CO in methanogenesis

Although CO is present in methanogenic environments, an understanding of CO metabolism by methanogens has lagged behind other methanogenic substrates and investigations of CO metabolism in non-methanogenic species. This review features studies on the metabolism of CO by methanogens from 1931 to the present. The pathways for CO metabolism of freshwater versus marine species are contrasted and the ecological implications discussed. The biochemistry and role of CO dehydrogenase/acetyl-CoA synthase in the pathway for conversion of acetate to methane and biosynthesis of cell carbon is presented. Finally, a proposal for the role of CO and primitive forms of the CO dehydrogenase/acetyl-CoA synthase in the origin and early evolution of life is discussed.