methanolutilizing

Methanolutilizing refers to organisms and biological processes that metabolize methanol as a source of carbon and energy. This term encompasses a group of organisms known as methylotrophs, including certain bacteria, yeasts, and archaea, as well as the enzymatic pathways they employ to process methanol.

The initial oxidation step in methanolutilizing systems is carried out by different enzymes depending on the lineage. In many methylotrophic bacteria, methanol dehydrogenases such as MxaFI and XoxF catalyze the conversion of methanol to formaldehyde, with cofactors ranging from calcium to lanthanides. In several methylotrophic yeasts and some fungi, methanol oxidation occurs in peroxisomes via alcohol oxidase, generating formaldehyde as an early intermediate.

Formaldehyde fate distinguishes assimilation from dissimilation. For assimilation, formaldehyde is incorporated into biomass through pathways such as the ribulose monophosphate (RuMP) cycle in bacteria or the XuMP and serine pathways in yeasts. Key enzymes include dihydroxyacetone synthase and related transketolases, which funnel carbon into central metabolism. For dissimilation, formaldehyde can be further oxidized to formate and then to CO2 by formaldehyde dehydrogenase and formate dehydrogenase, releasing energy in the process.

Ecology and applications are broad. Methanol-utilizing organisms inhabit plant-associated environments, soils, and aquatic ecosystems, contributing to global carbon cycling and bioremediation. Industrially, methylotrophic yeasts such as Pichia pastoris are used as expression hosts for recombinant proteins and for biotransformations that utilize methanol as a feedstock.

Genetics and evolution show that methylotrophy has evolved multiple times across diverse lineages, often involving conserved clusters of genes for methanol oxidation, formaldehyde processing, and carbon assimilation, illustrating convergent solutions to methanol metabolism.