Studying Methanotrophic Bacterial Diversity in Soils Using Next Generation Sequencing.

Methane (CH₄) is a potent greenhouse gas found at lower concentrations in the atmosphere than carbon dioxide (CO₂) but, on a similar mass basis, has a global warming potential 23 times greater than CO₂. Land-use practices impact the rate of CH₄ oxidation in soil, with a number of studies indicating that agricultural lands, undisturbed grasslands and pristine forests have different rates of CH₄ oxidation. Methanotrophs, or methane-oxidizing bacteria (MOB) present in aerobic soils oxidize CH₄ oxidation and hence serve as the only known biological sink of atmospheric CH₄. We hypothesize that since CH₄ oxidation rates vary in soils under different land-use practices, this variation is indicative of methanotrophic bacterial diversity in those soils.

The objective of our study is to determine diversity of methanotrophic bacteria in soils under varying land-use practices, using next generation sequencing technique. The land use patterns include agricultural soils with varying crop rotations (under long-term tillage and long-term no-tillage), grassland soils and forest soils. We targeted methanotroph-specific phylogenetic markers to characterize the nature and abundance of the bacteria. A total of three region-specific primer sets were designed to analyze diversity amongst six treatments spread over two geographic locations in Ohio. The Illumina MiSeq platform was used to obtain sequences by assembling paired-end reads. After initial data trimming, QIIME was used to analyze the high-throughput sequencing data.

Our study represents a rapid method to identify methanotrophic bacterial diversity in soils under various land-use systems. This will lead to a better understanding of how these systems affect the concentration of CH₄ in the atmosphere. The results of this study will contribute to addressing a broader goal of identifying the role of land use in climate change mitigation strategies.