Thermophilic Bacteria in Lake Vostok

24 May 2005 - Articles, Logistics, Water & Oceans, Ice & Snow

The diagram shows the possible dynamics of Lake Vostok's formation. Redrawn from Lamont-Doherty Earth Observatory.

Glaciers sometimes hide a lake under their thick layers of ice. And some of these lakes fascinate researchers, particularly because they may contain as yet unknown life forms. In the Antarctic, beneath the Vostok research station, such a lake, of gigantic proportions (a surface area of 14,000 km²), is whetting the appetite of researchers.

Researchers have already made some surprising discoveries even though they have not yet been able to collect samples of liquid water, as drilling has not yet entered the last few metres of ice (in order to preserve this extraordinary lake from accidental external contamination, for example by bacteria carried by chemicals used to prevent closure of the drill holes).

Most recently, in the autumn of 2004, an international research team from Russia, France and the USA studied the composition of the last 85 metres of a deep ice core (made up of refrozen ice containing water from the lake), sampled at a level 130 m above the liquid interface with the lake. Analysis revealed that the biological content of Lake Vostok seems very limited, and that its waters are virtually sterilised by dissolved oxygen (at a pressure equivalent to that of a fizzy drink can) which accumulated after the ice's thawing. In addition, traces of DNA discovered in the refrozen ice has suggested the genetic signature of thermophilic bacteria! Such bacteria are better adapted to very hot environments, like those near hot undersea springs or volcanic chimneys, rather than to cold environments. Yet another mystery to be solved ...