Complete Genome Sequence of Methylomonas koyamae LM6, a Potential Aerobic Methanotroph

Methylomonas koyamae LM6 is a potential methanotrophic bacterium of interest for methane bioconversion. Here, we report the complete genome sequence of M. koyamae LM6, which contains 4,337 predicted open reading frames on one chromosome (4,894,002 bp) and one plasmid (186,658 bp), with genes involved in methane oxidation.

Aerobic H2respiration enhances metabolic flexibility of methanotrophic bacteria

Methanotrophic bacteria are important soil biofilters for the climate-active gas methane. The prevailing opinion is that these bacteria exclusively metabolise single-carbon, and in limited instances, short-chain hydrocarbons for growth. This specialist lifestyle juxtaposes metabolic flexibility, a key strategy for environmental adaptation of microorganisms. Here we show that a methanotrophic bacterium from the phylum Verrucomicrobia oxidises hydrogen gas (H2) during growth and persistence.Methylacidiphilumsp. RTK17.1 expresses a membrane-bound hydrogenase to aerobically respire molecular H2at environmentally significant concentrations. While H2oxidation did not support growth as the sole electron source, it significantly enhanced mixotrophic growth yields under both oxygen-replete and oxygen-limiting conditions and was sustained in non-growing cultures starved for methane. We propose that H2is consumed by this bacterium for mixotrophic growth and persistence in a manner similar to other non-methanotrophic soil microorganisms. We have identified genes encoding oxygen-tolerant uptake hydrogenases in all publicly-available methanotroph genomes, suggesting that H2oxidation serves a general strategy for methanotrophs to remain energised in chemically-limited environments.