Extremophile bacteria hint at possibility of life on other planets

Courtesy of the Desert Research Institute of Nevada.

2010 camp set up on the Antarctic Lake Vida allowing scientists to core the ice and retrieve subglacial brine and ice samples. Courtesy of the Desert Research Institute of Nevada

Lake Vida of Antarctica is home to some of the saltiest waters on the entire planet, but researchers recently found bacteria living under the cap of these ice covered waters. The subglacial environment of this lake is anoxic with an average temperature of -13 °C and 200 on the salinity scale. These waters are 2,000 times saltier than safe drinking water and nearly six times saltier than the Red Sea, one of the saltiest bodies of water on the planet. The lake is encapsulated by 800-970m of permafrost making for a very isolated environment. Despite the conditions, Lake Vida was found to house a phylogenetically diverse and metabolically active bacteria.

Though the exact species has not been determined as of yet, the observed microbes’ means of survival was analyzed. The waters contain high levels of reduced metals, ammonia, molecular hydrogen, organic carbon, oxidized nitrogen species, and sulfate. These elements alone would not be able to sustain an ecosystem for long if at all; however, it is estimated that Vida’s bacteria have persisted here for over 2,800 years. Researchers hypothesize this is because of the brine-rock reactions occurring, which release electron acceptors to allow the bacteria to get the energy needed to survive. The chemoheterotroph nature of these bacteria coupled with their slowed down metabolism caused by the icy environment has allowed them to survive through millenia.

The study of these bacteria and their relatives helps provide a better view of how life can exist in a myriad of environmental systems. Mars, Europa, and Enceladus are three extraterrestrial environments with terrain parallels to what was seen in Lake Vida giving hope of life beyond what Earth has seen. It is possible that under the icy encapsulations of these celestial bodies, life undiscovered may exist.

Reference:
Alison E. Murray, Fabien Kenig, Christian H. Fritsen, Christopher P. McKay, Kaelin M. Cawley, Ross Edwards, Emanuele Kuhn, Diane M. McKnight, Nathaniel E. Ostrom, Vivian Peng, Adrian Ponce, John C. Priscu, Vladimir Samarkin, Ashley T. Townsend, Protima Wagh, Seth A. Young, Pung To Yung, Peter T. Doran. 2012. Microbial life at -13 °C in the brine of an ice-sealed Antarctic lake. Proceedings of the National Academy of Sciences.
http://dx.doi.org/10.1073/pnas.1208607109

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