Methanogenesis acetoclastic

Fig. 22.8. Energy yields for various anaerobic (top) and aerobic (bottom) metabolisms during mixing of a subsea hydrothermal fluid with seawater, expressed as a function of temperature, per kg of hydrothermal water. Energy yields for acetoclastic methanogenesis and acetotrophic sulfate reduction under oxic conditions are hypothetical, since microbes from these functional groups are strict anaerobes and cannot live in the presence of dioxygen.

Fig. 33.3. Steady-state distribution of microbial activity and groundwater composition in an aquifer hosting acetotrophic sulfate reduction and acetoclastic methanogenesis, obtained as the long-term solution to a reactive transport model.

Fig. 33.4. Factors controlling rates of microbial activity in the simulation depicted in Figure 33.3, for acetotrophic sulfate reduction (top) and acetoclastic methanogenesis (bottom). Factors include the thermodynamic potential factor Ft, kinetic factors FD = wac/C ac + Kq) and FA = mso4/(mso4 + K A), and biomass concentration [A],...

In Methanosarcina and Methanothrix" CH3-C0M, an intermediate of acetoclastic methanogenesis, is formed by transfer of the methyl group of acetyl-CoA to CoM [231,237,239,242]. This conversion. 

Methanogenesis from acetate in extracts of Methanosarcina does not require membrane addition [260]. However, this does not exclude a function for cytochromes in acetoclastic methanogenesis by whole cells. Rather, the role of H2 in cell extracts, the ability of cytochrome b from Methanosarcina species to react with CO, and the observation that membrane-bound cytochromeb of M. barkeri is reduced by H2, and is oxidized by CH3-CoM -I- ATP or CH3-C0M + acetyl-phosphate, all point to the participation of cytochromes in Methanosarcina. A role of cytochromes in transport of electrons generated from carboxyl-group oxidation to the heterodisulfide reductase is a logical hypothesis. 

Penning, H., P. Claus, P. Casper, and R. Conrad. 2006. Carbon isotope fractionation during acetoclastic methanogenesis by Methanosaeta concilii in culture and a lake sediment. Appl. Environ. Microbiol. 72 5648-5652. 

Mefhanogenesis include processes, which with the participation of archaebacteria form CH. Up to 4 processes of methanogenesis are identified. But the main among them are acetoclastic and hydrogenotrophic. Others play a secondary role. 

Acetoclastic methanogenesis is associated with the reaction of disproportionation, i.e., fermentation of the acetate. It includes the CH formation at the expense of acetic acid methyl group ... 

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