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.
Source: Pharmacognosy And Pharmacobiotechnology By Ashutosh Kar
Source: Pharmacognosy And Pharmacobiotechnology By Ashutosh Kar
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