Page 93 - Refining Biomass Residues for Sustainable Energy and Bioproducts

68 Refining Biomass Residues for Sustainable Energy and Bioproducts

clusters may occur in this species. Even though a huge number of new bacterial
EPS are being reported over recent decades, very few of them have emerged as
industrially important biopolymers and thus extensive work on the regulation
mechanisms of the EPS production still needs to be studied on the genomic and
proteomic level to emphasize its potentiality at the global market.

3.5 Application aspects of microbial synthesized polymer

3.5.1 Applications of polyhydroxyalkanoate

PHAs are a group of naturally occurring bacterially synthesized biopolyesters. The
properties of PHA, such as size, shell core composition, and significant features
(biodegradable and biocompatible nature), replace nonbiodegradable petro-
leum mediated polymers in several areas, such as medicines, drug-delivery, agri-
culture, fiber industry, and horticulture (Da Silva et al., 2009). Bioplastics have
many diverse applications since their discovery in 1982. Initially, bioplastics were
only used for fabrication of various products, such as bottles, fibers, latex, and pro-
ducts, used in agriculture, packaging, and commercial applications but nowadays
they are employed for various medical applications, such as implants, sutures, neu-
ral and cardiovascular-tissue engineering urological stents, fixation of fractures, nar-
colepsy treatment, as drug-delivery vehicles, hypophyseal cells supporting, and
cell-microencapsulation. Also, they are used as precursors of molecules with anal-
gesic, chemopreventive, radiopotentioator, antihelminthic, antirheumatic, and anti-
tumoral properties (Luengo et al., 2003). Nowadays, research on the application of
spherical structure and bead nature of PHA molecule is also gaining interest (Grage
et al., 2009). It is reported that large molecular weight, spherical structure, and
surface-associated protein make PHA granules as ideal tools for the process of pro-
tein immobilization and purification (Grage et al., 2009). Grage et al. (2009)
reported the application of PHA beads in diagnostic, bioimaging procedures and
therapeutic areas by immobilizing protein (protein) at the surface of PHA granules.
In a study by Yao et al. (2008) a receptor-mediated drug-delivery system was devel-
oped in which PhaP was fused to cell-specific ligands hAGP (human acid glycopro-
tein) and hEGF (human growth factor). PHA granule application in targeted drug
delivery is possible due to its property of being a biocompatible polymer and as
biobead. In comparison to others, drug carrier system using PHA beads and gran-
ules is feasible and cost-effective (Grage et al., 2009).

3.5.2 Application of EPS
Microbially synthesized polysaccharides, such as EPS, have unique physical
and chemical properties (such as non-Newtonian behavior and high viscosity in
aqueous media) which make them functionally important as thickening, film-
forming, gelling, emulsifying and viscosifying, stabilizing, flocculating, and nano/
microstructure production activities (Table 3.5)(Freitas et al., 2011; Roca et al., 2015).