Page 99 - Refining Biomass Residues for Sustainable Energy and Bioproducts

72 Refining Biomass Residues for Sustainable Energy and Bioproducts

producing starter cultures. EPS are a suitable source of few monosaccharides (such
as L-fucose, L-rhamnose, L-altrose, D-mannose) as other sources (such as chemical
synthesis and extraction from plant) of monosaccharide are laborious and expen-
sive. Few of the bacterial strains have been reported for the production of EPS with
a significant source of monosaccharide (e.g., EPS named as Clavan, rich in
D-fucose, is obtained from Clavibacter species and a bacterial strain Klebsiella
pneumonia synthesizes L-fucose-rich EPS) (Kumar et al., 2007). A new reported
microbial product named poly-D-GlcA has similar properties as alginate. This poly-
mer can form a thermostable gel in the presence of calcium ion and can also form a
thermo-reversible gel in the presence of monovalent ions at higher concentration
(Kumar et al., 2007).

3.5.2.1.2 Other industry
Owing to a biodegradable nature, EPS have been commercialized and used as
surfactants and emulsifiers, for example, Emulsan an EPS obtained from
Acinetobacter calcoaceticus RAG-1 (Kumar et al., 2007). Welan gum is used in
cement production as it reduces the fluid loss of cement suspension (Roca et al.,
2015). Xanthan gum is commercially employed due to its high viscosity enhancing
ability at low concentrations in solution, strong pseudo-plasticity, stability over a
wide range of pH, temperature, and ionic strength. Due to these properties, xanthan
gum is used in the process of drilling fluids for oil recovery (Freitas et al., 2011;
Patel and Prajapat, 2013). A strain Enterobacter cloacae synthesized an exopoly-
saccharide having good viscosity even at high temperature and therefore it was
found suitable for oil recovery using microbial processes (Kumar et al., 2007).
Rhamsun gum is a nongel forming polysaccharide that forms highly

thermostable viscous solution at high temperature (above 100 C) and has industrial,
cosmetic, pharmaceutical, and medicinal applications (Roca et al., 2015). FucoPol,
another EPS with fucose sugar, has various functional properties, such as thicken-
ing, film-forming, emulsion stabilizing, and flocculating, and therefore used in
waste water treatment as biodegradable flocculants, in packaging as biodegradable
film and oil drilling fluids (Roca et al., 2015). EPS GalactoPol (containing galac-
tose) synthesized by Pseudomonas oleovorans has great biotechnological applica-
tions. It is reported that EPS, such as gellan, fucoPol, and galactoPol, have ability
to make cohesive polymer matrix used for film formation due to their physical and
chemical intermolecular interactions (Freitas et al., 2011).

3.5.2.2 Biomedical application

Exopolysaccharides, such as xanthan, sulfated dextran, and sulfated curdlan, have
medical applications as an antiviral and anticancer agent due to their inherent bio-
logical activity and ability to form polymeric matrices (Freitas et al., 2011).
Exopolysaccharides produced by marine bacteria Vibrio and Pseudomonas have
been studied for antitumor, antiviral, and immunostimulant activities (Kumar et al.,
2007). Gellan gum is used for tissue engineering (such as for cartilage