Environmental Engineering Reference
In-Depth Information
Fig. 1 Mechanistic steps involved in hemicellulose bioconversion into ethanol, xylitol and
2, 3-butanediol
industry. However, several yeast species have the basic ability to carry out these
processes, i.e., Candida shehatae, Pichia stipitis, and Pachysolen tannophilus for
ethanol production; C. utilis , C. intermedia , and C. gulliermondii for xylitol pro-
duction; and Klebsiella oxytoca ATCC 8724, Bacillus subtilis (Ford strain), and
Aeromonas hydrophilia for 2, 3-butanediol production [4]. This chapter presents sig-
nificant advancements in hemicellulose biotechnology, with an emphasis on acidic
and enzymatic hydrolysis and the conversion of hemicellulose hydrolysates into
commercial products like ethanol, xylitol, and 2, 3-BD.
2 Background Research
To reduce the production of greenhouse gases and ensure sustainable global eco-
nomic development, it is important to increase the use of renewable biomass
resources [14]. There have been active movements accelerating the utilization of
lignocellulose-derived products such as bioethanol, xylitol, microbial enzymes, and
2, 3-BD into alternative source of bioenergy [4, 15, 16]. Ethanol has drawn the most
attention due to its rapid consumption and the global price fluctuations of crude
petroleum [15, 17].
Due to developments in industrial biotechnology, the carbohydrate fraction of the
cell wall can be converted into products of industrial significance. However, hemi-
cellulose has been explored less extensively than cellulose due to several factors.
The hemicelluloses in lignocellulosic materials are broken down into fermentable
sugars by either chemical or enzymatic hydrolysis [18]. The latter is a promising
method that breaks down hemicellulosic materials into fermentable sugars without
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