Methanotroph

Methanotrophs are bacteria that are able to grow using methane as their only source of carbon and energy. They require both single-carbon compounds and oxygen to survive, combining the two to form formaldehyde, which is then encorporated into organic compounds. They also characteristically have a system of internal membranes. Methanotrophs occur mostly in soils, and are especially common near environments where methane is produced. They are of special interest to researchers studying global warming.

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.