H 2S under anaerobic
conditions.
Some of the most common and affective antibiotics are obtained from

cthe different species of the genus streptomyces. For example – Streptomycin
(16) Actinomycetes : It is a group of unicellular branched filamentous bacteria which resemble fungal

mycelia. They grow in the form of radiating colonies in cultures and therefore, commonly called ray fungi. They are

Gram +ve chemo-organotrophic, saprotrophic bacteria. Most species are

facultative anaerobic. These are filamentous bacteria (like moulds or fungi). Chain of conidia

These are generally present as decomposers in soil. These occur most

commonly and abundantly in soil, fresh water, manure, food products etc.

The filaments are aseptate (non-septate) branched and very thin (about 0.2

to 1.2 µm in width). The wall contains mycolic acid. They reproduce

asexually by means of conidia which produced at tips of filaments. The Conidophore

endospores are not formed. Most of these secrete chemical substances having

antimicrobial activities called antibiotics.

(from S. griseus), Chloromycetin (from S.venezuelae), Terramycin (from S. Fig : Actinomycetes : A mycelium
rimosus), Aureomycin (from S.aureofaciens), Erythromycin (from S. of streptomyces bearing conidia

erythreus), Neomycin (from S. fradiae), Carbomycin (from S. halstedii), Amphotericin B (from S. nodosus), etc.

Some species are pathogenic and cause diseases, e.g. Mycobacterium. Some common diseases in plants are
yellow ear rot of wheat (Tondu disease) caused by corynebacteriom tritici and scab of potato by streptomyces
scabies.

(i) Diseases in human beings
(a) Tuberculosis is caused by Mycobacterium tuberculosis hominis.
(b) Leprosy is caused by Mycobacterium leprae.
(c) Buruli's ulcer is caused by Mycobacterium ulcerans.
(d) Actinomycosis is caused by Actinomyces israelii.
(e) Diphtheria is caused by Corynebacterium diptheriae.

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(ii) Animal diseases

(a) Tuberculosis of cattle is caused by Mycobacterium bovis.

(b) Lumpy jaw is caused by Actinomyces bovis.

Note :  Zoogloea stage : The bacterial cells often become attached from end to end forming long

filamentous chain which are embedded in a mass of mucilage forming a scum layer on substratum. It is called as
Zoogloea stage.

(17) Rickettsias (Ricketts 1909) : They are Gram negative obligate pleomorphic but walled intercellular
parasites which are transmissible from arthropods. They are intermediate between true bacteria and viruses.
Rickettsiae require exogenous factors for growth. Cell wall is like typical bacterial wall. ATP synthesis is absent but
ADP is exchanged with host cell ATP. They have genome and size (0.3-0.5 µm ) smaller than true bacteria but have
a longer generation time. Internally the cells of rickettsias contain DNA as well as RNA in a ratio of 1 : 3 : 5. The cell
walls contain muramic acid and are sensitive to lysozyme. Flagella, pilli and capsule are absent reproduction occurs
by binary fission. The natural habitat of rickettsiae is in the cells of arthropod gut. they cause typhus group of fevers.
Spread by droplet method, lice, ticks, fleas, etc.

(i) Diseases in human beings

(a) Typhus fever is caused by Rickettsia prowazekii.

(b) Rocky mountain spotted fever is caused by Rickettsia rickettsii.

(c) Q fever is caused by Coxiella burnetti.

(d) Scrub typhus is caused by Rickettsia trutsugamushi.

(18) Importance of bacteria : Bacteria are our ‘friends and foes’ as they have both useful and harmful
activities.

Useful activities

(i) Decay of organic wastes : Many saprotrophic bacteria act as natural scavengers by continuously

cremoving the harmful organic wastes (i.e., dead remains of animals and plants) from man's environment. They

decompose the organic matter by putrifaction and decay. The simple compounds produced as a result of
decomposition and decay (viz., carbon dioxide, carbon monoxide, nitrates, sulphates, phosphates, ammonia, etc.)
are either released back into the environment for recycling or absorbed by the plants as food. Thus, the bacteria
play duel role by disposing of the dead bodies and wastes of organisms and by increasing the fertility of soil.

(ii) Role in improving soil fertility : Saprotrophic bacteria present in soil perform various activities for their
survival. Some of these activities improve the fertility of soil by formation of humus, manure, etc.

(a) Humus : The microbial decomposition of organic matter and mineralization results in the formation of
complex amorphous substance called humus. The humus improves the aeration, water holding capacity, solubility
of soil minerals, oxidation-reduction potential and buffering capacity of the soil.

(b) Composting : It is conversion of farm refuse, dung and other organic wastes into manure by the activity
of saprotrophic bacteria (e.g., Bacillus stearothermophilus, Clostridium thermocellum, Thermomonospora spp, etc.)

(c) Adding sulphates : A few sulphur bacteria (e.g., Beggiatoa) add sulphur into the soil by converting H 2S
into sulphates.

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(iii) Role in nitrogen cycle : Nitrogen cycle existing in nature, comprises of –

(a) Nitrogen fixation : Many free-living soil inhabiting bacteria such as, Azotobacter (aerobic), Clostridium
(anaerobic), etc. have ability to fix atmospheric nitrogen into ammonia. The other group of nitrogen fixing bacteria
live in symbiotic association with other plants. The most important symbiotic nitrogen fixing bacteria is Rhizobium
spp. The various species of Rhizobium inhabit different leguminous plants. For example, R. leguminosarium infects
soyabeans, etc. They develop root nodules and fix atmospheric nitrogen into ammonia in symbiotic association
with leguminous plants. The fixed nitrogen is partly taken up by the leguminous plants and metabolised. A part of
fixed nitrogen is diffused out into the surrounding soil.

