Xanthan campestris

Xanthan, although a gum, is derived from the pure culture fermentation of an organism, TCanthomonas campestris. The organism is filtered from the growth medium and the gum recovered by alcohoHc precipitation, followed by drying. It is composed primarily of D-glucose and D-mannose units. 

Xanthan Gum. As a result of a project to transform agriculturally derived products into industrially usefiil products by microbial action, the Northern Regional Research Laboratories of the USDA showed that the bacterium TCanthomonas campestris - noduces a polysaccharide with industrially usefiil properties (77). Extensive research was carried out on this interesting polysaccharide in several industrial laboratories during the eady 1960s, culminating in commercial production in 1964. 

Xanthan gum [11138-66-2] is an anionic heteropolysaccharide produced by several species of bacteria in the genus Aanthomonas A. campestris NRRL B-1459 produces the biopolymer with the most desirable physical properties and is used for commercial production of xanthan gum (see Gums). This strain was identified in the 1950s as part of a program to develop microbial polysaccharides derived from fermentations utilizing com sugar (333,334). The primary... 

From a commercial point of view, xanthan gum is the most important microbial exopolysaccharide currently being manufactured. Therefore, we shall consider the fermentation of this product by Xanthomonas campestris in some detail. 

Figure 7.5 Production of xanthan gum in batch culture using X. campestris. Bacterial dry weight ( ) xanthan gum ( ) residual glucose ( ) residual glutamate (A). Adapted from Microbial exopolysaccharide, Yenton etai pp 217-261. In biomaterials Novel Materials from Biological Sources, D Byrom (Ed), MacMillan Academic Professional Ltd, 1991.

Figure 7.11 Restriction map of Xanthomonas campestris xanthan gene cluster. Adapted from R W Vanderslice at at. Genetic engineering of polysaccharide structure In Xanthomonas campestris. In Biomedical and Biotechnological Advances In Industrial Polysaccharides, 1989, Gordon and Breach N Y.

Xanthan gum is a slimy gel produced by the bacterium Xan-thomonas campestris, which causes black rot on cruciferous vegetables, such as cauliflower and broccoli. The slime protects the bacterium from viruses and prevents it from drying out. 

Fig. 35.—Circular Dichroism of the Xanthan from Xanthomonas campestris at Various Temperatures. (Redrawn from Ref. 81.)...

Xanthan Gum. Xanthan gum is produced by the bacterium Xanthomonas campestris. Commercial productions started in 1964. Xanthans are water-soluble polysaccharide polymers with the following repeating units [502], as given in Table 17-5 and Figure 17-6. 

Xanthan (Figure 11) is a commercially important polysaccharide produced by the bacterium Xanthomonas campestris.187 188 The xanthan backbone consists of a P(l-4)-linked D-glucopyranose chain with a trisaccharide side chain attached at C3 to alternate glucose residues. These side chains consist of an acetylated mannose residue, a glucuronic acid residue, and a pyruvate ketal linked to a terminal mannose residue. The acetate and pyruvate content depend on the fermentation and isolation conditions used by the supplier. 

Norton, I. T., Goodall, D. M., Morris, E. R., and Rees, D. A. Kinetic evidence for intramolecular conformational ordering of the extracellular polysaccharide (xanthan) from Xanthomonas campestris,. Chem. Soc. Chem. Comm., 545,1980. 

The oil price rises in the 1970s stimulated interest in Enhanced Oil Recovery (EOR), and fairly rapidly the biopolymer xanthan, the extracellular polysaccharide from the bacterium Xanthomonas campestris. an organism which normally resides on cabbage leaves, was identified as a leading contender as a viscosifier for polymer enhanced water flooding. 

Lactose can also be used as a substrate for Xanthomonas campestris in the production of xanthan gum (Figure 2.28) which has several food and industrial applications. 

Xanthan is the extracellular (exocellular) polysaccharide produced by Xanthomonas campestris. As with other microbial polysaccharides, the characteristics (polymer structure, molecular weight, solution properties) of xanthan preparations are constant and reproducible when a particular strain of the organism is grown under specified conditions, as is done commercially. The characteristics vary, however, with variations in the strain of the organism, the sources of nitrogen and carbon, degree of medium oxygenation, temperature, pH, and concentrations of various mineral elements. 

Production. Xanthan gum is produced by the microorganism X. campestris, originally isolated from the mtabaga plant. The gum is produced commercially by culturing X. campestris purely under aerobic conditions in a medium containing commercial glucose, a suitable nitrogen source, dipotassium phosphate, and appropriate essential elements. When the fermentation is complete, the gum is recovered from the fermentation broth by precipitation with isopropyl alcohol, and dried, milled, tested, and packed. 

Bacteria form and secrete a variety of heteropolysaccharides, several of which are of commercial value because of their useful gelling properties. Xanthan gum (formed by Xanthomonas campestris) has the basic cellulose structure but every second glucose residue carries an a-l,3-linked trisaccharide consisting of 6-0-acetylmannose, glucuronic acid, and mannose in the following repeating unit 131132... 

Xanthan is an extracellular polysaccharide produced by Xanthomonas campestris and related species. The structure of xanthan was determined chemically42,43 as a /3-(l - 4)-linked D-glucan to which are attached trisaccharide side-chains on each second D-glucosyl residue, as depicted in 1Z. 

Xanthan gum, dextran Xanthomonas campestris, Leuconostoc mesenteroides Food, pharmaceutical, textile industries, useful for thickening, stiffening and setting properties... 

Xanthan Xanthomonas campestris Highly viscous and pseudoplastic gels with galactomannes resistant to acid, alkali and biodegradation oil-well drilling, food industry... 

Xanthan Gum occurs as a cream colored powder. It is a high-molecular-weight polysaccharide gum produced by a pure-culture fermentation of a carbohydrate with Xanthomonas campestris, purified by recovery with isopropyl alcohol, dried, and milled. It contains D-glucose and D-mannose as the dominant hexose units, along with D-glucuronic acid and pyruvic acid, and it is prepared as the sodium, potassium, or calcium salt. It is readily soluble in hot or cold water, but it is insoluble in alcohol. Its solutions are neutral. 

Xanthan gum Thickener exhibits synergy with locust bean gum Polysaccharide Aerobic fermentation of Xanthomonas campestris... 

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