By Levi Clancy for Student Reader on
Methanogens are obligate anaerobic archaea that either consume or produce CO2, producing CH4. Methanotrophs consume CH4.
Requirements for growth:
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
CH3COO- + H2O → CH4 + HCO3 ΔG = -31