Ancient microbes tough it out in Antarctic lake

Posted by Flora Malein

Scientists have discovered a group of microorganisms capable surviving one of the toughest environments on our planet: ancient bacteria living under 65 feet of ice at the bottom of a brine-filled lake in Antarctica. 

The fact that these bacteria are able to survive such extreme conditions - high salinity combined with the absence of sunlight and heat - supports the possibility that life could exist in similarly extreme conditions on other planets. The paper is published in the journal Proceedings of the National Academy of Sciences.
 
"This provides us with new boundary conditions on the limits for life," says Peter Doran, professor of earth and environmental sciences at the University of Illinois. "The low temperature or high salinity on their own are limiting, but combined with an absence of solar energy or any new inputs from the atmosphere, they make this a very tough place to make a living."
 
The team of researchers drilled deep into the permanently ice-covered Lake Vida to retrieve the ice cores for analysis. They also collected samples of the brine within the ice. They found that the ancient bacteria exist in a form of metabolic-soup made up of high levels of organic carbon and hydrogen.
 
Their findings were surprising, as they didn't expect anything to be able to survive in the dark, cold and salty ecosystem under the ice.
 
"Geochemical analyses suggest that chemical reactions between the brine and the underlying sediment generate nitrous oxide and molecular hydrogen," said another of the paper’s authors, Fabien  Kenig. 
"The hydrogen may provide some of the energy needed to support microbes."
 
"We'd like to go back and find if there is a proper body of brine without ice down there," adds Doran. "We'd also like to get some sediment cores from below that to better establish the history of the lake. In the meantime, we are using radar and other geophysical techniques to probe what lies beneath."