Methylobacterium extorquens is a pink-pigmented facultative methylotrophic Gram-negative bacterium first isolated in 1960 in Oxford as an airborne contaminant growing on methylamine. The trait common to all Methylobacterium species is the ability to grow on one or several reduced one carbon (C1) compounds other than methane, most prominently methanol. They are often found associated with plants. It has been used as a workhorse to characterize the serine cycle for assimilation of the C1-unit of methylene tetrahydrofolate, a central intermediate in methylotrophic metabolism, and more recently the ethylmalonyl-CoA pathway for glyoxylate regeneration.

Methylobacterium strain DM4 was isolated from industrial wastewater sludge in Switzerland, as part of efforts to characterize microorganisms able to degrade the organohalogenated pollutant dichloromethane (DCM). Unlike methanol and methylamine, which are mainly produced naturally, DCM is a highly produced synthetic compound which is rated as potentially carcinogenic for humans. It is highly volatile and water-soluble, making it a widespread contaminant in the environment. Most of the genomic determinants associated with methylotrophy are nearly identical in all strains with exceptions that illustrate the metabolic and genomic versatility of Methylobacterium species. M.extorquens (strain ATCC 14718 / DSM 1338 / AM1, METEA) possesses a unique methylamine dehydrogenase and accessory functions gene cluster (mau), indicating that strain DSM 5838 / DM4 employs an alternative system for growth with methylamine, while the dcm (dichloromethane degradation) gene region is present only in strain DM4. M. extorquens contains large sets of insertion elements, many of them strain-specific, suggesting an important potential for genomic plasticity (adapted from PMID 19440302).