Methanotroph

Methanotrophs (sometimes called methanophiles) are prokaryotes that metabolize methane as their only source of carbon and energy. They can grow aerobically or anaerobically and require single-carbon compounds to survive. These Methanotrophs are currently being modified to absorb methane from the atmosphere, because methane released into the atmosphere contributes to greenhouse gasses, which heat up the earth and cause global warming.

Under aerobic conditions, they combine oxygen and methane to form formaldehyde, which is then incorporated into organic compounds via the serine pathway or the ribulose monophosphate (RuMP) pathway. Type I methanotrophs are part of the Gammaproteobacteria and they use the RuMP pathway to assimilate carbon. Type II methanotrophs are part of the Alphaproteobacteria and utilize the Serine pathway of carbon assimilation. They also characteristically have a system of internal membranes within which methane 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, as they are significant in the global methane budget. They have also been used to produce animal feed from natural gas.

Differences in the method of formaldehyde fixation and membrane structure divide the methanotrophs into several groups. These include the Methylococcaceae and Methylocystaceae. Although both are included among the Proteobacteria, they are members of different subclasses. Other methanotroph species are found in the Verrucomicrobiae.

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