The Scientific Activist

From today's (well, technically, tomorrow's) New Zealand Herald:

Creature from hell promises salvation
by Errol Kiong

Scientists have discovered a methane-eating bacterium at Hell's Gate in Rotorua which may offer hope for global warming.

Researchers at GNS Science hope their discovery of the bacterium could one day be used to cut down methane gas emissions from landfills and geothermal power stations.

The bug is part of a group of methane-eating micro-organisms known as methanotrophs, but this one is able to live in hotter and much more acidic conditions.

This article--sporting a wildly exaggerated (but entertaining) headline--is referring to one of two papers published online in Nature on November 14th, each reporting a newly-discovered extremophilic methanotrophic bacterium from the Verrucomicrobia phylum (extremophilic = living in an extreme environment, in this case low pH and high temperature; methanotrophic = able to use methane as its sole carbon source). Both groups discovered their bacteria in areas of high geothermal activity: Hell's Gate, New Zealand for Dunfield et al. and Solfatara, Italy for Pol et al. These findings are significant because (1) all previously known methanotrophs were members of the Proteobacteria phylum, (2) the newly-discovered bacteria thrive in much more extreme conditions than known methanotrophs, (3) the methane metabolism pathways in the newly-discovered bacteria are phylogenetically distant from previously known pathways, (4) this might be a widespread phenomenon, and (5) the bacteria could be useful in reducing emissions of methane (a greenhouse gas) from certain areas.

Analysis of the novel bacteria's pmoA genes (which encode a portion of the methane monooxygenase enzyme) in both studies found pmoA genes with low sequence identity to those in other methanotrophs. Also, in both studies, researchers were unable to identify many other genes involved in pathways related to methanotrophy. These results indicate that the Verrucomicrobia methanotrophs diverged from the Proteobacteria methanotrophs long ago, and the Verrucomicrobia methanotrophs did not acquire their ability to survive on methane from lateral gene transfer from the Proteobacteria methanotrophs. In short, the newly-discovered bacteria are quite unique. The Verrucomicrobia phylum is relatively unexplored, but both groups present evidence that Verrucomicrobia methanotrophs are genetically diverse and fairly widespread.

Methane is currently responsible for about 18% of the greenhouse effect, which causes global warming. Carbon dioxide is by far the greatest contributor to global warming. Methane is a more potent greenhouse gas than carbon dioxide, but it is present at a much lower concentration in the Earth's atmosphere. Given their ability to thrive in more extreme environments, Verrucomicrobia methanotrophs (as noted in the media coverage) could conceivably be useful in reducing methane emissions from geothermal power stations, landfills, and other areas where methane is released. More significantly, though, these bacteria are likely responsible for keeping natural methane emissions much lower than they would be otherwise. Regardless, these bacteria are not a quick fix for global warming, and the only way to truly address global warming will still be through reducing carbon dioxide emissions.

Dunfield, P.F., Yuryev, A., Senin, P., Smirnova, A.V., Stott, M.B., Hou, S., Ly, B., Saw, J.H., Zhou, Z., Ren, Y., Wang, J., Mountain, B.W., Crowe, M.A., Weatherby, T.M., Bodelier, P.L., Liesack, W., Feng, L., Wang, L., Alam, M. (2007). Methane oxidation by an extremely acidophilic bacterium of the phylum Verrucomicrobia. Nature, 450(7171), 879-882. DOI: 10.1038/nature06411

Pol, A., Heijmans, K., Harhangi, H.R., Tedesco, D., Jetten, M.S., Op den Camp, H.J. (2007). Methanotrophy below pH 1 by a new Verrucomicrobia species. Nature, 450(7171), 874-878. DOI: 10.1038/nature06222