pretreatment, choosing appropriate enzymes and strains, choosing non-catalytic
proteins, the chemicals, etc. (Adsul et al. 2020). There is a wide variety of biomasses
(sugar cane, corn cob, wheat straw, banane waste, microalgae, etc.), and each of the
biomasses has different heterogeneity (depending on the compounds they contain
and the amount of these compounds) (Kenney et al. 2013; Williams et al. 2016).
Moreover, depending on the type of the applied pretreatment (with alkali/acid/
steam, etc.), the chemical composition and structure of the biomass vary (Li et al.
2014; Satlewal et al. 2018). Again, choosing the appropriate strain(s) is also important for the supply of the enzymes (appropriate for the chemical composition/
structure of the biomass) which will function in the hydrolysis of the biomass.
Natural microbial strains can produce sufficient enzymes for their vital functions,
but may not meet demands on industrial scales (Adsul et al. 2020). To reach high
levels of expression (increasing the enzyme production efficiency), strain improved
through genetic modifications (e.g., cloning and mutation) is required (Juturu and
Wu 2014; Singh et al. 2017; Singhania et al. 2017).
LPMOs (see Sect. 9.4.5) have become the focus of interest in the degradation of
the pretreated lignocellulosic biomass (Eibinger et al. 2014; Couturier et al. 2018).
It has been pointed out that the LPMO/AA9 helps the biomass to liquify rapidly
and thus increases the accessibility of the other enzymes to the biomass. Furthermore, it has been stated that adding optimum AA9 to the cellulase preparate
decreases the general protein/cellulase load by 5–6 times (Sun et al. 2015) and the
hydrolysis of the biomass which holds more lignin in its structure after the
pretreatment is conducted more effectively with the synergic effect of the cellulase
preparate and AA9 (Hu et al. 2014).
It has been reported that some non-hydrolytic proteins affect the decomposition
process of the cellulose, which is characterized by the dispersion of the microfibrils
and the swelling of the macrofibrils. These effects are a decrease in the crystallinity
of the cellulose, an increase both in the cellulose surface area and in the accessibility
to cellulose (Arantes and Saddler 2010; Chen et al. 2010; Adsul et al. 2020). For this
reason, these proteins function as the factors that increase the cellulase activity. The
functions of these proteins (plant-like expansin, swollenin, and CBM (see Sect.
9.3.2)) can be explained with a couple of examples.
As demonstrated in the study of Kim et al., expansin (B5EXLX1), isolated from
Bacillus subtilis and expressed heterologously in Escherichia coli, increased the
synergistic effect by 240% and the overall enzymatic activity 5.7 times when used
with cellulases (Kim et al. 2009).
Moreover, it has been stated that, when fungal (Orpinomyces sp. strain CIA)
swollenin expressed in high amounts is included in a cellulolytic cocktail, depending
on the pretreatment type, it provides up to 7% improvement in the hydrolysis of the
corn stover (pretreated with liquid, alkali, acid and ionic, respectively) (Morrison
et al. 2016). Besides these proteins, a small heat-shock protein (cbHsp 18) obtained
from bacteria has also been found to contribute to the hydrolysis of bioenergy
feedstock by increasing the thermal stability of the glycoside hydrolases (Su et al.
2012).
9 Microbial and Bioinformatics Approach in Biofuel Production
283
proteins, the chemicals, etc. (Adsul et al. 2020). There is a wide variety of biomasses
(sugar cane, corn cob, wheat straw, banane waste, microalgae, etc.), and each of the
biomasses has different heterogeneity (depending on the compounds they contain
and the amount of these compounds) (Kenney et al. 2013; Williams et al. 2016).
Moreover, depending on the type of the applied pretreatment (with alkali/acid/
steam, etc.), the chemical composition and structure of the biomass vary (Li et al.
2014; Satlewal et al. 2018). Again, choosing the appropriate strain(s) is also important for the supply of the enzymes (appropriate for the chemical composition/
structure of the biomass) which will function in the hydrolysis of the biomass.
Natural microbial strains can produce sufficient enzymes for their vital functions,
but may not meet demands on industrial scales (Adsul et al. 2020). To reach high
levels of expression (increasing the enzyme production efficiency), strain improved
through genetic modifications (e.g., cloning and mutation) is required (Juturu and
Wu 2014; Singh et al. 2017; Singhania et al. 2017).
LPMOs (see Sect. 9.4.5) have become the focus of interest in the degradation of
the pretreated lignocellulosic biomass (Eibinger et al. 2014; Couturier et al. 2018).
It has been pointed out that the LPMO/AA9 helps the biomass to liquify rapidly
and thus increases the accessibility of the other enzymes to the biomass. Furthermore, it has been stated that adding optimum AA9 to the cellulase preparate
decreases the general protein/cellulase load by 5–6 times (Sun et al. 2015) and the
hydrolysis of the biomass which holds more lignin in its structure after the
pretreatment is conducted more effectively with the synergic effect of the cellulase
preparate and AA9 (Hu et al. 2014).
It has been reported that some non-hydrolytic proteins affect the decomposition
process of the cellulose, which is characterized by the dispersion of the microfibrils
and the swelling of the macrofibrils. These effects are a decrease in the crystallinity
of the cellulose, an increase both in the cellulose surface area and in the accessibility
to cellulose (Arantes and Saddler 2010; Chen et al. 2010; Adsul et al. 2020). For this
reason, these proteins function as the factors that increase the cellulase activity. The
functions of these proteins (plant-like expansin, swollenin, and CBM (see Sect.
9.3.2)) can be explained with a couple of examples.
As demonstrated in the study of Kim et al., expansin (B5EXLX1), isolated from
Bacillus subtilis and expressed heterologously in Escherichia coli, increased the
synergistic effect by 240% and the overall enzymatic activity 5.7 times when used
with cellulases (Kim et al. 2009).
Moreover, it has been stated that, when fungal (Orpinomyces sp. strain CIA)
swollenin expressed in high amounts is included in a cellulolytic cocktail, depending
on the pretreatment type, it provides up to 7% improvement in the hydrolysis of the
corn stover (pretreated with liquid, alkali, acid and ionic, respectively) (Morrison
et al. 2016). Besides these proteins, a small heat-shock protein (cbHsp 18) obtained
from bacteria has also been found to contribute to the hydrolysis of bioenergy
feedstock by increasing the thermal stability of the glycoside hydrolases (Su et al.
2012).
9 Microbial and Bioinformatics Approach in Biofuel Production
283