ethanolgenic industrial strain for biofuel production. While on the other side,
advances in research technologies (that involves gene expression system, plasmid
vector, gene mutation, gene function, gene knockout, transposon system) help in
better genetic development of industrial biotechnology (Rogers et al. 2007).
Lignocellulosic ethanol production is restricted by low concentration of ethanol
which results in high distillation costs and one of its required conditions for ensuring
energy usage and economic balance of lignocellulosic ethanol is distillation
(Koppram et al. 2014; Sun et al. 2020).
6.2 Attractive Physical Characteristics of Zymomonas
mobilis for Biotechnology
Z. mobilis is a common microorganism that lives without oxygen. It is an
ethanologenic bacterium that has gram-negative cell wall. It has many useful
industrial features. For example, it is considered that Zymomonas mobilis is safe
(GRAS), that represent high tolerance efficiency of bioethanol more than 6% (v/v), it
can make bioethanol with variable range of pH (low pH, 3.5–7.5). Like an anaerobic
bacteria, the Zymomonas mobilis does not need to regulate aeration when fermentation process occurs, so lessens the production value (He et al. 2014; Jackson et al.
2007; Yang et al. 2016a, b).
A natural ethanologen is the optional anaerobic bacterium Zymomonas mobilis
and past studies have greatly defined its physiology in relation to commercial
processes such as the manufacture of biofuel (Wang et al. 2018). Only small
quantities of carbon substrates are integrated in Z. mobilis as biomass and this is
an enticing biocatalyst in refining systems (Wang et al. 2018; Kalnenieks et al.
2008).
When compared the EMP glycolysis mechanism with other species like
Escherichia coli and Saccharomyces cerevisiae just 1 mole of ATP resulted via
glucose of every ED pathway. Previous studies showed that the ED metabolic
pathway has lessen relation with heat and needs low enzymatic protein than the
EMP pathway that needs to hold equal flux (Lee and DeVries 2013). An active ED
pathway is combined with 2 alcohol dehydrogenases (Adh) and 1 pyruvate decarboxylase that make glycolysis mechanism for Zymomonas mobilis. It is noted that
the pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and EMP
pathway are not completed in Zymomonas mobilis. Because in this microorganism
most of the enzymes that are used in these pathways are not recognized (Table 6.1).
Z. mobilis breathing chain exhibits unique strength and cellular growth with a
suggested physiology to regulate ratio of low NADH/NAD
+ for active cellular
growth and glycolysis (Hayashi et al. 2015; Rutkis et al. 2014). In the presence of
oxygen, Zymomonas mobilis used the O 2 like electron receptor that terminates the
active respiratory chain which includes cytochrome b, NADH dehydrogenase type II
(Ndh), terminal oxidase, and coenzyme Q10 which are electron carriers other small
6 Engineering of Zymomonas mobilis for Enhanced Biofuel Production
157
advances in research technologies (that involves gene expression system, plasmid
vector, gene mutation, gene function, gene knockout, transposon system) help in
better genetic development of industrial biotechnology (Rogers et al. 2007).
Lignocellulosic ethanol production is restricted by low concentration of ethanol
which results in high distillation costs and one of its required conditions for ensuring
energy usage and economic balance of lignocellulosic ethanol is distillation
(Koppram et al. 2014; Sun et al. 2020).
6.2 Attractive Physical Characteristics of Zymomonas
mobilis for Biotechnology
Z. mobilis is a common microorganism that lives without oxygen. It is an
ethanologenic bacterium that has gram-negative cell wall. It has many useful
industrial features. For example, it is considered that Zymomonas mobilis is safe
(GRAS), that represent high tolerance efficiency of bioethanol more than 6% (v/v), it
can make bioethanol with variable range of pH (low pH, 3.5–7.5). Like an anaerobic
bacteria, the Zymomonas mobilis does not need to regulate aeration when fermentation process occurs, so lessens the production value (He et al. 2014; Jackson et al.
2007; Yang et al. 2016a, b).
A natural ethanologen is the optional anaerobic bacterium Zymomonas mobilis
and past studies have greatly defined its physiology in relation to commercial
processes such as the manufacture of biofuel (Wang et al. 2018). Only small
quantities of carbon substrates are integrated in Z. mobilis as biomass and this is
an enticing biocatalyst in refining systems (Wang et al. 2018; Kalnenieks et al.
2008).
When compared the EMP glycolysis mechanism with other species like
Escherichia coli and Saccharomyces cerevisiae just 1 mole of ATP resulted via
glucose of every ED pathway. Previous studies showed that the ED metabolic
pathway has lessen relation with heat and needs low enzymatic protein than the
EMP pathway that needs to hold equal flux (Lee and DeVries 2013). An active ED
pathway is combined with 2 alcohol dehydrogenases (Adh) and 1 pyruvate decarboxylase that make glycolysis mechanism for Zymomonas mobilis. It is noted that
the pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and EMP
pathway are not completed in Zymomonas mobilis. Because in this microorganism
most of the enzymes that are used in these pathways are not recognized (Table 6.1).
Z. mobilis breathing chain exhibits unique strength and cellular growth with a
suggested physiology to regulate ratio of low NADH/NAD
+ for active cellular
growth and glycolysis (Hayashi et al. 2015; Rutkis et al. 2014). In the presence of
oxygen, Zymomonas mobilis used the O 2 like electron receptor that terminates the
active respiratory chain which includes cytochrome b, NADH dehydrogenase type II
(Ndh), terminal oxidase, and coenzyme Q10 which are electron carriers other small
6 Engineering of Zymomonas mobilis for Enhanced Biofuel Production
157