(b) Ammonification : The nitrogenous compounds of the dead remains of plants, animals and their

NO2− + 1 / 2 O2 → NO3− + Energy ↑

(d) Denitrification : The nitrates and ammonia are converted to nitrous oxide and finally to nitrogen gas by
several denitrifying bacteria, e.g., Pseudomonas fluorescence, P. denitrificans, Bacillus subtilis, Thiobacillus
denitirficans, etc.

(iv) Sewage, disposal : Ability of anaerobic bacteria to purify the organic matter is used in the the sewage
disposal system of cities. The faeces are stored in covered reservoirs and allowed to purify. The solid matter is

cdecomposed into liquidy sludge which is passed through coarse filters. The effluent is finally purified and drained
excretory products are decomposed into ammonia by a number of bacteria and other microorganisms. The
conversion of nitrogenous organic compounds into ammonia is termed as ammonification. It is carried by many
ammonifying bacteria such as Bacillus ramosus, B. vulgaris, B. mycoides, etc.

(c) Nitrification : Many bacteria enhance the nitrogen fertility of soil by converting ammonium compounds
to nitrites (e.g., Nitrosomonas) and nitrites into nitrates (e.g., Nitrobacter).

The Nitrosomonas group oxidizes ammonia into nitrite –

NH + + 3/ 2 O2 → NO2− + H2O + H+ + Energy ↑
4

The Nitrobacter group oxidizes nitrite to nitrates –

out into the river or used as fertilizer in the fields. The common bacteria involved in sewage disposal are – Coliforms

(E. coli), Streptococci, Clostridium, Micrococcus, Proteus, Pseudomonas, Lactobacillus, etc.

(v) Role in Industry : Useful activities of various bacteria are employed in the production of a number of
industrial products. Some of these are given below –

(a) Lactic acid : Lactic acid is commercially produced from pasteurized whey (the watery part of milk)
through fermentation caused by Lactobacilus bulgaricus and L. delbrueckii.

(b) Curd : Curd is prepared from pasteurized milk by the process called curdling. It is initiated by adding a
starter culture of Lactobacillus bulgaricus and Streptococcus thermophillus, into the milk at 40°C. Lactobacillus
converts lactose to lactic acid whereas Streptococcus causes coagulation of casein due to acidity.

(c) Cheese : Preparation of cheese from the milk involves two main steps – first curdling of milk, and second
the subsequent ripening of solid curd by the use of different bacterial strains.

(d) Butter : It is prepared by churning of sweet or sour cream. The microorganisms responsible for
preparation of butter cream are – Streptococcus lactis and Leuconostoc citrivorumare. The characteristic butter

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aroma develops due to a volatile substance – diacetyl. It is produced by the action of streptococcus on pasteurized
milk.

(e) Retting process : Fibres of flax, hemp and jute are separated by the process called retting. During this
process the stems of the plants are submerged in water, where the bacterial activity results in the rotting of softer
parts. The tough bast fibres become loosened and easily separated from each other. These fibres are spun and
woven into various articles.

(f) Vinegar : Country made vinegar is a fermentation product of cane juice, molasses or fruit juices. It is
produced in two steps – first conversion of sugars into alcohols by alcholic fermentation carried by yeast, and the
second, conversion of alcohol to acetic acid by the action of bacteria Acetobacter (A. orieansis, A. acetic, A.
schuizenbachi, etc.). Vinegar is used in the preparation of pickles or in place of acetic acid. It is used as preservative
of meats and vegetables.

(vi) Role of bacteria in human being : E.coli (gram-ve) bacteria live in colon region of intestine of man
and other animals and play an important role in digestion process.

(vii) Medicinal uses

(a) Vitamins : Production of riboflavin (vitamin B2) involves the activity of bacterium – Clostridium
butyticum. The well known vitamin C (ascorbic acid) is produced from sorbital by the action of Acetobactor spp.

(b) Serum and vaccines : Many bacteria are used in the preparation of serums and vaccines. These
substances induce immunity to various diseases in man. Serums are effective against certain diseases like
diphtheria, pneumonia, etc., whereas the vaccines are effective against typhoid, smallpox, cholera, etc.

(c) Enzymes : Some bacteria live in the alimentary canal of herbivorous animals like cow, horse, goat, etc.
and help in the production of certain enzymes which digest the cellulose. The enzymes proteases are produced by
bacteria Bacillus subtilis. Similarly, the enzyme pectinase is produced by Clostridium sp, which is used in retting of
flax.

c(d) Antibiotics : These are the chemical substances produces by living microorganisms capable of inhibiting

or destroying other microbes. These are the products of secondary and minor metabolic pathways, mostly secreted
extracellularly by the microorganisms. These are used in controlling various infectious diseases.

At present more than 5000 antibiotic substances are known and approximately 100 are available for medicinal
use. The most important bacterium which produces maximum number of antibiotics is Streptomyces.

A list of some common antibiotics, their sources and their applications.
S. No. Antibiotic Obtained from Used against
A Streptomycin Streptomyces griseus
Gram-positive and Gram-negative bacteria, TB, tularemia (rabbit
B Actidine S. griseus fever), influenza, meaningitis, baciltary dysentery, etc.
C Chloromycetin S. venezuelae Plant diseases caused by fungi.
D Tetracycline S. aurefaciens Gram-positive and Gram- negative bacteria, typhoid, rickettsias
E Terramycin S. ramosus Gram-positive and Gram-negative bacteria, rickettsiae.
F Erythromycin S. erythreus Gram positive and Gram-negative bacteria.
Gram positive bacteria, whooping cough, diphtheria.

