2.2.4.1 Xanthan Gum
Synonyms Polysaccharide B-1459; Keltrol F; Kelzan.
Biological Source The Polysaccharide Gum is produced by the bacterium Xanthomonas campestris on certain suitable carbohydrates.
Preparation One of the latest techniques of ‘biotechnology’ i.e., ‘recombinant DNA technology’ has been duly exploited for the commercial production of xanthan gum.
Methodology: First of all the genomic banks of Xanthomonas campestris are meticulously made in Escherichia coli by strategically mobilizing the broad-host-range cosmids being used as the vectors. Subsequently, the conjugal transfer of the genes take place from E. coli into the nonmucoid X. campestris. Consequently, the wild type genes are duly separated by virtue of their unique ability to restore mucoid phenotype. As a result, a few of the cloned plasmids incorporated in the wild type strains of X. campestris shall afford an increased production xanthan gum.
Interestingly, the commercial xanthan gums are available with different genetically controlled composition, molecular weights and as their respective sodium, potassium or calcium salts.
Description It is a cream coloured, odourless and free flowing powder. It dissolves swiftly in water on shaking and yields a highly viscous solution at relatively low concentrations. The aqueous solutions are extremely pseudoplastic in character. It gives rise to a strong film on evaporation of its aqueous solutions. It is fairly stable and resistent to thermal degradation. The viscosity is independent of temperature between 10 to 70oC. It is fairly compatible with a variety of salts.
Chemical Constituents Xanthan gum is composed of chiefly D-glucosyl, D-mannosyl and Dglucosyluronic acid residues along with variant quantum of O-acetyl and pyruvic acid acetal. The primary structure essentially comprises of a cellulose backbone with trisaccharide side chains and the repeating moiety being a pentasaccharide.
Uses
1. Its potential in chemically enhanced oil recovery is well known.
2. The inherent pseudoplastic property of its aqueous solutions rendered both toothpastes and ointments in enabling them to hold their shape and also to spread readily.
3. It is extensively employed in pharmaceuticals due to its superb suspending and emulsifying characteristic features.
