88
M. N. Abubacker and M. Prince
waste amounts for more than 60% of the total biomass (Kuhad et al. 1997). Forest
is the suitable-substratum where the micro and macro fungi not only live but also to
degrade the leaf litter fallen from the trees and supply most valuable nutrients back
to the forest soil. A large amount of plant waste (leaf litter) is being continuously
accumulated on the forest soil. A part of the waste gets into the soil and an intensive degradation process starts. Intensity of this decay process depends on different
environmental factors such as: species of plant, sort of soil, moisture, temperature
and microbial associations. In order to increase the efficiency of these metabolic
processes, the scientific society is making strong efforts in this area. Moreover, the
aim of the latest researches are oriented to intensify plant remnants decay and modify
metabolites enriching the soil by useful biologically active substances and finding
materials able to enrich forage and food by important biologically valuable additions
(Kelley 1992; Varnaite 2001; Abubacker and Prince 2013, 2015).
1.1 Forest Biomass
The composition of lignocellulose materials forms the wood wall structure. The
major component of lignocellulose material is cellulose, along with lignin and hemicellulose. Cellulose and hemicellulose are macromolecules formed from different
sugars; whereas lignin is an aromatic polymer synthesized from phenylpropanoid
precursors. The composition and percentages of these polymers vary from one plant
species to another. Moreover, the composition within a single plant varies with age,
stage of growth, and other conditions (Jeffries 1994; Krishna and Mohan 2017).
Hemicellulose is a complex carbohydrate polymer and makes up 25–30% of
total dry weight of wood. It is a polysaccharide with a lower molecular weight than
cellulose. It consists of D-xylose, D-mannose, D-galactose, D-glucose, L-arabinose,
4-O-methyl-glucuronic, D-galacturonic and D-glucuronic acids. Sugars are linked
together by β-1,4- and occasionally β-1,3-glycosidic bonds. The principal component
of hardwood hemicellulose is glucuronoxylan whereas glucomannan is predominant
in softwood. Structures of hemicelluloses are described in several reviews the main
difference with cellulose is that hemicellulose has branches with short lateral chains
consisting of different sugars. In contrast to cellulose, they are easily hydrolyzable
polymers. They do not form aggregates, even when they are co-crystallized with
cellulose chains (Jeffries 1994).
Lignin (along with cellulose) is the most abundant polymer in nature. It is present
in the cellular cell wall, conferring structural support, impermeability, and resistance
against microbial attack and oxidative stress. Structurally, lignin is an amorphous
heteropolymer, non-water soluble and optically inactive; it consists of phenylpropane
units joined together by different types of linkages (Jeffries 1994).
M. N. Abubacker and M. Prince
waste amounts for more than 60% of the total biomass (Kuhad et al. 1997). Forest
is the suitable-substratum where the micro and macro fungi not only live but also to
degrade the leaf litter fallen from the trees and supply most valuable nutrients back
to the forest soil. A large amount of plant waste (leaf litter) is being continuously
accumulated on the forest soil. A part of the waste gets into the soil and an intensive degradation process starts. Intensity of this decay process depends on different
environmental factors such as: species of plant, sort of soil, moisture, temperature
and microbial associations. In order to increase the efficiency of these metabolic
processes, the scientific society is making strong efforts in this area. Moreover, the
aim of the latest researches are oriented to intensify plant remnants decay and modify
metabolites enriching the soil by useful biologically active substances and finding
materials able to enrich forage and food by important biologically valuable additions
(Kelley 1992; Varnaite 2001; Abubacker and Prince 2013, 2015).
1.1 Forest Biomass
The composition of lignocellulose materials forms the wood wall structure. The
major component of lignocellulose material is cellulose, along with lignin and hemicellulose. Cellulose and hemicellulose are macromolecules formed from different
sugars; whereas lignin is an aromatic polymer synthesized from phenylpropanoid
precursors. The composition and percentages of these polymers vary from one plant
species to another. Moreover, the composition within a single plant varies with age,
stage of growth, and other conditions (Jeffries 1994; Krishna and Mohan 2017).
Hemicellulose is a complex carbohydrate polymer and makes up 25–30% of
total dry weight of wood. It is a polysaccharide with a lower molecular weight than
cellulose. It consists of D-xylose, D-mannose, D-galactose, D-glucose, L-arabinose,
4-O-methyl-glucuronic, D-galacturonic and D-glucuronic acids. Sugars are linked
together by β-1,4- and occasionally β-1,3-glycosidic bonds. The principal component
of hardwood hemicellulose is glucuronoxylan whereas glucomannan is predominant
in softwood. Structures of hemicelluloses are described in several reviews the main
difference with cellulose is that hemicellulose has branches with short lateral chains
consisting of different sugars. In contrast to cellulose, they are easily hydrolyzable
polymers. They do not form aggregates, even when they are co-crystallized with
cellulose chains (Jeffries 1994).
Lignin (along with cellulose) is the most abundant polymer in nature. It is present
in the cellular cell wall, conferring structural support, impermeability, and resistance
against microbial attack and oxidative stress. Structurally, lignin is an amorphous
heteropolymer, non-water soluble and optically inactive; it consists of phenylpropane
units joined together by different types of linkages (Jeffries 1994).