A group of researchers from NASA have uncovered an ancient community of bacteria in one of the most remote lakes of Antarctica, nearly 65 feet beneath the icy surface. The group of scientists includes researchers from the Desert Research Institute (DRI) in Reno, Nevada, the University of Illinois in Chicago and nine other institutions.
According to the researchers, the finding of life existing in the darkest, saltiest and coldest habitats of Earth is important because it helps them know how life can sustain itself in extreme environments on the Earth and beyond.
Lake Vida, a hyper saline lake in Victoria Valley, is one of the largest lakes found in the McMurdo Dry Valley, on the continent of Antarctica. The lake contains no oxygen, is mostly frozen and also contains the highest nitrous oxide levels of any natural water body on the Earth.
A briny liquid, which is approximately six times saltier than seawater, percolates throughout the icy environment where the average temperature is minus 8 degrees Fahrenheit.
"This study provides a window into one of the most unique ecosystems on Earth. Our knowledge of geochemical and microbial processes in lightless icy environments, especially at subzero temperatures, has been mostly unknown up until now," said Alison Murray, a molecular microbial ecologist and polar researcher at the DRI.
Murray is also the lead author of the report that was published online Nov. 26 in the Proceedings of the National Academy of Sciences Early Edition.
"This work expands our understanding of the types of life that can survive in these isolated, cryoecosystems and how different strategies may be used to exist in such challenging environments," said Murray.
The report finds that despite the very cold, dark and isolated nature of the habitat, the saltwater harbors a surprisingly diverse and abundant variety of bacteria that survive without a current source of energy from the Sun.
Previous studies of Lake Vida dating back to 1996 indicate the saltwater and its inhabitants have been isolated from outside influences for more than 3,000 years.
"This system is probably the best analog we have for possible ecosystems in the subsurface waters of Saturn's moon Enceladus and Jupiter's moon Europa," said Chris McKay, a senior scientist and co-author of the paper at NASA's Ames Research Center, Moffett Field, Calif.
Researchers had developed stringent protocols and specialized equipment for their 2005 and 2010 field campaigns to sample from the lake brine while avoiding contaminating the pristine ecosystem.
"The microbial ecosystem discovered at Lake Vida expands our knowledge of environmental limits for life and helps define new niches of habitability," said Adrian Ponce, co-author from NASA's Jet Propulsion Laboratory, Pasadena, California, who enumerated viable bacterial spore populations extracted from Lake Vida.
Geochemical analyses suggest that chemical reactions between the saltwater 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.
Additional research is underway to analyze the abiotic, chemical interactions between the Lake Vida brine and its sediment, in addition to investigating the microbial community by using different genome sequencing approaches, NASA said.
Researchers believe that the results could help explain the potential for life in other salty and low temperature environments beyond the Earth, such as purported subsurface aquifers on Mars.