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G Neomycin S. fradiae Gram- positive, Gram negative and TB bacteria.

H Amphomycin S. carus Gram-positive bacteria,

I Amphotericin B S. nodosus Yeast, fungi

J Leucomycin S. kitasoensis Gram-positive bacteria.

K Trichomycin S. hachijoensis Yeast and fungi.

L Viomycin S. floridae Gram-positive, Gram-negative and TB bacteria.

M Bacitracin Bacillus subtilis Gram-positive bacteria

N Gramicidin B. brevis Gram-positive bacteria.

O Tyrothricin B. brevis Gram-positive and Gram-negative bacteria.

P Polymyxin B Aerobacillus polymyxa Gram-negative bacteria.
Harmful activities

(i) Food poisoning : Some saprotrophic bacteria cause decay of our food, i.e., they alter their normal form
and induce unpleasant aroma, taste and appearance. Some bacteria produce powerful toxins in food to cause
"food poisoning". Consumption of such food may cause serious illness or even death. Symptoms and causal
organism of some important types of bacterial food poisoning are listed below :–

(a) Botulism : It is caused by Clostridium botulinum. The main symptoms are vomitting followed by paralysis and death.

(b) Perfringens poisoning : It is caused by Clostridium perfringens. Symptoms appear in the form of
diarrhoea and acute abdominal pain.

(c) Staphylococcal food poisoning : It is caused by Staphylococcus aureus. Common symptoms are
nausea, vomitting and diarrhoea.

(ii) Spoilage of food : Some examples of bacterial food spoilage are listed below :–
(a) Salmonellosis in poultry and eggs is caused by Salmonella.
(b) Red rot of eggs is caused by Serratia marcescens.
(c) Greening on meat surface is caused by Lactobacillus and Leuconostoc.
(d) Black rot of eggs is caused by Proteus.
(e) Green rot of eggs is caused by Pseudomonas.

c(f) Souring of milk is caused by Lactobacillus and Streptococcus.
(g) Explosion of curd (gas production) is caused by Clostridium and Coliform bacteria.

(h) Ropiness (i.e., slimy milk) is caused by Klebsiella sp. Enterobacter spp.

(iii) Pollution of water : There are reports of epidemics of cholera, typhoid, jaundice and other infectious
diseases, which were caused by polluted water. Many pathogenic bacteria such as, Vibrio cholerae, Salmonella typhi,
Leptospira cetero-haemorrhagiae, etc. pollute water and make it unfit for drinking. These are eliminated by chlorination.

(iv) Deterioration of textiles : Some bacteria (e.g. Cytophaga, Vibrio and Cellulomonas) damage cellulose of textiles.

(v) Abortion :Bacteria like salmonella induce abortion in goats, horses, sheep etc.

(vi) Biological warfare : Some bacteria which cause diseases like anthrax, black- leg, tuberculosis etc, are
employed as secret war agents.

(vii) Denitrification : Denitrification bacteria like bacillus licheniformis, Pseudomonas aeruginosa convert
nitrates and nitrites into free nitrogen, thus responsible for the process of denitrification. Thus soil is depleted of
essential nutrient like usable form of nitrogen.

(viii) Putrefaction : It is the spoilage of protein in the absence of O2 by the putrefying bacteria e.g., Proteus, Mycoides.
(ix) Retting of fibres : It is the hydrolysis of pectic substances that bind the cells together.

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(x) Diseases : Bacteria are the causative agents of a large number of human diseases such as pneumonia,
typhoid, dysentery, cholera, plague, influenza, tetanus, diphtheria, tuberculosis, leprosy, syphilis, whooping cough
etc. They are also responsible for several plant diseases and animal diseases.

Most of the pathogenic bacteria are Gram – ve, rod-shaped (Bacillus) and non-spore forming.

Name of Disease Bacteria c

(a) In human beings Diplococcus pneumoniae
Pneumonia Salmonella typhosa
Typhoid Vibrio cholerae
Cholera Pasteurella pestis
Plague (Black death) Neisseria meningitides
Meningitis Neisseria gonorrhoeae
Gonorrhoea Treponema pallidum
Syphillis Bacillus coli
Diorrhoea E.coli
Gastroenteritis Corynebacterium diptheriae
Diptheria Mycobacterium tuberculosis
Tuberculosis Clostridium perfringens
Gangarin Leptospira ictero haemorrhagae
Jaundice Haemophilus pertussis or Bordetella pertussis
Whooping cough Clostridium tetani
Tetanus (lockjaw) Shiegella dysentriae
Bacterial dysentry Mycobacterium leprae
Leprosy
(b) In animals Bacillus anthracis
Anthrax Clostridium chauvi
Black leg disease
(c) In plants Pseudomonas solanacearum
Soft rot of potato Xanthomonas citri
Citrus canker Xanthomonas oryzae
Bacterial blight of paddy Corynebacterium tritici
Tundu disease in wheat Pseudomonas solanacearum
Potato wilt Erwinia amylovora
Fire blight of apple and peach Agrobacterium tumefaciens
Crown gall of sugar beet Xanthomonas compestris
Black rot of cabbage

Important Tips

• Robert Koch (1881) is the father of modern bacteriology.
• Bacteria are studied under bacteriology.
• Mycobacterium leprae is exception of koch's postulate because it can not grow in culture medium.
• Bacteria are unicellular prokaryotes. They were first seen by a Dutch lens marker, Anton Von Leeuwenhock (1683).
• Bacteria differ from animals in having a rigid cell wall.

