Methanogenesis

In some circumstances, for instance in the rumen, where acetate is largely absorbed into the bloodstream of the host, the contribution of H2 to methanogenesis is greater.

[5] However, depending on pH and temperature, methanogenesis has been shown to use carbon from other small organic compounds, such as formic acid (formate), methanol, methylamines, tetramethylammonium, dimethyl sulfide, and methanethiol.

The mechanism for the conversion of CH3–S bond into methane involves a ternary complex of the enzyme, with the substituents forming a structure α2β2γ2.

Organisms performing AOM have been found in multiple marine and freshwater environments including methane seeps, hydrothermal vents, coastal sediments and sulfate-methane transition zones.

[8] These organisms may accomplish reverse methanogenesis using a nickel-containing protein similar to methyl-coenzyme M reductase used by methanogenic archaea.

During the decay process, electron acceptors (such as oxygen, ferric iron, sulfate, and nitrate) become depleted, while hydrogen (H2) and carbon dioxide accumulate.

Methanogenesis effectively removes the semi-final products of decay: hydrogen, small organics, and carbon dioxide.

In the rumen, anaerobic organisms, including methanogens, digest cellulose into forms nutritious to the animal.

[18][19][20] Methanogenesis can also be beneficially exploited, to treat organic waste, to produce useful compounds, and the methane can be collected and used as biogas, a fuel.

The justification is that on an astronomical timescale, methane in the atmosphere of an Earth-like celestial body will quickly dissipate, and that its presence on such a planet or moon therefore indicates that something is replenishing it.

[28] It is argued that atmospheric methane can come from volcanoes or other fissures in the planet's crust and that without an isotopic signature, the origin or source may be difficult to identify.

[29][30] On 13 April 2017, NASA confirmed that the dive of the Cassini orbiter spacecraft on 28 October 2015 discovered an Enceladus plume which has all the ingredients for methanogenesis-based life forms to feed on.