Introduction to Extracellular Polymeric Substances (1)

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1.0 INTRODUCTION

Extracellular polymeric substances (EPS) is a highly hydrated polymers, which mainly
composed of polysaccharides, proteins and DNA that arise from a wide range of
microorganism. It is essential for microbial life as well as providing an ideal environment for
various chemical reactions, nutrient entrapment and protection against environmental stresses.
(Costa, Raaijmakers, & Kuramae, 2018). EPS can be produced by both prokaryotes (eubacteria
and archaebacteria) and eukaryotes (phytoplankton, fungi and algae). The composition and
structure of EPS vastly vary; as it can be either homopolysachharides or heteropolysaccharides.
(Singha, 2012).

Generally, the bacteria which produce EPS can be found in the environment that have a high
amount of organic substances. These bacteria can be isolated using complex or chemically
defined media, where they produce colonies with mucoid or watery surfaces, with glistening
and slimy appearances on the agar plate, and hence can be detected macroscopically. Singha
(2012) in his journal states that the production of EPS “can be influenced by bacterial growth
phase, medium composition, pH and temperature”. The production of EPS commonly take
place during active sugar consumption. (Singha, 2012)

2.0 CONTENT

2.1. Xanthan gum

Xanthan gum is an example of extracellular polymeric substances, a water-soluble
exopolysaccharide, which can be produced using gram negative bacterium Xanthomonas
campestris by aerobic fermentation. It was first discovered by The National Center for
Agricultural Utilization Research in 1963 and was studies widely as its properties would allow
it to supplement other known natural and water-soluble gums. (Palaniraj & Jayaraman, 2011)

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Commercially, xanthan gum powder is a yellowish material, which is soluble in both hot and

cold water. Once dissolved, this solution can remain stable for several months at room

temperature. Due to its secondary structure, xanthan is quite stable against degradation by acids

or bases, heat treatments, freeze-thaw cycles, enzymes and long mixing. (Nussinovitch, 1997)

2.1. Xanthomonas campestris

Xanthomonas belongs to the family of Pseudomonadacea. It is a genus of gram-negative,
aerobic, short rod-shaped bacteria. It includes several producers of xanthan gum which are
mainly plant pathogens.

2.2. Production of Xanthan gum

The production of Xanthan gum started by preserving the selected microbial strain for a long-
term storage. Next, a small amount of the preserved culture is expanded by growing it on a
solid surface or in liquid media in order to obtain an inoculum for large bioreactors. The growth
of microorganism and production of xanthan are highly influenced by several factors, including
the type of bioreactor used, the mode of operation, medium composition as well as the
conditions of the culture. Upon the completion of the fermentation process, the broth will
contain xanthan, bacterial cells and many other chemicals. Following that, recovering of
xanthan will be done by removing the cells via filtration or centrifugation. Further purification
may include precipitation, addition of certain salts and adjustments of pH. Once the
precipitation process completed, the product is mechanically dewatered and dried. The product
is the milled into containers with low permeability to water. (Palaniraj & Jayaraman, 2011)

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Figure 1. Production of Xanthan gum in conventional stirred tank fermenter (Rosalam and England,

2006)

2.3. Application of Xanthan gum

Food Industry

Xanthan gum has been majorly used in food industry as emulsifier and thickening agent in a
variety of products such as juice, fruit pulp, sauces and gravies. In order to reduce its production
cost, xanthan gum is used in combination with other gums such as locust bean gum or guar.
(Lopes, et al., 2015). In the bakery production, xanthan gum is used in order to increase water
binding during baking, storage and extends the shelf life of these baked goods. In addition,
xanthan can also be used to replace egg-white in soft baked goods. (Palaniraj & Jayaraman,
2011)

Oil industry

In petroleum industry, xanthan gum is used for oil drilling, fracturing, pipeline cleaning and
others. It is also useful as an additive in drilling fluids, due to its excellent compatibility with

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salt as well as its resistant to thermal degradation. Other than that, xanthan can also be used for

the enhanced oil recovery (EOR) application. (Singhal, 2011)

