44
2 High-Efficient Anaerobic Fermentation Technology of Organic …
kinase from Methanosarcina became the most significant enzyme needed for acetylCoA to produce acetic acid and it linked the combined hydrogen process and methane
production. Widely existing in these bacterial communities, acetyl-CoA synthetase
is affiliated only to archaea in Methanosaeta during SHPT, being involved in acetate
metabolism. Merely being identified in Stage 2, the tetrahydromethanopterin Smethyltransferase was affiliated to Methanosarcina, transforming one-carbon groups
including participates and methyltransferases in biosynthesis of folate. Acetyl-CoA
and phosphate serve as the substrates of the phosphate acetyltransferase enzyme,
while the two products of the enzyme include acetyl phosphate and CoA.
As illustrated by grey circles in Fig. 2.21, CO 2 reduction is another primary pathway to the methanogenesis in SHTP. The evidences for the pathway
included: (i) the major subunits of formate dehydrogenase; (ii) glycine hydroxymethyltransferase; (iii) methylenetetrahydromethanopterin dehydrogenase; (iv)
5,10-methylenetetrahydromethanopterin reductase; (v) subunits alpha and beta
of coenzyme F 420 hydrogenase; and (vi) alpha subunit of pyruvate ferredoxin
oxidoreductase. The major subunits of formate dehydrogenase exert catalyzation effects on the dehydrogenation of formic acid and through the CO 2 reduction pathway, they function as the electron donor for production of methane.
Glycine hydroxymethyltransferase appeared in Leclercia and Acinetobacter bacteria in Stages II and III. Methylenetetrahydromethanopterin dehydrogenase exerted
effects on the CH–NH group of donors with other acceptors and belongs to
Methanosarcina in all of the three stages. The enzyme has the two substrates
of 5,10-methylenetetrahydromethanopterin and coenzyme F 420 , whereas 5,10methenyltetrahydromethanopterin and reduced coenzyme F 420 are the two products.
The interesting thing is that 5,10-methylenetetrahydromethanopterin reductase and
alpha subunit of pyruvate ferredoxin oxidoreductase were merely obtained in Stage II
and belonged to Methanothermobacter in archaea. The identified proteins sub-units
alpha and beta of coenzyme F 420 hydrogenase were separately affiliated to Methanothermobacter and Methanococcus, which functioned as a deazaflavin analogue, and
used formic acid and hydrogen as electron donors to generate methane by reducing
CO 2 .
According to the blue circles in Fig. 2.21, a primary methylotrophic pathway was revealed by the identified proteins of methylamine–corrinoid protein
Co-methyltransferase assigned to Methanosarcina. This protein produces methane
through reduction of methyl with hydrogen in methyl compounds or via the dismutation of methyl compounds. Moreover, three proteins of subunit of methylCo M reductase were identified and found belonging to Methanothermobacter,
Methanosarcina, and Methanotorris in phylum Euryarchaeota during SHPT. It is
the terminal methyl carrier and the critical enzyme for all three pathways of methane
production (Jia et al. 2017b).
2 High-Efficient Anaerobic Fermentation Technology of Organic …
kinase from Methanosarcina became the most significant enzyme needed for acetylCoA to produce acetic acid and it linked the combined hydrogen process and methane
production. Widely existing in these bacterial communities, acetyl-CoA synthetase
is affiliated only to archaea in Methanosaeta during SHPT, being involved in acetate
metabolism. Merely being identified in Stage 2, the tetrahydromethanopterin Smethyltransferase was affiliated to Methanosarcina, transforming one-carbon groups
including participates and methyltransferases in biosynthesis of folate. Acetyl-CoA
and phosphate serve as the substrates of the phosphate acetyltransferase enzyme,
while the two products of the enzyme include acetyl phosphate and CoA.
As illustrated by grey circles in Fig. 2.21, CO 2 reduction is another primary pathway to the methanogenesis in SHTP. The evidences for the pathway
included: (i) the major subunits of formate dehydrogenase; (ii) glycine hydroxymethyltransferase; (iii) methylenetetrahydromethanopterin dehydrogenase; (iv)
5,10-methylenetetrahydromethanopterin reductase; (v) subunits alpha and beta
of coenzyme F 420 hydrogenase; and (vi) alpha subunit of pyruvate ferredoxin
oxidoreductase. The major subunits of formate dehydrogenase exert catalyzation effects on the dehydrogenation of formic acid and through the CO 2 reduction pathway, they function as the electron donor for production of methane.
Glycine hydroxymethyltransferase appeared in Leclercia and Acinetobacter bacteria in Stages II and III. Methylenetetrahydromethanopterin dehydrogenase exerted
effects on the CH–NH group of donors with other acceptors and belongs to
Methanosarcina in all of the three stages. The enzyme has the two substrates
of 5,10-methylenetetrahydromethanopterin and coenzyme F 420 , whereas 5,10methenyltetrahydromethanopterin and reduced coenzyme F 420 are the two products.
The interesting thing is that 5,10-methylenetetrahydromethanopterin reductase and
alpha subunit of pyruvate ferredoxin oxidoreductase were merely obtained in Stage II
and belonged to Methanothermobacter in archaea. The identified proteins sub-units
alpha and beta of coenzyme F 420 hydrogenase were separately affiliated to Methanothermobacter and Methanococcus, which functioned as a deazaflavin analogue, and
used formic acid and hydrogen as electron donors to generate methane by reducing
CO 2 .
According to the blue circles in Fig. 2.21, a primary methylotrophic pathway was revealed by the identified proteins of methylamine–corrinoid protein
Co-methyltransferase assigned to Methanosarcina. This protein produces methane
through reduction of methyl with hydrogen in methyl compounds or via the dismutation of methyl compounds. Moreover, three proteins of subunit of methylCo M reductase were identified and found belonging to Methanothermobacter,
Methanosarcina, and Methanotorris in phylum Euryarchaeota during SHPT. It is
the terminal methyl carrier and the critical enzyme for all three pathways of methane
production (Jia et al. 2017b).