Methanogen

By Levi Clancy for Student Reader on
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Methanogens are obligate anaerobic archaea that either consume or produce CO2, producing CH4. Methanotrophs consume CH4.

Requirements for growth:

  • Anoxic sediments

  • Animal digestive systems (rumen of cattle, sheep, elk, camels)

  • Geothermal sources of H2 + CO2

  • Artificial biodegradation facilities

  • Endozymbiots of anaerobic protozoa

As herbivores, they live off the complex carbohydrate cellulose. Methane produced in rumen creates pressure, thereby causing risk of explosion. H2 is methanogenic e- donor. Hydrogen consumption of methanogens coupled to hydrogren production of something else. Why syntrophy? Mutual beenfit. Complementation of two or more organisms metabolic capabilities to catabolize a substance not cpaable of being catabolized by either one alone.

Methanogenic substrates include CO2-type substrates (including formate, CO2+H2 combined; CO): 4H2 + CO2 → reduction → CH4 + 2H2O ΔG = -131 kJ.

Methyl substrates (methanol):

CH3OH + H2 → CH4 + H2O ΔG = -113 kJ
4CH3OH → 3CH4 + CO2 + 2H2O ΔG = -319 kJ

Acetotrophic substrates:

CH3COO- + H2O → CH4 + HCO3 ΔG = -31