Page 98 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Microbial-derived natural bioproducts for a sustainable environment 71

Extremophiles produce EPS that show a biotechnological advantage of short fer-
mentation process while psychrophiles form easy and stable emulsions of EPS. This
shows the potential of EPS isolated from extremophiles in most of the biotechno-
logical applications, such as pharmaceutical industries, immunomodulatory and
antiviral effects, food-processing industries as gelling and thickening agent, as bio-
surfactants and detoxification of petrochemical-contaminated sites (Poli et al.,
2010).

3.5.2.1 Industrial application

Industrial applications of exopolysaccharides utilize its properties as a hydrophobic
molecule, ion exchange resin, bio-adsorbent, bioflocculant, and encapsulating
material.

3.5.2.1.1 Food industry
In the food industry, application of EPS utilizes its property as a stabilizing, emulsi-
fying, and viscosifying agent. Microbial production of EPS is a potential alternative
to artificial additives because of their consumer-friendly properties, such as low
level of fat and sugar, low level of food additives, and their cost factors (Poli et al.,
2011). Lactic acid bacteria (LAB) have synthesized an EPS known as dextran
which is the first industrial polysaccharide discovered in 1880. It was used for
thickening and gelation of syrups (Patel and Prajapat, 2013). Now dextran can be
used in various areas, such as in confectionary for moisture retention and improving
viscosity, as gelling agent in gum and jelly, as blood plasma extenders, and as a
basic component of chromatographic stationary phase. EPS named xanthan gum
obtained from plant-pathogen, X. campestris is the second microbially synthesized
EPS and is used as a thickening agent in the food industry, for example, dairy pro-
ducts, bakery products, and syrups (Patel and Prajapat, 2013). An EPS, Gelrite is a
new gelling polysaccharide with good thermal stability produced by bacterial strain
Pseudomonas species, forms clear, firm, and brittle gel after deacetylation with
mild alkali (Kumar et al., 2007). Gellan gum, a linear anionic EPS, contains glyc-
eryl and acetyl groups. High acyl gellan makes soft, elastic, nonbrittle, and opaque
gels, whereas low acyl gellan makes hard, nonelastic, brittle, and transparent gels.
It is used as an additive which behaves like texturizing, gelling, stabilizing, sus-
pending, film-forming, and structuring agent altogether. Welan gum has a good rhe-
ological property and can be used in food products, such as jellies, dairy products,
and beverages (Roca et al., 2015). In the food industry, EPS produced by LAB are
GRAS (generally recognized as safe) for usage as food polymers. EPS produced by
LAB have influencing properties, such as syneresis, sensory, and high viscosity,
which retain flavor and add prolong life to fermented food (Zhou et al., 2018).
Their EPS are used mostly in the dairy industry as the in situ produced EPS by
LAB increase the textures and rheological properties of fermented dairy products
which are considered healthy because of immunostimulatory, cholesterol-lowering
activity, or antitumoral property (Poli et al., 2011). A study by Amatayakul et al.
(2005) has shown a better water-holding capacity of yogurt made with EPS