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 bonds, such as dimethyl ether and dimethylamine. This group of microorganisms also includes those capable of assimilating reduced one-carbon compounds by way of carbon dioxide using the ribulose bisphosphate pathway. These organisms should not be confused with methanogens which on the contrary produce methane as a by-product from various one-carbon compounds such as carbon dioxide. Some methylotrophs can degrade the greenhouse gas methane, and in this case they are called methanotrophs. The methanotroph Methylococcus capsulatus is used to degrade methane and other pollutants. The abundance, purity, and low price of methanol compared to commonly used sugars make methylotrophs competent organisms for production of amino acids, vitamins, recombinant proteins, single-cell proteins, co-enzymes and cytochromes.
Methylotrophic organisms are able to grow at the expense of one or more of the compounds typically used by methophiles, but cannot use methane. Methylotrophs are a diverse group, including both Gram-negative and Gram-positive genera. None of them make resting structures like exospores and cyst and none of them have the complex intracellular membrane systems that characterize methanotrophs growing on methane
There are two sub groups: 1- obligate methylotrophs. 2- facultative methylotrophs.
A single obligate methylotroph (methylophilus) is known. It is Gram-negative, polarly flagellated rod capable of rapid growth with methanol. Some strains can also utilize formaldehyde or methylamines. Carbon is assimilated via the ribulose mono phosphate pathway.
It is relatively widely distributed trait among heterotrophic bacteria. It may also be common among chemoautotrophs: several thiobacilli and nitrifying bacteria can drive CO2 assimilation via the Calvin-Benson cycle by formate oxidation.
Examples of methylotrophs:
- Anthony, C. "The Biochemistry of Methylotrophs". Academic press, 1982, p. 2-3