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The purpose ofthe work was to study the regularities ofFe(III) compounds reduction under the conditions of limited aeration by the strain Citrobacterfreundii Ml-31.1/1, and to assess the role ofFe(II)-reducing bacteria (FRB) in iron compounds transformation in ecosystems. The following methods were used: cultivation of microorganisms under the conditions of limited aeration, colorimetric determination ofbiomass and Fe(III) and Fe(I) compounds concentra- tion, the potentiometric measuring ofpH and Eh, gas chromatography. Results: Thermody- namic calculations of microbial interaction with iron compounds were experimentally verified The regularities of Fe(III) and Fe(I) compounds transformation by the model strain Citro- bacterfreundii Ml-31.1/1, isolatedfrom the typical mid-latitude ecosystem -river sludge were obtained. The balance ofiron compounds redistribution in cells and in the extracellularfraction was established Conclusions: The results obtained are the basis to assume that non-specific interaction of microorganisms with iron may significantly influence transformation of iron. Thermodynamic prognosis allows to carry out targeted regulation of microbial metabolism.

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.

Microbial communities of the Ecuadorian Andes and volcano Tungurahua were shown to be super resistant to representative toxic metals. Maximum permissible concentrations of toxic metals were 100 ppm of Hg2+, 500 ppm of Co2+ and Ni2+, 1000 and 1500 ppm of Cr(VI), 10000 and 20000 ppm of Cu2+. The effect of metal concentration increasing on the biomass growth, CO2 and H2 synthesis was investigated. Two types of response of microbial communities on the increasing of toxic metals concentrations were discovered. The first type of response is the catastrophic inhibition of microbial growth. The second type of response is the absence of microbial growth inhibition at certain metal concentration gradient. The succession of qualitative structure of Ecuadorian microbial communities was shown for the first time. Bacteria, yeasts and finally fungi consistently dominate in the microbial community at the Cu2+ concentration raising. Microorganisms resistant to ultra-high concentrations of toxic metals (e.g., 3000 ... 20000 ppm of Cu2+) were isolated from Ecuadorian ecosystems. These microorganisms are able to accumulate toxic metals.

The widespread of Fe(III)-reducing microorganisms in natural ecosystems of Ecuador of La Favorita, Tungurahua volcano and Papallacta areas was experimentally proved. High efficiency of microbial precipitation of soluble iron compounds was also demonstrated. Obtained results indicate the potential ability of Fe(III)-reducing microorganisms to influence the formation of carbon and iron vector fluxes in ecosystems, as well as development of effective biotechnologies of water purification from iron compounds.

In this paper it was given the effect of p-nitrochlorobenzene (NCB) on the homeostasis quantitative parameters of cave clays microbial communities from Western Ukraine and Abkhazia (Mushkarova Yama, Kuybushevskaya) and soils of Ecuador tropical ecosystems. For these microbial communities were determined maximum permissible concentrations and types of responses on xenobiotic. Microbial communities of Mushkarova Yama cave clays and rainforest soils of Ecuador were characterized by the first type of response. Microbial communities of Kuybushevskaya clays and mountain jungles of Ecuador were characterized by the second type of response. Maximum permissible concentration of NCB for Mushkarova Yama was 200 mg/l, for the other studied microbial communities--300 mg/l. It was shown, that microbial communities were not only highly resistant to NCB but also interacted with it by destroying this xenobiotic and decreasing its concentration in 4 times.

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.

Enterobacter hormaechei and Brevibacterium antarcticum strains isolated from ornithogenic soils of Galindez Island (West Antarctica) were investigated for their resistance to Cu2+ cations and for their capacity to Cu2+ uptake from the environment. The studied strains are capable to grow in the concentration range of copper 100-1100 mg/l and to extract 11-75% of Cu2+ from the environment depending on cultivation parameters and copper output concentration in the culture medium.

Fifty (50) strains of Pseudomonas genus have been isolated from the samples of soil, moss and bottom sediments taken on the Galindes, Piterman and Deception Islands (Ukrainian Antarctic station Akademik Vernadsky). Characteristic of the above strains by 84 phenotype features and identification by means of the computer program permitted them to be referred to the species Pseudomonas fluorescens (biovar V.), P. putida (biovars A and B), P. veronii. The belonging of the strain 23 to the species P. veronii has been confirmed by the results of sequence of 16S rRNA. Being grown at low temperatures (4 degrees C) the strains of the above species are characterized by high antagonistic activity as to Gram-positive, Gram-negative bacteria, yeast and microscopic fungi. Cultivation of antagonists at 26 degrees C led to the sharp decrease or complete disappearance of the antagonistic effect.