Methylotrophic bacteria are recognized by their ability to use, as sole carbon and energy sources for growth, compounds that contain no carbon-carbon bonds and to assimilate carbon as formaldehyde or a mixture of formaldehyde and carbon dioxide. 16 They are different from methanogenic bacteria which produce methane from organic compounds. Growth substrates often used by methylotrophs are the following: methane, methanol, formaldehyde, formate, dimethyl ether, methyl formate, formamide, and methylamines. Not all of the methylotrophs can grow on methane. Those microorganisms capable of growth on methane are called methanotrophs. No obligate methylotrophs so far described are capable of growth on formate. Facultative methylotrophs can also grow on a variety of organic multicarbon compounds.