[Diversity and Physiological and Biochemical Properties of Heterotrophic Bacteria. Isolated from Lake Baikal Neuston.]

For heterotrophic microorganisms (44 strains) isolated-from the surface film of Lake Baikal, iden- tification was carried out and their. physiological and biochemical characteristics were determined. Com- pared to the water column, diversity of cultured heterotrophs was low, indicating formation of stable micro- bial communities at the air-water interphase interface. Heterotrophic bacteria isolated from the surface mi- crolayer exhibited the enzymatic activity comparable to that for strains form other biofilm associations. Deinococcusfi6us strain NA202 'vas the most active component of the community, capable of utilization of the broadest spectrum of mono- and disaccharides,'sugars, and amino acids. This strain possessed the highest diversity of extracellular enzymes and was the most resistant to UV radiation. The physiological and bio- chemical properties of this strain may-be responsible for its adaptation to survival in extreme conditions of the surface microlayer. Our results improve our understanding of occurrence of UV-resistant strains in freshwater ecosystems.

[Resistance to Dehydratation of Extremophilic Bacteria from Antarctic Region and Hypersaline Reservoirs].

Purpose: To determine resistance to dehydratation of bacteria resistant to UV irradiation. Methods: Objects of research - extremophilic bacteria (from Antarctic islands and hypersaline reservoirs of Israel and Crimea). Dehydratation of bacteria was carried out in sealed desiccator; the exposure without access of moisture was 5 weeks, temperature - 22 - 25 °C, humidity - 1 - 4 %. UV irradiation of bacteria was carried out by lamp BUF 15 (A = 254 nm) in the range of 40 - 2400 J/m(2). After cultivation irradiated and not irradiated strains (before and after UV irradiation and before and after drying) we determined the number of cells. Results: The extremely resistant to dehydratation (Firmicutes) and extremely sensitive to dehydratation (Proteobacteria, Bacteroidetes) strains was found among the studied bacteria. Most strains of bacteria that were resistant to dehydratation were also resistant to UV irradiation. Survival after dehydratation in these bacteria was 6.32 - 55.26 % and UV LD99.99 240-600 J/m(2). Instead, representatives of Proteobacteria were extremely sensitive to these extreme factors: the cell survival was 0 - 1.6 % after dehydratation and UV LD99.99 80 - 180 J/m(2). Conclusions: The results support the hypothesis that between bacteria resistance to electromagnetic radiation (UV) and their resistance to dehydratation there is a correlation.

PHYLOGENETIC ANALYSIS AND AUTECOLOGY OF SPORE-FORMING BACTERIA FROM HYPERSALINE ENVIRONMENTS.

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 LD99.99 made 100-170 J/m2 and 750-1500 J/m2 respectively. Spores showed higher UV-resistance (LD99.99-2500 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 LD99.99 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.

Autecology of microorganisms of typical Ecuador biotopes.

34 strains of aerobic chemoorganotrophic microorganisms were isolated from 23 soil and plant samples selected from highland biotopes of Ecuador-Andes massif (Papallacta, 4020 m), ash at the foot of the volcano Tungurahua, mountainous jungle (La Favorita, 1600 m), as well as in humid tropic botanical garden (state Puyo, 950 m). In mountain jungle samples the high number of bacteria--10(5)-10(7) CFU/g of sample were represented by 2-5 morphotypes. In highland (4020 m) samples the bacterial counts made from 10(2) to 10(7) CFU/g of sample. The current study describes resistance of isolated strains to high salinity, UV radiation and toxic metal ions. The majority of isolated strains were halotolerant. Isolates from volcanic ash showed high resistance level to UV radiation--LD99,99 made 1000-1440 J/m2; resistance level for isolates from the soil of Puyo Botanical Garden and isolates from rock lichen (Papallacta) LD99,99 made 1160 and 800 J/m2 respectively. Strains isolated from mountain jungle (La Favorita) showed lower UV-resistance. In highland biotopes of Ecuador occurred bacteria resistant to toxic metal ions. The highest resistance to Hg2+ was shown by isolate of lichen from mountain jungle, the maximal growth concentration was 0.025 g/L; to Cr(VI)--by isolate from lichen rock massif--3,0 g/L. Correlation between metal-resistance, halotolerace and UV resistance for studied strains was not detected, probably because of different microbial cell damage/repair mechanisms under the action of these factors.

[Resistance of Antarctic microorganisms to UV radiation].

The paper deals with the samples of microorganisms isolated from biofilms of encrustation of 11 stationary points of monitoring on the vertical rock of biogeographical testing ground (island Galindez, Antarctic Region). They are presented by morphologically various forms of bacteria (n x 10(7) cells in 1g of sample), yeast (n x 10(5)) and fungi (n x 10(4)-10(6)). Threshold and lethal UV dozes for isolated monocultures of the Antarctic microorganisms are determined. The threshold doze of UV radiation which is a measure of ability of a cell to reparation of DNA damages for bacteria was 40-70 J/m2. The lethal UV doze (LD99.99) for bacteria varied within the limits of 200-480 J/m2, for yeast of 700-1200 J/m2. Both pigmented and not pigmented bacteria were resistant to UV radiation. As a rule, Gram-positive bacteria were more resistant to UV than Gram-negative ones. It is shown, that resistance of investigated Antarctic rocky microorganisms to UV radiation is their genetically stable characteristic.

Screening for restriction endonucleases in methane-oxidizing bacteria.

51 methane-oxidizing bacteria strains such as Methylomonas methanica, M. rubra, Methylococcus capsulatus, M. thermophilus, M. luteus, M. ucrainicus, M. whittenburyi, Methylosinus trichosporium, M. sporium, Methylocystis parvus isolated from various ecological niches and geographical regions of the Ukraine and also the strains received from R. Whittenbury and Y. Heyer were screened for restriction endonucleases. Type II restriction endonucleases were detected in IMV B-3112 (= 12 b), IMV B-3027 (= 26), IMV B-3019 (= 9 c), IMV B-3017 (= 17 c), IMV B-3226 (= 26 v), IMV B-3033 (= Y), IMV B-3100 (= 100) and IMV B-3494 (= 1E494). The results obtained were indicative of relatively high frequency of restriction enzymes occurrence in methane-oxidizing bacteria. There were Kpn I (Asp 7181) restriction endonuclease isoschizomers in crude extracts of IMV B-3112, B-3017, B-3019, B-3027 isolated from fresh-water silt as well as in IMV B-3226 strain isolated from waste-water silt. Although these isolates had bee previously considered as untypical strains of M. ucrainicus, more detailed study of their properties allowed placing them with Methylovarius luteus (= Methylococcus luteus). IMV B-3494 strain was identified as Methylococcus capsulatus. Strain IMV B-3033 had earlier been allocated to Methylovarius whittenburyi (= Methylococcus whittenburyi). Specificity of restriction endonucleases of this strain was not tested. Therefore, for the first time restriction endonucleases were detected in methane-oxidizing bacteria. 8 strains (3 species) among 51 strains (13 species) were found to produce restriction endonucleases displaying three different types of specificity in the least. Producers of restriction endonucleases having Kpn I (Asp 7181) specificity were isolated from different water and silt samples of the Dnieper flood-land more than 20 years ago.