chains of different hexose and pentose sugars (such as
xylose, mannose, galactose, rhamnose, and arabinose) and
uronic acids (Lin et al. 2015). Glucuronoxylan and glucomannan are the principal components of hardwood and
softwood hemicellulose, respectively (Pérez et al. 2002).
2.3 Lignin
Lignin is a complex, branched phenolic polymer containing
three phenylpropanolic monomers linked by carbon-carbon
and aryl-ether bonds (Lu et al. 2017; Upton and Kasko
2016). Lignin accounts for 30% of total organic carbon
found on Earth (Upton and Kasko 2016). It is an aromatic
natural polymer found in all terrestrial and some of the
aquatic plants (Guragain et al. 2015). It acts as a potentially
renewable resource for energy and aromatic chemical production. The lignin provides structural support, impermeability, transport water and nutrients, and protection against
chemical and pathogen attack (Polo et al. 2020; Bonawitz
and Chapple 2010).
3 Bioconversion of Lignocellulosic Biomass
Each year several tons of lignocellulosic wastes are produced
from different sources including forestry and agricultural
biomass, paper and food industries, and municipal solid waste
(Limayem and Ricke 2012; Dashtban et al. 2009). Even
today, these biomasses are considered as waste materials in
developing countries which are creating several environmental issues (Chen et al. 2017; Worden et al. 2017). However, recent data suggested that lignocellulosic biomasses can
be successfully converted into biofuels (Putro et al. 2016).
The global bioethanol production has dramatically increased
since 2000 and reached up to 72.06 Billion Gallons per year in
2017 (EIA 2020) (Fig. 2). More than 84% of the global
ethanol fuel production (22.86 out of 27.06 Billions of
Fig. 1 Diagrammatic representation of the lignocellulosic biomass and the role of pretreatment in the bioconversion
Fig. 2 Biofuel production by countries from 2000 to 2017 (Data
source EIA (2020))
Bioconversion of Hemicelluloses into Hydrogen
269
xylose, mannose, galactose, rhamnose, and arabinose) and
uronic acids (Lin et al. 2015). Glucuronoxylan and glucomannan are the principal components of hardwood and
softwood hemicellulose, respectively (Pérez et al. 2002).
2.3 Lignin
Lignin is a complex, branched phenolic polymer containing
three phenylpropanolic monomers linked by carbon-carbon
and aryl-ether bonds (Lu et al. 2017; Upton and Kasko
2016). Lignin accounts for 30% of total organic carbon
found on Earth (Upton and Kasko 2016). It is an aromatic
natural polymer found in all terrestrial and some of the
aquatic plants (Guragain et al. 2015). It acts as a potentially
renewable resource for energy and aromatic chemical production. The lignin provides structural support, impermeability, transport water and nutrients, and protection against
chemical and pathogen attack (Polo et al. 2020; Bonawitz
and Chapple 2010).
3 Bioconversion of Lignocellulosic Biomass
Each year several tons of lignocellulosic wastes are produced
from different sources including forestry and agricultural
biomass, paper and food industries, and municipal solid waste
(Limayem and Ricke 2012; Dashtban et al. 2009). Even
today, these biomasses are considered as waste materials in
developing countries which are creating several environmental issues (Chen et al. 2017; Worden et al. 2017). However, recent data suggested that lignocellulosic biomasses can
be successfully converted into biofuels (Putro et al. 2016).
The global bioethanol production has dramatically increased
since 2000 and reached up to 72.06 Billion Gallons per year in
2017 (EIA 2020) (Fig. 2). More than 84% of the global
ethanol fuel production (22.86 out of 27.06 Billions of
Fig. 1 Diagrammatic representation of the lignocellulosic biomass and the role of pretreatment in the bioconversion
Fig. 2 Biofuel production by countries from 2000 to 2017 (Data
source EIA (2020))
Bioconversion of Hemicelluloses into Hydrogen
269