Methylococcales

Me.thy.lo.coc.ca' les. N.L. masc. n. Methylococcus type genus of the order; ‐ales ending to denote an order; N.L. fem. pl. n. Methylococcales the Methylococcus order.

Proteobacteria / Gammaproteobacteria / Methylococcales

Cells are Gram‐negative. Most species appear spherical, ovoid, or rod shaped. Species when motile use a single, unsheathed polar flagellum. Form type I intracytoplasmic membranes appearing as stacks of vesicular discs. Cells often contain polyhydroxyalkanoate and polyphosphate granules. Some species form cyst‐like resting bodies that provide different degrees of desiccation resistance but not heat resistance. Occur widely in terrestrial and marine environments that receive methane flux. Strictly aerobic. Most species are catalase and oxidase positive. Most species use only methane and methanol as sole sources of carbon and energy. Methane is always oxidized by particulate methane monooxygenase. Soluble methane monooxygenase activity is rare. Most species can use both inorganic and organic forms of nitrogen. Main fatty acids include saturated and monounsaturated fatty acids of C₁₄ to C₁₈ chain lengths with type depending on the genus and species. Main lipoquinones are either ubiquinone‐8 or 18‐methylene‐ubiquinone‐8. Main polar lipids include phosphatidylglycerol and/or phosphatidylethanolamine. The order includes members of the families Methylococcaceae and Methylothermaceae.

Type genus: Methylococcus Foster and Davis 1966, 1929^AL, emend. Bowman, Sly, Nichols and Hayward 1993, 748.