초록
<▼1><P><B>Significance</B></P><P>Atmospheric methane abundance has risen to a historically high value at 1.92 ppm in 2023 and continues to increase rapidly. A key natural sink for methane is attributed to aerobic methanotrophs that can actively oxidize methane and assimilate the carbon into biomass, and thus, they are candidates for methane removal technology. We demonstrate here that an extant gammaproteobacterial methanotroph, <I>Methylotuvimicrobium buryatense</I> 5GB1C, can grow at low methane concentrations in the range from 200 ppm to 1,000 ppm and exhibits greater methane consumption rates at both low and high methane compared to other methanotroph strains. These features make this strain a promising candidate for methane removal technology at emission sites with enriched methane in air.</P></▼1><▼2><P>The rapid increase of the potent greenhouse gas methane in the atmosphere creates great urgency to develop and deploy technologies for methane mitigation. One approach to removing methane is to use bacteria for which methane is their carbon and energy source (methanotrophs). Such bacteria naturally convert methane to CO<SUB>2</SUB> and biomass, a value-added product and a cobenefit of methane removal. Typically, methanotrophs grow best at around 5,000 to 10,000 ppm methane, but methane in the atmosphere is 1.9 ppm. Air above emission sites such as landfills, anaerobic digestor effluents, rice paddy effluents, and oil and gas wells contains elevated methane in the 500 ppm range. If such sites are targeted for methane removal, technology harnessing aerobic methanotroph metabolism has the potential to become economically and environmentally viable. The first step in developing such methane removal technology is to identify methanotrophs with enhanced ability to grow and consume methane at 500 ppm and lower. We report here that some existing methanotrophic strains grow well at 500 ppm methane, and one of them, <I>Methylotuvimicrobium buryatense</I> 5GB1C, consumes such low methane at enhanced rates compared to previously published values. Analyses of bioreactor-based performance and RNAseq-based transcriptomics suggest that this ability to utilize low methane is based at least in part on extremely low non-growth-associated maintenance energy and on high methane specific affinity. This bacterium is a candidate to develop technology for methane removal at emission sites. If appropriately scaled, such technology has the potential to slow global warming by 2050.</P></▼2>