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• A scientist named Gram, stained the bacteria with crystal violet and Iodine solution.
• After washing them with acetone or alcohol Gram+ bacteria retain deep violet or purple colour.
• Bacterial cell wall is made up by peptidoglycans and muramic acid.
• Father of modern antiseptic surgery. Joseph Lister.
• Insulin is the first hormone which obtained from genetically engineered bacteria.
• Free living N2 fixing bacteria – Azatobacter and polymyxa.
• Clostridium butyticum has been used in the synthesis of vitamin B.
• Commonsals : Those microorganism which are living in large intestine of human and that feed on undigested food without harming the

host are termed as.

• By the hanging drop slide we can see movement of bacteria.
• Capsule is made up by polysaccharides and polypeptides.
• Mesosomes contain oxidative enzymes of electrons transport system. It is the folding of plasmamembrane which also help in respiration

so they are called chondriods.

• External DNA enters in bacteria through mesosomes.
• In the bacterial cystoplasm, membranous organelles like (mitochondria, chloroplast, ribosome, endoplasmic, reticulum, Golgy body, etc.)

are absent.

• In bacteria flagella may be present, PS II absent, photosynthesis is a nonoxygenic.
• In the cytoplasm 70 S ribosomes present. Bacteria also contain fats, glycogen, protein and photosynthetic pigment (carotenoids).
• True nucleus is absent in them. Their nucleus is called nucleoid.
• Histone proteins are absent in bacterial cell (Prokaryotic cell).
• Flagella of salmonella bacteria contain H-antigens.
• Bacterial flagella is composed of 1 or 3 tubuline fibril organisation against 9+2 fibril organisation in eukaryotes.
• Bacteria – have two important factors located on plasmid. (1) F.factor (sex factor). (2) R-factor (resistance factor).
• Gram +ve bacteria (Bacillus and Clostridium) produce resting spores called endospores which are formed in unfavourable conditions.
• Transformation process is reported by Griffiths (1928) in mice.
• Polyribosome always attached with m RNA.

c• Volutin granules are the source of energy in bacteria.

• Transduction was first reported by Zinder and Lederberg in (1952). In this process DNA of a bacterial cell transfer to another bacterial
cell by Bacteriophage.

• Conjugation – was discovered by Lederberg and Tatum. In this process two different types of bacteria are connected by conjugation. The
bacterium which contains F-factor is called F+/donor, the other bacterium which lacks this factor is called F– or the recepient.

• Iron bacteria – they oxidise ferrous compound to ferric forms eg. Thiobacillus.
• Chemoautotrophic bacteria – these bacteria oxidise a number of inorganic compounds to obtain energy for the assimilation of CO2. they

cannot make use of light energy.

• Escherichia coli (E. coli) is a facultative aerobic bacteria found in the colon region of intestine of human being. this bacterium was
discovered by Escherisch (German scientist).

• Chemically E.coli has about 70% H2O, 15% proteins, 6% RNA, 1% DNA. 2% Lipid, 3% carbohydrates, etc.
• Rhizobium bacteria found in a symbiotic relationship with leguminous plant. They fix N2 in root nodule from atmosphere. It has nifgene.
• Non symbiotic anaerobic non-photosynthetic N2 fixing bacteria is clostridium.
• Azotobacter is found freely in the soil as saprophyte. It is estimated that such bacteria are capable of adding 5-25 Kg. of nitrogen per acre

per year.

• Nitrifing bacteria transform NH 3 into nitrates.

• Bacterial size ranges between 2 − 5µ , Smallest bacterium – Dialister pneumosintes. Largest bacteria are – Spirillum laid.

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• Plasmid is the extra DNA structure. They can independently replicate. Plasmid are not essential for normal life process.
• Eukaryotic flagella is formed of tubulin protein while bacterial flagella is made up of flagellin protein.

Mycoplasma.

Mycoplasmas were discovered by E. Nocard and E. R Roux (1898). They were first isolated from bovine sheep

suffering from pleuropneumonia. They are often designated as Lipoprotein
pleuropneumonia–like organisms (PPLO). These organisms were later membrane
(3 Layers)

put under the generic name mycoplasma by Nowak (1929). In 1966 Metabolites

international commitee of Nomanclature of bacteria, placed Ribosomes

mycoplasmas under the class mollicutes, which consists of two genera
Mycoplasma and Acholeplasma. These are the simplest unicellular non-
motile known aerobic prokaryotes without cell wall. So that they can
change their shape therefore called Jockers of microbiological park. They
are considered to be intermediate between bacteria and viruses. They
have smallest living cells of prokaryotes. They are known to cause a
number of diseases in human beings, animals and in plants. Mycoplasma
can grow out side the host cell. Thus it is clear that mycoplasma are not
obligate parasites like viruses. They are gram-negative.
(2) Structure : They are one of simplest prokaryotic organisms. Their size varies from 0.1 – 0.15 µm. They Soluble
lack the cell wall. Due to the absence of the cell wall, these organisms are highly elastic and readily change their protein
shape; hence the mycoplasmas are irregular and quite variable in shape. This nature is called pleomorphism. They
may be coccoid, granular, pear–shaped, cluster–like or filamentous. Mycoplasma cells are covered with three DNA

clayered plasma memberane. Unit membrane is made up of lipoprotein. Normally there are no mesosomes but in Soluble RNA

Fig : Mycoplasma–showing structural details

(1) Distribution : Mycoplasmas occur in soil, sewage water, different substrates, and in human beings,
animals and plants. They have also been found in hot water springs and other thermal environments. They are the
frequent contaminants in tissue cultures rich in organic matter.

