Widespread soil bacterium that oxidizes atmospheric methane.

Area of Science:

• Microbiology
• Environmental Science
• Biogeochemistry

Background:

• Methane (CH4) is a significant greenhouse gas with increasing atmospheric concentrations.
• Microbial oxidation in soils is the only known biological methane removal process.
• Cultivating bacteria capable of utilizing atmospheric CH4 has been a major challenge.

Purpose of the Study:

• To isolate and characterize bacteria that can grow on atmospheric concentrations of methane.
• To investigate the metabolic capabilities and genomic features of these methanotrophs.
• To assess the prevalence of atmospheric methane utilization among related bacterial species.

Main Methods:

• Isolation and cultivation of bacteria from soil samples.
• Methane oxidation experiments and 13C-single cell isotope analyses.
• Whole-genome sequencing and analysis of Methylocapsa gorgona MG08.

Main Results:

• Isolation of Methylocapsa gorgona MG08, a bacterium that grows on atmospheric CH4.
• Demonstration of aerobic CH4 oxidation and assimilation of carbon from CH4 and CO2.
• Identification of the highest specific affinity for CH4 among cultivated methanotrophs.
• Confirmation of atmospheric CH4 utilization in related Methylocapsa species.
• Genomic analysis revealing pathways for carbon assimilation, CO2 fixation, and trace gas oxidation.

Conclusions:

• The ability to utilize atmospheric methane for growth is more widespread than previously thought.
• Methylocapsa gorgona possesses unique metabolic traits for efficient atmospheric CH4 consumption.
• These findings highlight the significant role of soil microbes in regulating atmospheric greenhouse gas levels.