Эволюционная экология и стратегия выживания антарктических микроорганизмов в экстремальных условиях

Анотація

Aims. Microorganisms live in ecosystems of Antarctic in extreme conditions: low temperature, a high level of a solar radiation and the raised mineralization in coastal regions. In this connection ecophysiological properties of the bacteria isolated from soils, biofilms on rocks and phytocenosis of Antarctic have been studied. Methods. The aerobic microorganisms isolated earlier at 1-5ºС and 30ºС from various ecosystems of Antarctic have been studied. Resistance to UV radiation, psychro- and halotolerance have been defined by standard methods. Results. It is shown that Antarctic bacteria are presented: (1) psychrophilic and psychrotolerant bacteria (grow in a range 1-20°С or 1-30°С); (2) moderate halophiles (Halomonas sp. and Cryobacterium sp.), resistant to 10-15% NaCl; (3) UV-resistant bacteria. Strains Micrococcus sp. 3194, 3398, Methylobacterium sp. 3294, 3392 and Cryobacterium sp. 3179 were most resistant to UV (LD_99,99compounded210-360 J/m²). It is not revealed psychrophilic yeast from the same ecosystems, but all were psychro- and halotolerant (grew in a range 1-30°С and 10-15% NaCl). Pigmented strains of yeast (black and red) were highly resistant to UV (LD_99,99compounded 600-1200 J/m²), while for white yeast LD_99,99– 250 J/m². Conclusions. Strategy of a survival of microorganisms in Antarctic is directed on natural selection and sampling of microorganisms which initially were psychrotolerant and UV-resistant. If to take into consideration aerosol, ornithogenic and anthropogenic transfer of a microflora to Antarctic, the presented data allows to assume that the low temperature, high level UV, and also geographical isolation of islands are the primary cause for formation and evolution of microbic communities in Antarctic.

Key words: strategy of survival, antarctic bacteria/yeast, resistance to UV, psychrotolerance, halotolerance, evolution.