[Endospore formation by Streptomyces avermitilis in submerged culture].

The capability of streptomycetes to form endospores during their life cycle was studied in submerged cultures of Streptomyces avermitilis. Submerged S. avermitilis spores were most intensely formed (1) during the culture development cycles on synthetic medium CP1 with glucose under phosphate limitation, and (2) in autolysing cell suspensions of high density obtained by tenfold concentration of a stationary-phase culture grown in a synthetic medium resuspended in phosphate buffer (pH 7.

Microflora in the basal strata at Antarctic ice core above the Vostok lake.

The microbiological investigations of the Antarctic ice core at the Vostok station become especially important in connection with the discovery of an subglacial lake in this region. This lake is considered by the world-wide scientific community to be an important object for searching for relict forms of life on the Earth and also as a model for solving a number of problems of exobiology--for instance for development of methods to penetrate into underice sea at Europe--Jupiter's satellite. For the first time the Antarctic ice core samples were taken from the horizons which correspond to the basal zone (3534-3541 m) and to the accreation ice zone (3555-3611 m) above the subglacial lake Vostok.

[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.