[Microbiological characterization of the accreted ice of subglacial Lake Vostok, Antarctica].

The accreted ice of subglacial Lake Vostok extends upward from the lake water level (a depth of 3750 m) to the bottom surface of the overlying Antarctic ice sheet. All of the accreted ice samples, taken from depths between 3541 and 3611 m, were found to contain pro- and eukaryotic microorganisms, whose number and diversity varied in different ice horizons and correlated, to a certain degree, with the occurrence of organic and inorganic impurities in a given horizon. Some biological objects found in the accreted lake ice, including bacteria, microalgae, and the pollen of higher plants, were morphologically similar to those found earlier in the glacier ice bulk. The others were not. It is suggested that the microorganisms found in the lake ice may come from different locations--the bottom layer of the glacier ice, the bedrock underlying the glacier, and the lake water.