Microbial Community Interactions Drive Methane Consumption in Lakes
Understanding interactions among organisms in complex microbial communities sheds new light on globally significant environmental processes.
Large amounts of methane, a potent greenhouse gas, are produced as a byproduct during decomposition of plant matter in the sediments of lakes and wetlands. Bacteria known as methanotrophs consume much of this methane before it can enter atmosphere. In a recent study, researchers examined community interactions among methanotrophs and other types of microbes that control this important process.
The biological mechanisms underlying many important environmental processes can be understood only by examining cooperative processes performed by diverse communities of microbes. This study uses an elegantly constructed model experiment and genomic analysis to examine the genetic basis of these interactions and determine how they influence microbial consumption of methane in lake sediments.
Several decades of research have demonstrated the importance of bacterial methanotrophs in carbon cycling processes of lakes, wetlands, and a variety of other environments. However, methanotrophs exist as members of diverse communities of regularly co-occurring non-methanotrophic microbes, and the roles of these organisms in methane cycling are not well understood. In a recent study, researchers at the University of Washington assembled an experimental model community of methanotrophs and associated non-methanotrophic microbes previously isolated from lake sediments. Using a community-scale metaomics analysis of shifts in gene expression, the team tracked how the associated organisms influenced each other during methane-driven growth. The presence of non-methanotrophs was shown to trigger an enzymatic and metabolic shift in the methanotrophs, resulting in conversion of a portion of the available methane into methanol, which was released to fuel the growth of these microbes. Not yet clear is if the methanotrophs derive some form of reciprocal benefit from this “cross-feeding,” or if this represents a type of parasitism. In either case, these findings considerably alter current understanding of methanotrophy as it occurs in complex environmental communities and suggest that much remains to be learned about the basic biological mechanisms driving an important element of the global carbon cycle.
University of Washington
This study was supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Genomic Science program under award DE-SC-0010556.
S. M. B. Krause, T. Johnson, Y. S. Karunaratne, Y. Fu, D. A. C. Beck, L. Chistoserdova, and M. E. Lidstrom, “Lanthanide-dependent cross-feeding of methane-derived carbon is linked by microbial community interactions.” Proceedings of the National Academy of Sciences (USA) 114(2), 358-63 (2017). DOI: 10.1073/pnas.1619871114.