The study was published Monday, Nov. 26, in the scientific journal, Proceedings of the National Academy of Science (PNAS). Co-authors are MSU professor John Priscu and Christian Fritsen, a Corvallis native who was a postdoctoral researcher with Priscu during the 1990s. First author of the paper was Alison Murray at Nevada's Desert Research Institute (DRI).
Fritsen was an MSU undergraduate student from 1984 through 1988 and a postdoctoral researcher at MSU from 1995 through 1998. He is now a research professor at the DRI. Priscu, now in Antarctica for another field season, is a professor in the Department of Land Resources and Environmental Sciences in MSU's College of Agriculture. He has been studying polar ecosystems for the past 30 years.
The bacterial community described in the PNAS paper was found in Lake Vida, the largest of several unique lakes found in the McMurdo Dry Valleys. The lake contains no oxygen, is mostly frozen and possesses the highest nitrous oxide levels of any natural water body on Earth. A briny liquid that is approximately six times saltier than seawater percolates throughout the icy environment that has an average temperature of 8 degrees Fahrenheit.
"This study expands our knowledge of known habitats for life on Earth," Priscu said. "We are just beginning to unravel the lost world beneath our planet's ice sheets, and the survival strategies discovered in Lake Vida provide us with a unique window into the sub-ice cryosphere."
Despite the very cold, dark and isolated nature of the habitat, the report finds that the brine harbors a surprisingly diverse and abundant assemblage of bacteria that survive without a present-day source of energy from the sun. Previous studies of Lake Vida dating back to 1995 indicate that the brine and its inhabitants have been isolated from outside influences for more than 3,000 years.
Murray and her co-authors and collaborators, including the project's principal investigator, Peter Doran of the University of Illinois at Chicago, developed stringent protocols and specialized equipment for their 2005 and 2010 field campaigns to sample the lake brine while avoiding contaminating the pristine ecosystem.
To sample the unique environment, researchers worked under secure, sterile tents on the lake's surface to keep the site and equipment clean as they drilled ice cores, collected samples of the salty brine residing in the lake ice and then assessed the chemical qualities of the water and its potential for harboring and sustaining life, in addition to describing the diversity of the organisms detected.
Geochemical analyses suggest that chemical reactions between the brine and the underlying iron-rich sediments generate nitrous oxide and molecular hydrogen. The latter, in part, may provide the energy needed to support the brine's diverse microbial life.
"It's plausible that a life-supporting energy source exists solely from the chemical reaction between anoxic salt water and the rock," explained Fritsen, a systems microbial ecologist and research professor in DRI's Division of Earth and Ecosystem Sciences.
Murray said, "If that's the case, this gives us an entirely new framework for thinking of how life can be supported in cryoecosystems on earth and in other icy worlds of the universe."
Murray added that further research is under way to analyze the abiotic, chemical interactions between the Lake Vida brine and the sediment, in addition to investigating the microbial community by using different genome sequencing approaches. The results could help explain the potential for life in other salty, cryogenic environments beyond Earth.
The Lake Vida brine also represents a cryoecosystem that is a suitable and accessible analog for the soils, sediments, wetlands, and lakes underlying the Antarctic ice sheet that is the topic of two other projects in the Priscu Laboratory funded by NASA and the National Science Foundation.
Fritsen noted that he sees many similarities between the Lake Vida work and a U.S. drilling project planned for later this season in Antarctic's Lake Vostok. Both projects need to keep the environment clean while drilling. Both are entering environments that haven't been sampled before.
Funding for the Lake Vida research was supported jointly by the NSF and NASA.
The Desert Research Institute is the nonprofit research campus of the Nevada System of Higher Education.
For more information on the Lake Vida project, go to http://www.dri.edu/lake-vida
Evelyn Boswell, (406) 994-5135 or firstname.lastname@example.org