The Science

In a Lake Erie wetland, scientists showed that microbes produce methane in an oxygen-rich environment. This finding disproves the long-accepted idea that oxygen limits microbe’s ability to produce methane. The team performed DNA sequence analyses of samples across the wetland. They uncovered a dominant new species of methane-producing Archaea. This Archaea was also present in samples from many different oxygen-rich ecosystems.

The Impact

Existing global climate models do not take into account microbes producing methane, a greenhouse gas, in oxygenated surface soils. This study indicates current global climate models could be greatly underestimating where these microbes live. The study also sheds light on a new Archaea species. This species is probably responsible for a large fraction of methane emissions in oxygen-containing soils.

Summary

A group of scientists set out to sample microbes living in Old Woman Creek National Estuarine Research Reserve, a wetland of Lake Erie, in an effort to start to piece together the broad picture of methane production. However, they made an unexpectedly important discovery when they found oxygen-rich soils containing up to 10 times more methane than non-oxygenated soils. Moreover, up to 80 percent of the net methane emissions was a result of microbial methane production in oxygenated soils. Through DNA sequencing of microbes from these soils, the research team discovered a previously uncatalogued methane-producing (methanogen) organism that belongs to the Archaea group of microbes and they named it Candidatus Methanothrix paradoxum. This microorganism not only thrives in the oxygen-rich wetland, but the researchers also found evidence of its presence at more than 100 diverse environments across the world (rice paddies, wetlands, and peatlands), suggesting that this microbe significantly contributes to methanogenesis in a wide variety of oxygen-containing habitats. The results from this study indicate global climate models have greatly underestimated the role methanogens play in global methane emissions and their effects on the climate.

Funding

This work was supported by the Office of Biological and Environmental Research (BER) within the Department of Energy’s Office of Science (SC) Early Career Research Program award to Kelly Wrighton, including contributions from BER’s Ameriflux and Regional and Global Climate Modeling programs supported under BER, the SC Graduate Student Research Program, and the SC user facilities Environmental Molecular Sciences Laboratory and the Joint Genome Institute. The authors also acknowledge support from the Ohio Water Development Authority and the National Science Foundation.