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. As a result of the microbiological investigations it was shown that the total number of microbial cells have been in the same range of quantities as at the upper, younger horizons and varied from 1.3 x 10(2) up to 9.6 x 10(2) cl/ml. Some periodicity in the cell concentration and in their morphological diversity was revealed along the core. The maximal number and the greatest morphological variety were detected at horizons with the depth of 3534, 3555 and 3595 m. A drop in the cell concentration two or three times as much was found in ice layers under each of the above mentioned horizons. The discovered stratification is apparently connected with the periodicity of the lake water interactions with the basal ice layer and obviously depends on the complex natural events which took place in the geological history of our planet.

[Microbiological characterization of the accreted ice of subglacial Lake Vostok, Antarctica]. / Mikrobiologicheskaia kharakteristika akkretsionnogo l'da nad ozerom Vostok (Antarktida).

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.

[Dependence of the fatty acid composition of the lipids in fungi of the genus Penicillium on their natural habitat conditions]. / O zavisimosti zhirnokislotnogo sostava lipidov gribov roda Penicillium ot ikh prirodnykh uslovii obitaniia.

The fatty acid composition of lipids was studied in Penicillium fungi growing in different habitats. Saturated fatty acids were represented by lauric, margaric, stearic and palmitic acids (the latter prevailed-- 18%-26%). Unsaturated monoene fatty acids were represented by acids from C16:1 to C18:1, diene and triene fatty acids by linoleic and linolenic acids. The predominance of linoleic acid was not found in all cultures of the genus. Changes in the fatty acid composition of lipids may be attributed to different ecological habitats of the Penicillium genus species.

Microbiological flora as a function of ice depth in central Antarctica.

A technique has been developed for obtaining ice samples under sterile conditions for microbiological analyses as a function of ice thicknesses and with a view to clarifying the possibility of long term microbial anabiosis under permafrost conditions. For the first time microbiological studies from the surface down to 312 meters in the Vostok station region have been carried out and the distribution of microorganisms in the strata studied has been clarified. Microorganisms occur rather rarely, and their distribution is of a random character, independent of the depth of sampling. Viable microorganisms have been found in the ice horizons approximately as old as 8-13 thousand years.

Exobiology and the effect of physical factors on micro-organisms.

A study of the action of different physical factors on micro-organisms is necessary for a further development of exobiology. The action of temperature on crystalline preparations of catalase and peroxidase was studied by means of oscillographic polarography. A determination of the height of polarographic waves at the decrease of temperature from 20 degrees C to 0 degrees C has shown that structural elements of the peroxidase molecule connected with the enzymatic activity are more stable with the decrease of temperature cf. catalase. A relative resistance of the dehydrogenase activity in Az. vinelandii cells to high vacuum was found. Incubation of azotobacter cells under vacuum of 10(-9) mm Hg during 72 hr did not decrease the activity of alcohol and succinic dehydrogenase. Bac. cereus spores can be preserved from bactericidal UV action by thin films of chrome. The thickness of chrome film being 200-670 angstroms, spores are killed by a dose of 7.8 x 10(7) erg/cm2 at 253.7 microns wave length. Spores covered by chrome film thicker than 800 angstroms remain alive after this treatment. Investigations carried out with an 'Artificial Mars' camera led to the following results. The growth of Bac. megaterium on liquid growth media in this camera ceases as a result of UV rays killing all cells after 3 weeks. Untreated bacteria grow in the camera for a long time. Spore-forming bacteria isolated from the sand of the Kara-Kum Desert grow in ground limonite (with the addition of 2% garden soil) having maximum hygroscopic humidity (3.8%). Freezing and thawing (from -60 degrees C to +25 degrees C) corresponding to day temperature deviations on Mars, low pressure (P=10 mm Hg) and the composition of the atmosphere (CO2-50%, N2-40%, Ar-10%) do not influence the growth of xerophylic bacteria under study. Humidity is the main factor limiting the growth of micro-organisms under 'Artificial Mars' conditions. According to the further development of the microbiological meteorite analysis methods, samples of rocks and stone meteorites were sterilized, incubated in the desert or on a snow surface in the Arctic and after different times (from 100 days to 7 months), investigated. In all cases, microbes were found only on the sample surfaces, whereas 1 cm from the surface and in the central parts micro-organism were completely absent. Hence, microbiological analysis of central parts of meteorites fallen in the Arctic or during dry periods of the year in the desert can give reliable results.

The possibility of life in outer space.

Experiments were carried out dealing with the effect of extreme factors on microorganisms. Methods for microbiological analysis of meteorites were developed. The effect of temperature, from -20 degrees C to +15 degrees C, on trypsine activity was studied. It was shown that at about -3 degrees C a definite intramolecular reorganization occurs in the enzyme, leading to decreased activation energy. Previously reported resistance of microorganisms to high vacuum was confirmed. New species were tested at l0(-8)-10(-9) mm Hg. It was shown that very thin metal and metal oxide films, as well as films from other substances, may fully protect microorganisms from the hazardous effect of UV rays. By using an artificial climate, camera forms of microorganisms were selected which have the highest resistance to the whole complex of Martian climatic factors. Pigmented and spore-forming microorganisms resist UV up to a dose of 4.04 x 10(8) erg/cm2. There are microorganisms on Earth which show some activity in soil at a relative humidity of 0.096-0.196%. Preliminary data permit one to assume the possibility of existence of Earth-like forms on Mars. The majority of meteorites are accessible to Earth microorganisms. While choosing a meteorite for microbiological analysis it is necessary to consider the soil and climatic factors of the country where the latter has been found.