methylotrophic

Methylotrophy refers to the metabolic ability of certain microorganisms to use reduced single-carbon compounds as sources of carbon and energy. Methylotrophs can grow on C1 compounds such as methanol, formate, methylamine, or methane (the latter via specialized methanotrophs). Methanotrophs are methylotrophs that derive energy from methane oxidation and assimilate carbon from methane by one of two major biochemical routes.

Methylotrophs are broadly divided into obligate methylotrophs, which require C1 compounds to grow, and facultative methylotrophs, which can use C1 compounds but are not restricted to them. Methanotrophs are a prominent group within the methylotrophs; they typically inhabit soils, sediments, and aquatic environments where methane is present.

Metabolism in methylotrophs involves initial oxidation of the C1 substrate to formaldehyde, followed by energy generation and carbon assimilation. In methanotrophs, methane is oxidized to methanol by methane monooxygenase and then to formaldehyde by methanol dehydrogenase. Formaldehyde may be dissimilated to formate and CO2 for energy, or assimilated into biomass via the ribulose monophosphate (RuMP) pathway in Type I methanotrophs or via the serine cycle in Type II methanotrophs. Non-methanotrophic methylotrophs similarly metabolize C1 substrates and channel formaldehyde into central metabolism through RuMP or serine pathways. In methylotrophic yeasts and some fungi, assimilation uses the XuMP pathway, with formaldehyde incorporated into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate via enzymes such as dihydroxyacetone synthase.

Ecology and applications: Methylotrophs contribute to the global carbon cycle by consuming methanol and methane and linking C1 compounds to biomass. They hold potential for biotechnological uses, including bioremediation, methane mitigation, and the production of single-carbon metabolites and value-added products.