Methanotroph 1343401 222799958 2008-07-01T04:37:58Z Numbo3-bot 7118326 robot Adding: [[fr:Méthanotrophe]] '''Methanotrophs''' are [[bacterium|bacteria]] that are able to grow using [[methane]] as their only source of [[carbon]] and [[energy]]. They can grow [[Cellular respiration#Aerobic respiration|aerobically]] or [[Anaerobic respiration|anaerobically]] and require single-carbon [[chemical compound|compound]]s to survive. Under aerobic conditions, they combine [[oxygen]] and methane to form [[formaldehyde]], which is then incorporated into organic compounds. They also characteristically have a system of internal membranes within which methane [[redox|oxidation]] occurs. Methanotrophs occur mostly in soils, and are especially common near environments where methane is produced. Their habitats include oceans, mud, marshes, underground environments, soils, rice paddies and landfills. They are of special interest to researchers studying [[global warming]]. Gratuitous detoxification of some environmental contaminants such as [[organochloride|chlorinated hydrocarbon]]s by methanotrophs have made them attractive models for such [[bioremediation]] processes. Equally methane is a potential [[greenhouse gas]] far more potent that [[carbon dioxide]]. Therefore methanotrophs play a major role in the reduction of the release of methane into the atmosphere from environments such as rice paddies, landfills, bogs and swamps where methane production is relatively high. Differences in the method of formaldehyde fixation and membrane structure divide the methanotrophs into two groups, called type I and type II. These are respectively classified as the [[Methylococcaceae]] and [[Methylocystaceae]]. Although both are included among the [[Proteobacteria]], [[RNA]] trees place them in different subgroups, so they are not closely related. However, they appear closely related to groups that oxidize [[ammonia]]; these may also oxidize methane, although they cannot use it as a carbon source. Methanotrophy is a special case of methylotrophy, using single-carbon compounds that are less oxidized than carbon dioxide. Most methylotrophs, however, can also make use of multi-carbon compounds which differentiates them from methanotrophs that are usually [[Growth medium|fastidious]] methane and methanol oxidizers. Investigations in marine environments revealed that methane can be oxidized anaerobically by consortia of methane oxidizing [[archaea]] and [[sulfate]]-reducing bacteria. [[Anaerobic oxidation of methane]] (AOM) mainly occurs in anoxic marine sediments. The exact mechanism of methane oxidation under anaerobic conditions is still a topic of debate but the most widely accepted theory is that the archaea use the reversed [[methanogenesis]] pathway to produce carbon dioxide and another, unknown substance. This unknown intermediate is then used by the sulfate-reducing bacteria to be able to gain energy from the reduction of sulfate to [[hydrogen sulfide]]. The anaerobic methanothrophs are not related to the known aerobic methanotrophs; the closest cultured relative to the anaerobic methanotrophs are the [[methanogen]]s in the order of [[Methanosarcinales]]. ==External links== * [http://www.amethox.com/ Anaerobic methane oxidation] * [http://www.gns.cri.nz/news/release/20071122methane.html METHANE-EATING BUG HOLDS PROMISE FOR CUTTING GREENHOUSE GAS]. Media Release, GNS Science, New Zealand [[Category:Proteobacteria]] {{bacteria-stub}} [[fr:Méthanotrophe]] [[nl:Methanotrofie]] [[ru:Метанотрофы]] [[uk:Метанотрофи]]