With support from the NASA Astrobiology Program, researchers at the Massachusetts Institute of Technology (MIT) have discovered a new bacterial gene that could provide clues about how life survives in some of Earth’s most extreme environments.
The gene codes for a protein, named HpnR, that is responsible for producing bacterial lipids known as 3-methylhopanoids. These lipids could help prepare nutrient-starved microbes to make a sudden appearance in nature when conditions are favorable. It allows the organisms to survive in extreme, oxygen-depleted environments until food — such as methane and the oxygen needed to metabolize it — become available.
The lipid produced by the HpnR protein may also be used as a biomarker in rock layers to identify dramatic changes in oxygen levels throughout Earth’s history.
“The thing that interests us is that this could be a window into the geologic past,” says MIT postdoc Paula Welander, who led the research. “In the geologic record, many millions of years ago, we see a number of mass extinction events where there is also evidence of oxygen depletion in the ocean. It’s at these key events, and immediately afterward, where we also see increases in all these biomarkers as well as indicators of climate disturbance. It seems to be part of a syndrome of warming, ocean deoxygenation and biotic extinction. The ultimate causes are unknown.”
The research was supported by the NASA Astrobiology Program via theNASA Postdoctoral Program, and was completed under the guidance ofNASA Exobiology and Astrobiology Institute Principle Investigator, Roger Summons, at the Massachusetts Institute of Technology (MIT).
The paper, “Discovery, taxonomic distribution, and phenotypic characterization of a gene required for 3-methylhopanoid production,” was published on July 23, 2012, in the Proceedings of the National Academy of Science (PNAS) under lead author Paula V. Welander.