Exopolysaccharides bacterial

The presence of organic acid substituents in exopolysaccharides increases the lipophilidty of the molecule. In addition, for some exopolysaccharides with relatively high organic acid contents, their interaction with cations and with other polysaccharides may be influenced. Several amino adds have also been found in bacterial exopolysaccharides, including serine and L-glutamic add (Figure 7.1). 

Savvaidis I, Hughes M, Poole R (1992) Differential pulse polarography a method of directly measuring uptake of metal ions by live bacteria without separation of biomass and medium. FEMS Microbiol Lett 92 181-186 Savvaidis I, Hughes MN, Poole RK (2003) Copper biosorption by Pseudomonas cepacia and other strains. World J Microbiol Biotechnol 19 117-121 Scott JA, Palmer SJ (1988) Cadmium biosorption by bacterial exopolysaccharide. Biotechnol Lett 10 21-24... 

Scott, J. A. Palmer, S.J. (1988). Cadmium bio-sorption by bacterial exopolysaccharide. Biotechnology Letters, 10, 21-4. 

It therefore seems possible that the biosynthesis of plant gums and mucilages follows a mechanism similar to that of bacterial exopolysaccharides. Experimental evidence should be obtained for plant systems in order to test this hypothesis. 

Finally, details of the synthesis of heteropolysaccharides in plants are as yet completely unknown. The structural similarities among some plant gums and such bacterial exopolysaccharides as xanthan gum suggest that similar mechanisms may be operative in bacteria and in plants. Lipid intermediates could be suggested as potential glycosyl donors in the formation of plant gums and mucilages. 

Bacterial exopolysaccharides (extracellular polysaccharides) include those that are made from sucrose, viz., dextrans and fructans. Dextrans are branched a-glucans containing (1 3) and/or (1 6) and occasionally (1 2) linkages. Fructans contain -D-fructofuranosyl units linked (2 6) or (2 1). 

Stirm S (1994) Examination of the repeating units of bacterial exopolysaccharides. In BeMiller IN, Manners DJ, Sturgeon RJ (eds) Methods in carbohydrate chemistry, vol X. Wiley, London, p 143... 

Fructose occurs rarely in the bacterial polysaccharide. It has been found in the LPS of several Vibrio species [108] and in the K4 [109] and Kll [110] capsular antigens of Escherichia coli. In all cases, fructose appears as a terminal residue. In several plant species, fructans consisting of p-D-fructofuranosyl units are present as important storage polymers. The structure of the polysaccharide isolated from B. caryophylli is different from those of the above polysaccharides however, as levan can be isolated as bacterial exopolysaccharides, this polysaccharide may be a side-product of levan biosynthesis. 

Guezennec, J. 2002. Deep-sea hydrothermal vents A new source of innovative bacterial exopolysaccharides of biotechnological interest J. Ind. Microbiol. Biotechnol. 29, 204-208. 

Sutherland, I.W. (1977). Bacterial Exopolysaccharides — Their Nature and Production in Surface Carbohydrates of the Prokaryotic Cell (Sutherland, I.W. ed.). Academic Press, London, New York, San Francisco, pp. 27-96. 

Neiss and Cheng have studied the microstructure of alginates and related it to the action of enzymes (69). Baianu and Ozu have examined the gelling mechanism of konjac gum and its interactions with proteins (63). Other studies include bacterial exopolysaccharides (86) and oligosaccharides (83,87),... 

Kumar AS, Mody K, Jha B QXXfl) Bacterial exopolysaccharides — a perception. J Basic Microbiol... 

Another complex polysaccharide which has been modified to enhance its properties is xanthan gum. Xanthan is a naturally produced bacterial exopolysaccharide of the etaxsXanthomonas. While many species of the genus will produce copious amounts of the polysaccharide, the model system for research and production is Xanthomonas campestris. Production is by bacterial fermentation using a media composed of 2.5 to 3% D-glucose, 0.4% dried distillers solubles, and simple salts (82). Within 96 hours 50% of the glucose is converted to xanthan. The cells are removed by centrifugation leaving the polysaccharide in solution. It is then precipitated by the addition of 50% (w/w) alcohol, often methanol or 2-propanol. The precipitate is dried and milled for commercial sale. 

The microbial EPSs are a class of high-value polymers that have many industrial applications. Research in this area has led to the production of several microbial polysaccharides on an industrial scale like xanthan, dextran, alginate, geUan, curdlan. Xanthan and gellan are commercially most appreciated on the global market for hydrocolloids with xanthan gum being the only significant bacterial exopolysaccharide, which accounted for 6% of the total market value. ... 

Kumar AS, Mody K,Jha B. Bacterial exopolysaccharides - a perception.J Basic Miaohiol 2007 47 103-17. 

Iyer A, Mody K, Jha B. Emukifying properties of a marine bacterial exopolysaccharide. Enzyme Microb Technol 2006 38 220-2. 

Sutherland IW. Bacterial exopolysaccharides. In Kamerling JP, editor. Comprehensive glycoscience. Amsterdam Elsevier 2007. 

Freitas F, Alves VD, Reis MA. Advances in bacterial exopolysaccharides from production to biotechnological applications. Trends Biotechnol 2011 29 388-98. 

Poll A, Anzekno G, Nicolaus B. Bacterial exopolysaccharides from extreme marine habitats production, characterization and biological activities. Rev Mar Drugs 2010 8 1779-802. 

P. Zanchetta, M. Lagarde, and J. Gu6zennec, A new bone-healing material A623 hyaluronic acid-like bacterial exopolysaccharide, Calcif. Tissue Int., 72 (2), 74-79,2003. 

Henao, L., and Mazeau, K. 2008. The molecular basis of the adsorption of bacterial exopolysaccharides on montmoriUonite mineral surface. Mol. Simul. 34 1029. 

Much of the degraded plant polysaccharide is converted into bacterial biomass. Radiolabelled glucose, dextran and plant tissues have been added to soils to determine the fate of plant polysaccharides. Appreciable amounts of radiolabel become localised in bacterial exopolysaccharides. 

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