The genus ''Methylophaga'' consists of

halophilic The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...

methylotrophic members of the ''

Gammaproteobacteria Gammaproteobacteria is a class of bacteria in the phylum Pseudomonadota (synonym Proteobacteria). It contains about 250 genera, which makes it the most genera-rich taxon of the Prokaryotes. Several medically, ecologically, and scientifically imp ...

'', all of which were isolated from marine or otherwise low water activity environments, such as the surface of marble or hypersaline lakes. The cells are rod-shaped.Garrity, George M. (2005). Bergey's manual of systematic bacteriology, Volume Two: The Proteobacteria, Part B: The Gammaproteobacteria. New York: Springer . and are motile by a single polar

flagellum A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

. (with the possible exception of ''M. aminisulfidivorans'' which has been described as being non-motile) When ''Methylophaga'' was defined originally as a genus in 1985, all species known at that time were

auxotrophic Auxotrophy ( grc, αὐξάνω "to increase"; ''τροφή'' "nourishment") is the inability of an organism to synthesize a particular organic compound required for its growth (as defined by IUPAC). An auxotroph is an organism that displays this ...

for vitamin B12, however, many species were found to be non-auxotrophic and so this is no longer a defining characteristic. ''Methylophaga'' spp. are the dominant

methylotroph Methylotrophs are a diverse group of microorganisms that can use reduced one-carbon compounds, such as methanol or methane, as the carbon source for their growth; and multi-carbon compounds that contain no carbon-carbon bonds, such as dimethyl et ...

s in the upper layers of the oceans, and have key roles in the biogeochemical cycling of

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...

monomethylamine Methylamine is an organic compound with a formula of . This colorless gas is a derivative of ammonia, but with one hydrogen atom being replaced by a methyl group. It is the simplest primary amine. Methylamine is sold as a solution in methanol, ...

dimethylsulfide Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. Dimethyl sulfide is a flammable liquid that boils at and has a characteristic disagreeable odor. It is a component of the smell produced from cook ...

and

methyl bromide Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula C H3 Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozon ...

. All known species are methylotrophic and grow on

and usually other one-carbon compounds as well as

fructose Fructose, or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galacto ...

, '' Methylophaga thiooxydans'' has been shown to grow on substituted thiophenes. Chemolithoheterotrophy has been observed in both '' Methylophaga thiooxydans'' and '' Methylophaga sulfidovorans'', at the expense of

thiosulfate Thiosulfate ( IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula . Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, ...

and

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...

, respectively and may be a wider property in the genus as a whole.

References

Bacteria genera Piscirickettsiaceae {{Gammaproteobacteria-stub