stationary phase, some time mesosomes are also present on plasma membrane. They lack the well organised

nucleus, endoplasmic reticulum, mitochondria, plastids, golgi bodies, centrioles, flagella, etc. The genetic material is

present in the form of a nucleoid. The latter consists of a single, circular, double–stranded molecule of DNA, without

a nuclear envelope. Unlike other prokaryotes, it is coiled throughout the cytoplasm. The cytoplasm contains the

ribosomes which are 70S. It also contains RNA, proteins, lipids and many kinds of enzymes used in biosynthetic

reactions. Lipids include cholestrol and cholestrol esters which are characteristic of animal cells and are not found in

true bacteria and cyanobacteria. The amount of DNA and RNA in the cells is usually less than half of that which

occurs in other prokaryotes. There is 4% DNA and 8% RNA. It is perhaps the lowest limit required for a cellular

organism. Sterol is must compulsary for growth of mycoplasma. Mycoplasmas are Gram–negative.

(3) Physiology and reproduction : Mycoplasmas are usually non–motile. They are sensitive to tetracycline
and resistant to penicillin. These are destroyed usually by treatment of heat at 50o C for 6 hours mycoplasma are
osmotically inactive. Some forms, show gliding movements. Mycoplasmas are heterotrophic in their mode of
nutrition. Some of them are saprotrophs, but most of them are parasitic on plants and animals including man. They

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reproduce by budding or binary fission. Fragmentation specially in filamentous forms. Besides this, Mycoplasma
reproduces by elementary cell bodies also. It is also called baby particle. It is a kind of vegetative reproduction.

Culture of mycoplasma : These can be cultured in non-living medium, although they grow well in living
medium, contain chick tissue. In non-living medium, they require agar-agar and blood serum.

(4) Economic importance : Mycoplasma cause serious diseases in human beings, animals and plants. Some
of these are given below.

(i) Diseases in Human beings : Mycoplamsa hominis causes pleuropneumonia, inflammation of genitals
and endocarditis, etc. Mycoplasma pneumoniae causes primary a typical pneumonia (PAP), haemorrhagic
laryngitis, etc. Mycoplasma fermentatus and M. hominis cause infertility in man, otitis media (inflamation of middle
ear).

(ii) Diseases in animals : Mycoplasma mycoides causes pneumonia in cattle. Mycoplasma bovigenitalum,
causes inflamination of genitals in animals. Mycoplamsa agalactia causes agalactia of sheep and goat.

(iii) Diseases in plants : Common Mycoplasmal diseases of plants are: Bunchy top of papaya, witches'
broom of legumes, yellow dwarf of tobacco, stripe disease of sugarcane, little leaf of brinjal, clover phylloidy, big
bud of tomoto, etc. Mycoplasma are the smallest organisms which produce diseases in plants.

(5) Difference between L-form bacteria and mycoplasma : In the culture of bacteria, some bacterial cells
are developed which are without cell wall and such bacterial cells which are without cell wall are known as L-form
bacteria ('L' for Lister institute, where these were reported).

Important difference between L-form bacteria and mycoplasma is that under optimum nutritional conditions.
L-form bacteria will develop cell walls whereas mycoplasma will never develop cell wall.

Important Tips

• Mycoplasma is the smallest cell of prokaryotes.

c• Mycoplasma are also called Joker of plant kingdom.

• They lack cell wall. They are covered by three layers of plasmamembrane
• Mycoplasma are sensitive to tetracycline and resistant towards penicillin.

• Bleb and infra bleb – These are peculiar structures which are formed at both ends during binary fission in mycoplasma and as soon
as binary fission is complete, these structures disappear. So the significance of bleb and infra bleb is not known.

Cyanobacteria.

The new name of cyanobacteria has been given to myxophyceae or cyanophyceae. Cyanobacteria form a
group of ancient Gram negative, photosynthetic prokaryotes. Many botanists prefer to call them blue-green algae.
They have survived successfully for about 3 billion years. They may cause water blooms.

(1) Distribution : Cyanobacteria are predominantly fresh water forms, a few are marine. They are found
growing even under extreme situations such as in hot springs and the undersides of icebergs. The fresh water forms
occur in ponds, lakes, pools and reservoirs. They impart unpleasant taste and smell to the water. One species of
cyanobacteria containing red pigment (Trichodesmium erythracum) flourishes in Red Sea and is responsible for the

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red colour of its water. Some grow in the soil and help in fixation of nitrogen and utilize it in metabolism. Nostoc
colony is found into the thallus of Anthoceros. Colonies of Nostoc and Anabaena grow in paddy fields. Some live in
symbiotic relationship with other organisms. In Oscillatoria filaments show oscillating motion.

(2) Organisation of Thallus : The organisation of thallus ranges from unicellular to branched heterotrichous forms.

(i) Unicellular forms, e.g., Chroococcus, etc.

(ii) Unicellular polar thalli with a definite base and apex, e.g., Dermocarpa, Chamaesiphon, etc.

(iii) Multicellular colonial forms, e.g., Gloeocapsa, Trichodesmium, Merismopedia, Microcystis, etc.

(iv) Simple unbranched filamentous forms without heterocysts and akinetes, e.g., Arthrospira, Oscillatoria,
Spirulina, Phormidium, Lyngbya, Symploca, Microcoleus, Schizothrix, etc.

(v) Simple unbranched filaments with heterocyst, e.g., Nostoc, Anabaena, Aulosira, Anabaenopsis,
Cylindrospermum, etc.
c(i) Cell wall : The cell wall completely surrounds the
(vi) Unbranched heterocystous filaments with base and apex, e.g., Rivularia, Gleotrichia, etc.

