Figure 2.
Methanogenesis pathways: Hydrogenotrophic (a), methylotrophic (b), and aceticlastic (c). The methanogenesis common reactions are marked red. fdh: formate dehydrogenase; fmd: formylmethanofuran dehydrogenase; ftr: formylmethanofuran-tetrahydromethanopterin formyl-transferase; mch: methenyl-tetrahydromethanopterin cyclohydrolase; mtd: methylenetetrahydromethanopterin dehydrogenase; mer: methylenetetrahydromethanopterin reductase; mtr: methyl-tetrahydromethanopterin S-methyltransferase; mcr: methyl-coenzyme M reductase; mt: methyltransferase; hdr: heterodisulfide reductase; ech: energy-converting hydrogenase; CODH-ACS: CO dehydrogenase/acetyl-CoA synthase. The figure was adapted from Niu et al. [303].