A team led by scientists at the University of New South Wales has uncovered the genetic secrets of "extremophile" microbes that can survive in water temperatures as low as minus 20 degrees in the saltiest lake in Antarctica.
Deep Lake, about five kilometres from Davis Station, was formed about 3500 years ago, when the Antarctic continent rose, isolating a section of ocean. The water in the 36-metre deep lake is now so salty it remains in liquid form down to a temperature of minus 20 degrees.
"The lake has the distinction of being the least productive lake ever recorded, with very little able to grow in it," says Professor Rick Cavicchioli, of the UNSW School of Biotechnology and Biomolecular Sciences, and leader of the team.
The team took water samples from the lake at depths of five, 13, 24 and 36 metres, and studied the entire genetic sequence, or genome, of the microbes living there, to work out how they had evolved to cope with the extremely harsh conditions.
The results are published in the journal Proceedings of the National Academy of Sciences.
The extremophiles present belong to a group of microbes - haloarchaea – that are known to be "promiscuous", swapping DNA between themselves.
"But our research shows these ones swap much more genetic material with each other than has been observed in the natural environment before. Long stretches of virtually identical DNA are exchanged between different genera, not just species," says Professor Cavicchioli.
"Despite this rampant gene swapping, the different species are maintained and can co-exist because they have evolved to exploit different niches and consume different food sources."
Some, for example, consume proteins in the water; others consume sugars like glycerol, from algae living on the lake surface. It is estimated the haloarchaea grow very slowly in the lake, with only about six generations produced a year.
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