A laboratory study of the long-term impacts of a methane pulse event on a soil microbial community

Methane is a potent greenhouse gas and soils can act as both a source and sink. The presence of a methane flux can promote an increase in methanotrophs; however, broader changes to the soil community are not well documented. Shifts within the differing methanotrophic niches are also poorly understood. This work explores the resistance and resilience of a soil microbial community over 18 months after exposure to methane pulses. Methods Quantitative PCR (qPCR) of genes involved in methanotrophy (pmoA, mmoX, and Methylocella-specific mmoX), 16S rRNA gene sequencing and methane oxidation rate measurements were undertaken immediately after the pulse and after 5, 9, 12, and 18 months. Conclusions Compared to the control, the pulse altered the methanotrophic community, which remained disturbed throughout the experiment. Stimulation of methanotrophs resulted in increases in methane oxidation rates which declined through time. The relative abundance of pmoA increased in response to the methane pulse, while mmoX was greater in the control. The broader microbial community was also disturbed by the methane pulse.