(vii) Heterotrichous filaments with false branching, e.g., Scytonema, Plectonema, etc.

(viii) Heterotrichous filaments with true branching, e.g., Haplosiphon, Stigonema, etc.

(3) Oxygen revolution : They are said to be earliest oxygenic photosynthesizers. Due to their activity atmosphere
turned aerobic, thus providing favourable conditions for the evolution of aerobic bacteria and other eukaryotes.

(4) Symbiotic forms : There is a long list of cyanobacteria which are found in symbiosis with plants and
animals. They may be associated with lichens. Many members are associated with liverworts, mosses, ferns,
flowering plants, fungi, protozoa, sponge, shrimp and sometimes a mammal. They have been reported in
bryophytes like Anthoceros, Anabaena cycadeae is found in coralloid roots of cycads.

(5) Movement of cyanobacteria : Flagella are completely absent but the movement occurs in some genera
by special gliding motion. Such movements are connected with the secretion of mucilage. The genus oscillatoria
exhibits pendulum like oscillating movement of its anterior region.

(6) Ultrastructure : The cyanobacterial cell is normally larger than a bacterial cell. Like a bacterial cell, it
consists of a tiny mass of protoplast surrounded by cell wall. It is differentiated into cell wall, cytoplasm and a
nucleoid.

Mucilaginous sheath

protoplast. Cell wall is made up of muramic acid, Cell wall

Lipopolysaccharides, Glucosins, Glutamic acid and α- Plasma membrane
diaminopimalic acid. It is a thin structure made up of cellulose Lamellae

and peptidoglycan. External to the cell wall is a mucilaginous Protien
sheath. It has a great water absorbing and retaining capacity. The granule

sheath is made up of reticulated arranged microfibrils within an Phycogl oscoes
amorphous matrix. The fibrils may be composed of pectic acid DNA
and mucopolysaccharides, sheath may be thin or thick, hyaline Plasma membrane

or pigmented, homogenous and stratified. The cell wall is firm Photosynthetic Nucleoid
and rigid. It is two layered. The outer layer is convoluted and Lamellae
Fig : A cyanobacterium cell

inner layer is smooth. The inner layer is made up of peptidoglycan similar to bacterial cell wall.

(ii) Cytoplasm : The cell wall is followed by plasma membrane made up of lipid and proteins. Inner contents
of the cell can be distinguished into two regions-outer pigmented region called chromatoplasm and central hyaline
centroplasm. The membrane bound structures like true mitochondria, chloroplasts, endoplasmic reticulum, golgi
bodies, true vacuoles, etc. are absent. The photosynthetic pigments are located in broad sheet like lamellae, called

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thylakoids. The thylakoids are restricted to peripheral region of cytoplasm usually arranged in two or more parallel

stacks. Some lipid globules occur within the thylakoids whereas phycobilisome particles are attached to their

surfaces. Some authors suggest that these lamellae also provide the sites for cellular respiration. The photosynthetic

pigments present in the cell are – chlorophyll a, β carotene, Myxoxanthophyll, myxoxanthin, C-phycocyanin and C-

phycoerythrin. The C-phycocyanin is blue and C-phycoerythrin is red in colour. If C-phycocyanin is more as

compared to C-phycoerythrin, it gives characteristic blue- green colour to the algae. Other cellular inclusions are gas

vacuoles, cyanophycin granules, volutin granules, β - granules (lipid droplets), polyhedral bodies, 70s ribosomes,

etc. The gas vacuoles are common in planktonic forms. They are the vesicles filled with gas and bounded by single

membrane. They serve to regulate the buoyancy of the planktonic forms. In diffuse or low light intensities, they are

large and help to bring the cyanobacteria at the surface. Cyanophycin granules are made up of stored protein.

Volutin granules store phosphate, α-granules contain cyanophycean starch, β-granules contain lipid droplats.

(iii) Nucleoid or genophore : It lacks a definite nucleus. The nuclear material consists of a single
chromosome made up of a naked strand of DNA helix which lies in the centre. DNA is not associated with histone
proteins. In this respect, they resemble the circular chromosome of bacteria. The nucleolus is absent and the
nucleoid is not bounded by a nuclear membrane (This type of nucleus called incipient nucleus).

(7) Nutrition : Because of the presence of chlorophyll–a, cyanobacteria synthesis their own food from carbon
dioxide and water in the presence of sunlight. Certain cyanobacteria like Nostoc and Anabaena fix atmospheric
nitrogen in the presence of oxygen. They are obligate photoautotrophs. They do not grow in darkness.
Cyanobacteria are the earliest photosynthesizers which made the earth's atmosphere aerobic.This provided the
suitable condition for the evolution of aerobic bacteria and eukaryotes.

(8) Reproduction : Cyanobacteria reproduce asexually by fission and fragmentation. Unicellular forms
multiply by binary fission flagella are absent in vegetative as well as reproductive phase. The filamentous forms
reproduce by fragmentation of their thallus into hormogonia (as in Nostoc and Oscillatoria). Heterocysts and
akinites are used in propagation. These serve as vegetative means of
propagation. Except oscillatoriaceae all cyanophycean member contain
heterocyst. It is a special type of cell of cynobacteria. Food material,
stored in them in the form of cyanophycean starch.

c(9) Nitrogen fixation in cyanobacteria : Like many bacteria,
several forms of blue green algae have the capacity to fix atmospheric Heterocyst

nitrogen into nitrogenous compounds. This capacity is restricted to

filamentous heterocystous forms like Nostoc, Anabaena, Aulosira,

Mastigocladus, scytonema and calothrix. Under anaerobic conditions,

some nonheterocystous forms can also fix atmospheric nitrogen

(Oscillatoria, Plectonema, Phormidium). This additional capacity of

N 2 − fixation along with CO2 − fixation makes them truely autotrophic

plants. In this sense, they are considered to be largely responsible for Fig : Nostoc Habit and Heterocysts
the maintenance of soil fertility in tropical and temperate regions. Some

species of blue-green algae have a great contribution to increase the fertility of rice fields in tropical countries like

India (e.g., Anabaena, Aulosira, Zolypothrix).

