Mikrobiol. Z. 2015; 77(6):31-38.
doi: https://doi.org/10.15407/microbiolj77.06.031

Phylogenetic Analysis and Autecology of Spore-Forming Bacteria from Hypersaline Environments

Gladka G.V., Romanovskaya V.A., Tashyreva H.O., Tashyrev O.B.

Zabolotny Institute of Microbiology and Virology, NAS of Ukraine
154 Akad. Zabolotny Str., Kyiv, 03143, Ukraine

Multi-resistant to extreme factors spore-forming bacteria of Bacillus genus are isolated from hypersaline environments of the Crimea (Ukraine) and the Dead Sea (Israel). Phylogenetic analysis showed distinction of dominating extremophilic culturable species in studied regions. In Crimean environments they are B. mojavensis and B. simplex, in the Dead Sea ecosystem - B. subtilis subsp. spizizenii, B. subtilis subsp. subtilis, B. licheniformis and B. simplex. Isolates are simultaneously halotolerant and resistant to UV radiation. Strains isolated from the Dead Sea and the Crimea environments were resistant to UV: LD90 and LD9999 made 100 - 170 J/m2 and 750 - 1500 J/m2 respectively. Spores showed higher UV-resistance (LD9999 - 2500 J/m2) than the vegetative cells. However, the number of spores made 0.02 - 0.007 % of the whole cell population, and should not significantly affect the UV LD9999 value. Isolates of both environments were halotolerant in the range of 0.1 - 10 % NaCl and thermotolerant in the range of 20 - 50 °C, and didn t grow at 15 °C. Survival strategy of spore-forming bacteria from hypersaline environments under high UV radiation level can be performed by spore formation which minimize cell damage as well as efficient DNA-repair systems that remove damages.

Key words: hypersaline environments, Bacillus, phylogenetic analysis, UV-resistance, halotolerance.

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