Xanthan Gum

XANTHAN GUM

Synonyms

Xynthan gum.

Biological Source

Xanthan is a microbial polysaccharide produced from Xanthomonas compestris.

Production

One of the latest techniques of biotechnology, that is, recombinant DNA technology has been duly exploited for the commercial production of xanthan gum.

First of all the genomic banks of Xanthomonas compestris 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 Xan-thomonas compestris. 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 Xanthomonas compestris shall afford an increased produc-tion of xanthan gum.

Interestingly, the commercial xanthan gums are avail-able with different genetically controlled composition, molecular weights and as their respective sodium, potassium or calcium salts.

Morphology

Chemical Constituents

Xanthan gum is composed of chiefly D-glucosyl, D-mannosyl and D-glucosyluronic 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

Xanthan is found to have very wide range of applications. It is widely used as a stabilizer and suspending agent in emulsion, paints, agricultural and herbicidal sprays. Applications are found in food, pharmaceutical and other industries. Specific applications depend upon the rheological behaviour of xanthan in solution. Synergistic effects are observed in food when xanthan is mixed with galactomannans such as guar gum or locust bean gum. It is used as a viscosity controller in abrasives and adhesives. It finds it valuable applications as gelling agent in explosives and flocculating agent in extraction.

Marketed Products

Xanthan is the only microbial gum that is currently produced on commercial scale by Kelco Inc., San Diego, United States, and by Rhone Poulene, S.A., Melle, France. It is marketed under the variety of trade names like Keltrol^©, Kelzan^© or Rhodogel^©.