Biochemistry and mechanism of nitrogen fixation in blue- green algae have been studied in detail. The
radioactive tracer technique and other. Researches have shown that the atmospheric dinitrogen (N ≡ N) is reduced

to ammonia in the presence of a reducing agent. The reaction is a stepwise process and is catalyzed by the nitrogen
fixing enzyme- nitrogenase utilizing energy. The enzyme nitrogenase works under anaerobic conditions.

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The fixed nitrogen can be utilized in its own metabolism by blue-green algae. The nitrogenous compounds
come to the soil after death and decay of blue –green algae or by direct leaching of the soluble nitrogenous
compounds. In soil, the nitrogenous compounds are available for use by higher plants.

As stated earlier, the enzyme nitrogenase works anaerobic conditions. The thick walled heterocysts provide a
suitable anaerobic environment for nitrogenase, even under aerobic conditions. Under anaerobic conditions both
heterocystous and non- heterocystous forms can fix nitrogen because of the proper functioning of the nitrogenase.
Leghaemoglobin present in leguminous root nodules that act as oxygen scavenger because nitrogenase works under
anaerobic condition.

(10) Economic importance
(i) Useful activities

(a) Spirulina is cultivated in tanks as a protein rich food for fish and other animals.

(b) Some cyanobacteria like Nostoc, Anabaena, Scytonema etc. increase the soil fertility by fixing the free
nitrogen of the atmosphere. So that it is used as a biofertilizer.

(c) Reclamation of soil : Certain cyanobacteria like Nostoc commune, scytonema ocellantum, Aulosira
fertissima are used for reclamation of usar (sterile alkaline) soil. These organisms secrete acidic chemicals which
counteract the alkalinity of the usar soil.

(d) Food : Nostoc community are as food by Chinese and South Americans. Food is called yoyucho.

(e) Prevention of growth of mosquito larva : Few species of Anabaena and Aulosira are inoculated in
ponds to check the development of mosquito larvae.

(f) Green manure : In sambhar lake of Rajasthan, Anabaena and Spirulina are produced in large number.
Local people use it as green manure.

(g) Soil erosion : Some cyanobacteria, such as Anabaena, Lyngbya etc. help in conservation of soil, thus

cchecking soil erosion.
(h) Plant succession : few cyanobacteria located inside lichens help in plant succession due to their growth
on barren land.
(ii) Harmful activities

(a) Spoilage of drinking water : Forms like Anabaena not only spoil the taste of drinking water but also
produce toxic effect.

(b) Diseases : Skin infections may be caused by cyanobacteria like Lyngbya.

(c) Toxin secreting cyanobacteria : They are mainly responsible for water blooms. By the death and
decomposition water gets contaminated and unfit for normal use some cyanobacteria like Ribularia release toxins
which is harmful for aquatic fauna.

NOSTOC –

Systematic position –

Kingdom – Plantae
Thallophyta
Sub kingdom –

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Phylum – Cyanophyta

Class – Myxophyceae (Cyanophyceae)

Order – Nostocales

Family – Nostocaceae

Genus – Nostoc (Nostoc name is given by Vaucher)

Common Name – Fallen stars

(11) Habitat : This is an alga of both terrestrial and aquatic habitats. Terrestrial species grow commonly either

on bare soil or intermingled with plant parts. Sometimes aquatic species submerged lying on the bottom of the

pools, or attached to a substratum and some time free floating Nostoc is found in a colony. All colonies are covered
by mucilaginous covering. Nostoc associate with fungi to form lichens.

They behave as “space parasites” in the thalli of filamentous Anthoceros.

(12) Morphology : The Nostoc plant is filamentous and the trichomes are unbranched and appear
moniliform. Individual cells are mostly spherical but some times barrel shaped or cylindrical also. Single filament of
Nostoc without mucilagenous sheath is called Trichome. Trichome with mucilaginous sheath is called filament.
Individual
Common sheath Mucilage
csheath
Sheath

Cell wall Central body Hetrocyst
Chromoplasm
Heterocyst

Akinite Sheath Pore
C
Pseudo vacuole Cyanophycin
A Heterocyst A granules

Polar nodule
B

B

Nostoc : species

All the cells of the trichome are similar in structure but at some intervals are found slightly larger rounded light
yellowish thick walled cells called as heterocysts it can fix N2. It is formed from normal cell when dim light is present.
Trichome mostly breaks near heterocyst and forms hormogonia and thus they help in its multiplication.

The heterocysts are intercalary and posses a very thick outer wall. Each heterocyst is connected with vegtative
cells, on two sides through the prominent pores in to the wall. Which later on are occupied by a refractive
cyanophycean granule called polar nodule.

Each cell of Nostoc has a primitive nucleus or (prokaryotic).

(13) Reproduction : There is no sexual reproduction in Nostoc but it reproduces asexually by the following methods.
(i) Hormogonia : The filaments break at number of place into smaller pieces, called as hormogonia. By
decay of an ordinary cell they slip out of the mucilaginous sheath and grow into new plants.