Chemical Industry

Xanthan have a shear thinning characteristic in which can be used in paint industry. Paints
which contain xanthan are highly viscous at low shear rates, therefore it will not drip from the
brush. In addition, xanthan is also used in jet injection printing due to its ability to disperse and
hydrate rapidly, is non-polluting and gives a good colour yield. (Singhal, 2011)

2.4. Company that produces xanthan gum

One of the companies that sold xanthan gum is DSM, which is a global purpose-led, science-
based company that specialize in nutrition, health and sustainable living. Other than supplying
xanthan gum, they also supply gellan gum, welan gum and pectin from 3 production facilities.
(DSM Hydrocolloids, n.d.). Other than that, ‘Foodchem International Corporation’, a Chinese
leading company are also one of the companies that sold Xanthan gum. They has been
supplying and exporthing Xanthan gum from China. (Foodchem International Corporation,
2006)

Figure 2. Xanthan gum powder in a bottle container.(Foodchem International Corporation, 2006)

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3.0. CONCLUSION

Xanthan is one of the most commercially produced industrial gum, with an annual worldwide
production of 30,000 tons, and corresponds to a market of $408 million (Kalogiannis,
Gesthimani, Maria, Dimitros, & George, 2003). Due to its high demand, studies have been
done for development and improvement of xanthan gum production. Other than that, other EPS
has also been studied to find a cheaper and better EPS, which in turn could replace this Xanthan
gum. This is because, although xanthan gum have a major markets for food and related
industries, there are still some improvements that can be done in order to obtain a better quality
xanthan at a faster production time.

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4.0. REFERENCE LIST

Costa, O. Y., Raaijmakers, J. M., & Kuramae, E. E. (23 July, 2018). Microbial Extracellular
Polymeric Substances: Ecological Function and Impact on Soil Aggregation. Frontiers
in Microbiology, 9.

DSM Hydrocolloids. (n.d.). DSM Food Specialist. Retrieved from
https://www.dsm.com/corporate/about/business-entities/dsm-food-specialties/dsm-
hydrocolloids.html?WT.srch=1&WT.mc_id=SEA_Google_1.0-DSM-Hydrocolloids-
searches_Welan&gclid=Cj0KCQiAgMPgBRDDARIsAOh3uyLbknSKYeShpnWaO
wgpAMaHN_Z2ANA55mXKKgQ0gE19Q2INBZATMHgaAnpA

Foodchem International Corporation. (2006). Xanthan Gum. Retrieved from
https://www.foodchem.cn/products/Xanthan-Gum-
80mesh?campaignid=1599148988&DEV=c&PLC=&target=&keyword=xanthan%20
gum%20manufacturer&AD=304701291758&feeditem=&gclid=Cj0KCQiAgMPgBR
DDARIsAOh3uyJcbPy635xpNj6Scyz89W0UiRSi88rD567VtHTHf4X6n0TTvSqw_7
4aAvY6EALw_wcB

Kalogiannis, S., Gesthimani, L., Maria, L., Dimitros, A., & George, N. (2003). Optimization
of xanthan gum production by Xanthomonas campestris grown in molasses. Process
Biochemistry, 9, 249-256.

Lopes, B., Lessa, V., Silva, B., Filho, M., Schnitzler, E., & Lacerda, L. (2015). Xanthan gum:
properties, production conditions,. Journal of Food and Nutrition Research, 54(3), 185-
194.

Nussinovitch, A. (1997). Hydrocolloid Applications: Gum technology in the food and other
industries. London: Chapman & Hall.

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Palaniraj, A., & Jayaraman, V. (2011). Production, recovery and appilcations of Xanthan gum

by Xanthomonas campestris. Journal of Food Engineering, 1-12.

Rosalam, S., & England, R. (2006). Cell free xanthan gum production from unmodified
starches by xanthomonas campestris sp. Enzyme and Microbial Technology, 39, 197-
207.

Singha, T. K. (2012). Microbial Extracellular Polymeric Substances: Production, Isolation and.
Journal of Pharmacy, 2(2), 276-281.

Singhal, P. (15 September, 2011). Xanthan gum-Bioindustrial viewpoint and applications.
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