Energy metabolism in the Archaea has several similarities to either the Bacteria or the Eukarya subject to slight modifications example for The Entner-Doudoroff pathway for glucose catabolism. Pathways cannot be generalized because of the metabolic diversity of the Archaea but the metabolism of carbon sources resulting in the release of methane is unique. Substrates like as carbon monoxide, formate and carbon dioxide are metabolized anaerobically in the presence of hydrogen:
C1 compounds like as methanol, methylamine and dimethylsulfide are used when hydrogen is an electron donor in the following way:
However, some methanogens can use methanol in the absence of hydrogen:
Compounds such as acetate are cleaved in an acetotrophic process:
All these reactions are chemiosmotically linked to ATP synthesis. The acetotrophic reaction yields the least amount of energy per mole substrate whereas the CO2-type substrates yield the most.