Environmental Engineering Reference
In-Depth Information
Biotechnological Applications of Hemicellulosic
Derived Sugars: State-of-the-Art
Anuj K. Chandel, Om V. Singh, and L.Venkateswar Rao
Abstract Hemicellulose is the second most abundant polysaccharide in nature,
after cellulose. As a substrate, it is readily available for the production of
value-added products with industrial significance, such as ethanol, xylitol, and
2, 3-butanediol. Hemicellulose is a heterogeneous carbohydrate polymer with a
xylose-linked backbone connecting to glucose, galactose, mannose, and sugar acids.
In general, it represents about 35% of lignocellulosic biomass. It is estimated that
the annual production of plant biomass in nature, of which over 90% is lignocellu-
lose, amounts to about 200
10 9 tons of the
primary biomass remains potentially accessible. Hemicellulose, which is generally
20-35% of lignocellulose amounts to nearly ~70
10 9 tons per year, where about 8-20
10 9 tons per year. Continuous
efforts by researchers in the last two decades have led the way for the successful
conversion of hemicellulose into fermentable constituents by developed candidate
pretreatment technologies and engineered hemicellulase enzymes. A major chal-
lenge is the isolation of microbes with the ability to ferment a broad range of
sugars and withstand fermentative inhibitors that are usually present in hemicel-
lulosic sugar syrup. This chapter aims to explore and review the potential sources of
hemicellulose and their degradation into fermentable sugars, as well as advocating
their conversion into value-added products like ethanol, xylitol, and 2, 3-butanediol.
Keywords Hemicellulose
2, 3-Butanediol
1 Introduction
Biomass in the form of cellulose, hemicellulose, and lignin provides a means of
collecting and storing solar energy, and hence represents an important energy and
material resource [1-3]. After cellulose, hemicellulose is the principal fraction of the
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