Methanotrophs at Work in the Gulf

From Robert Krulwich, National Public Radio

Last June, oceanography professor John Kessler of Texas A&M University visited BP's Gulf of Mexico accident site and found methane concentrations below the surface that were, "on average about 100,000 times greater than background." He told Living On Earth, "We even saw a few locations that were starting to push the limits of a million times above background."

Last August, Kessler sailed out on the NOAA ship Pisces to check on the gas plume. Three months had passed. 120 days. He looked. He looked again. The gas was gone.

Last month he published a paper in Science that points the finger at hard-working methanotrophs acting as "teeny janitors."

Kessler et al's abstract:

Methane was the most abundant hydrocarbon released during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. Beyond relevancy to this anthropogenic event, this methane release simulates a rapid and relatively short-term natural release from hydrates into deepwater. Based on methane and oxygen distributions measured at 207 stations throughout the affected region, we find that within ~120 days from the onset of release ~3.0 × 1010 to 3.9 × 1010 moles of oxygen were respired, primarily by methanotrophs, and left behind a residual microbial community containing methanotrophic bacteria. We suggest that a vigorous deepwater bacterial bloom respired nearly all the released methane within this time and that by analogy, large-scale releases of methane from hydrate in the deep ocean are likely to be met by a similarly rapid methanotrophic response.

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