Researchers Pin down One Source of a Potent Greenhouse Gas

Results suggest more methane may be released into atmosphere than thought

greenhouse gas
Old Woman Creek National Estuarine Research Reserve. Photo by Jordan Angle, courtesy of The Ohio State University.

A study of a Lake Erie wetland suggests that scientists have vastly underestimated the number of places methane-producing microbes can survive—and, as a result, today’s global climate models may be misjudging the amount of methane being released into the atmosphere.

In the journal Nature Communications, researchers at The Ohio State University and their colleagues describe the discovery of the first known methane-producing microbe that is active in an oxygen-rich environment.

Oxygen is supposed to be toxic to such microbes, called methanogens, but the newly namedCandidatus Methanothrix paradoxum thrives in it.

In fact, 80 percent of the methane in the wetland under study came from oxygenated soils. The microbe’s habitat extends from the deepest parts of a wetland, which are devoid of oxygen, all the way to surface soils.

“We’ve always assumed that oxygen was toxic to all methanogens,” saidKelly Wrighton, project leader and professor of microbiology at Ohio State. “That assumption is so far entrenched in our thinking that global climate models simply don’t allow for methane production in the presence of oxygen. Our work shows that this way of thinking is outdated, and we may be grossly under-accounting for methane in our existing climate models.”

More work needs to be done before researchers can determine exactly how much more methane is out there, but the microbe’s habitat appears to be global.

Searching publically available databases, the researchers found traces ofCandidatus Methanothrix paradoxum in more than 100 sites across North America, South America, Europe and Asia. The organism lives in rice paddies, wetlands and peatlands—even as far north as the Arctic. It just hadn’t been cataloged before, and its unusual metabolism hadn’t been discovered.

“We’ve always assumed that oxygen was toxic to all methanogens,” saidKelly Wrighton, project leader and professor of microbiology at Ohio State. “That assumption is so far entrenched in our thinking that global climate models simply don’t allow for methane production in the presence of oxygen. Our work shows that this way of thinking is outdated, and we may be grossly under-accounting for methane in our existing climate models.”

More work needs to be done before researchers can determine exactly how much more methane is out there, but the microbe’s habitat appears to be global.

Searching publically available databases, the researchers found traces ofCandidatus Methanothrix paradoxum in more than 100 sites across North America, South America, Europe and Asia. The organism lives in rice paddies, wetlands and peatlands—even as far north as the Arctic. It just hadn’t been cataloged before, and its unusual metabolism hadn’t been discovered.

Source : The Ohio State University