A methanotrophic bacterium to enable methane removal for climate mitigation

Abstract

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 2 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, Methylotuvimicrobium buryatense 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.

Living emission abolish filters (LEAFs) for methane mitigation: design and operation

“…LEAF units have potential to be applied to a variety of sources with high to low methane inlet concentration loads at a variety of flow rates. The system has yet to be tested at atmospheric methane concentrations of 1.9 ppm (∼0.0002%), but a recent study has emerged demonstrating that in liquid culture Methylotuvimicrobium buryatense 5GB1 was able to grow and consume methane at 200 ppm (∼0.02%) exhibiting the possibilities of using methanotrophic bacteria to mitigate atmospheric methane [65].…”

Atmospheric methane removal may reduce climate risks

“…For light-based reactors, including those that use photocatalysts and photolysis-based radical generation, the quantum efficiency (the ratio of oxidized methane molecules to incident photons) will need to be increased-from the current high of 0.8% potentially to at least 9% [15,19]. For bioreactors, substantial technological breakthroughs are required to lower the lowest concentration at which they can operate from ∼500 ppm down to 1.9 ppm [20]. The requirements that these technologies will have to meet to achieve cost-effectiveness and scalability become even more stringent when considering the technoeconomics and energetics of moving climate-relevant quantities of air.…”

Metabolic Basis for the Microbial Oxidation of Atmospheric Methane

“…SC2 (3.4 × 10 − 11 L cell − 1 h − 1 ) 24 , the MOB with the fourth highest for CH 4 known so far. However, the different experimental setups and CH 4 concentrations used to determine might render the comparisons invalid 24,57 . Nevertheless, our results indicate that 58 the speci c a nity ( , rather than the a nity (K m(app) ), is the suitable measure to determine the capacity of methanotrophs to oxidize atmospheric CH 4 , as previously suggested for oligotrophic substrate uptake at low concentrations by Button 58 ,.…”