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(ii) Resting spores or akinites : Under certain condition some of the vegetative cells enlarge and
accumulate food material and develop thick walls. These are called akinites. The akinites germinate after a period of
rest and their contents are liberate out through a pore. Protoplast by further division forms the new filament.

(iii) Heterocysts : In exceptional case heterocyst may become functional and on germination develops a new colony.
(iv) Endospores : Nostoc microscopium, Nostoc commune.
(14) Economic importance
(i) Many species of Nostoc fix atmospheric nitrogen and thus increase the soil fertility. Heterocysts “the unique
structure” of Nostoc filament function as sites for nitrogen fixation. In heterocysts the free nitrogen (N2) of the air is
converted into (NO3) nitrate.
(ii) Reclamation of alkaline “usar soils” can be done by employing some species of Nostoc.
(iii) Nostoc use as vegetable in China and Japan.

Important Tips

• Cyanobacteria form a group of ancient gram negative photosynthetic prokaryotes.
• Nostoc colonies are found into the thallus of Anthoceros.
• Heterocyst is the special cell in cyanobacteria which can fix to N2 from atmosphere.
• Some blue green algae live in protozoans are called “cyanellae”.
• The blue-green colour of cells is due to the presence of phycocyanin pigment.
• Blue green algae were first placed under algae but now they are kept under bacteria
• BGA produce oxygen during photosynthesis so these are called “oxyphotobacteria”.
• A filament without mucilaginous sheath is called trichome.
• In cyanobacteria, flagella are absent, PS-I and PS-II are present, photosynthesis is oxygenic.
• Thick walled hormogonia or multicellular akinite found in blue green algae are called hormocysts.
• Symbiotic N2 fixing algae is Anabaena.
• Trichodesmium a non-heterocystous nitrogen fixing colonial aerobic cyanobacterium which occurs as phytoplankton throughout

ctropical and subtropical oceans and fixes atmospheric nitrogen while evolving photosynthetic oxygen.

Viruses.

The term 'virus' has been derived from Latin, which means poison or venom or viscous fluid. These are highly
controversial group of microscopic objects (smaller than bacteria, mycoplasma, nostoc, etc.) and are most perfect
obligate intracellular parasites of the world. They remain inactive outside a living host but become active inside the
host and multiply in it. They represent a transitional form of life between non–living and living world. Nowadays,
these are defined as "Viruses are infectious nucleoproteins". The definition given by Green (1935) states that the
viruses are the smallest units showing reproductive properties considered typical of life.

According to Bawden (1949), "Viruses are obligate parasites, too small to be seen."
Luria (1953) defined virus as "Sub-microscopic entities capable of being introduced into specific living cells
and reproducing inside such cells only. "Single virus is called 'Virion', most of the plant virus are RNA virus. Must of
the animal virus are DNA virus.

(1) Important discovery of virus

(i) Carolous causius (1576) recorded first viral disease in tulips.

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(ii) A. Mayer (1886) found a disease in tobacco caused by virus and called it tobacco mosaic disease.

(iii) D. Ivanowski (1892), a Russian Botanist, discovered the infectious nature of the viruses. He was the
person, who discovered the virus. He found that juice of an infected tobacco when filtered through bacteria–proof
filter, caused disease in healthy plants of tobacco.

(iv) Beijerinck (1898) repeated the same experiment and called it infectious fluid–“contagium vivum
fluidum”, therefore, he first used the word Virus.

(v) Popper (1908) reported poliomyelitis virus.

(vi) W. Twort (1915) and D. Herelle (1917) discovered bacteriophages, a kind of virus which infected

bacteria and destroyed them.
c(c) They possess high specific gravity unlike living organisms.
(vii) M. Schelsinger (1933) for the first time isolated a virus by using the technique of ultracentrifugation

(viii) W. M. Stanley (1935) first time isolated tobacco mosaic virus (TMV) in crystalline form and showed
that crystals were made up of proteins. Nobel prize was awarded to him for this work.

(ix) Bawden and Pirie (1938) purified TMV and found it to be a nucleoprotein containing RNA.

(x) Saffermann and Morris (1963) discovered Cyanophages that infect blue–green algae.

(2) Nature of viruses : Viruses are regarded as intermediate spike
between non-living entities and living organisms. It is very difficult to Lipo protein envelope
ascertain whether they are living or non-living. Some characters of
viruses suggest their non-living nature whereas many other characters Fig : Influenze virus
suggest their living nature. The two views are listed below –

(i) Viruses are non-living : The following characters state that they are non-living.

(a) Viruses have no complete cellular structure. They are not surrounded by cell membrane or cell wall.

(b) They do not show cellular metabolism and lack respiration.

(d) Viruses are active only when they are inside the living host cells. Out side the host, they are good as

chemical substances. Thus, they do not have their independent existance.

(e) Stanley (1935) isolated the viruses in a crystalline form and kept for a long period. In this form they neither grow
nor reproduce but remain in a crystalline form. This phenomenon has not been observed in any living organism.

(f) The viruses can be precipitated just like chemical substances.

(g) Postulates of Robert Koch are not true for the viruses. Virus cannot grow in “invitro” condition in lab.

(ii) Viruses are living organisms : The following characters state that they are living organisms –

(a) They have definite shape and morphology like that of a living organism.

(b) They possess genetic material (DNA or RNA), which determine their structure and development. Genetic
material passes from generation to generation in usual manner.

(c) All viruses are intracellular obligate parasite and attack specific hosts. The bacteriophages recognise the real
bacterial surface. The viruses produce characteristic symptoms on their particular host.

(d) They show property of mutation.

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