Dissertation is devoted to investigation of microbial resistance and interaction with representative toxic metals: metal-oxidizer Cr(VI), metals with replacing action Ni2+, Co2+ and metals with combined negative effect Cu2+ and Hg2+. Theoretically possible ways of microbial interaction with representative toxic metals and relevant necessary conditions (pH, Eh) were determined based on thermodynamic prognosis for microbial interaction with toxic metals. Usage of high-potential metals - Hg2+, Cr(VI), Cu2+ as electron acceptors in microbial dissimilatory metabolism was shown to be theoretically possible. Growth of microorganisms at extremely high concentrations of representative toxic metals was theoretically grounded and confirmed in practice. Thus, microorganisms from natural environments grew at 1000-2000 ppm of Cr(VI) and 10000-30000 ppm of Cu2+. Distribution of metal resistant chemoorganotrophic microorganisms was shown for the first time in natural environments, different by geographic, physical-chemical and climatic features. Maximum permissible concentrations (MPC) of representative toxic metals for microorganisms were in range of 100-30000 ppm of Cu2+, 100-1500 ppm of Cr(VI), 50-1500 ppm of Ni2+, 50-500 ppm of Co2+ and 5-100 ppm of Hg2+. These concentrations overcome by several times the lethal ones (1-10 ppm of metal ions) for other chemoorganotrophic microorganisms. Metal resistant microorganisms were isolated from environments with high (more than 100 ppm) and low (less than 1 ppm) concentration of representative toxic metals. The range of microbial resistance to toxic metals was as follows: Cu2+> Cr(VI)> Ni2+> Co2+> Hg2+. Increasing the number of metals in the medium enhances their toxicity, which was shown on the example of microbial communities from soil of is. King George and clay of abyss "Kuibyshevska". Decreasing of microbial resistance by 2,0-3,3 times at simultaneous presence of several toxic metals was presumably caused by synergic action of toxic metals. However, microorganisms were resistant to simultaneous action of several toxic metals in ultra-high concentration (1020 and1300 ppm of metal ions). Microbial communities from soil of.is. King George and ridge Piryn were shown to have two types of response on increasing in concentration of toxic metal. Correlative type of response is inhibition of microbial growth correlatively with increasing in toxic metal concentration. Non-correlative type of response is absence of microbial growth inhibition in a certain concentration range of toxic metals. Non-correlative type of response evidences high microbial resistance to toxic metals. Isolation of metal resistant microorganisms is assumed to be the most effective at metal concentrations, where non-correlative type of response is observed. Based on the results, model of metal resistant microorganisms' distribution in natural environments was developed. According to the model, microorganisms form four zones of resistance to metals: low, medium, high and ultra-high resistance. Obviously, the number of microorganisms decreases while toxic metal concentration raises. However, each environment contains microorganisms resistant to high concentration of toxic metals. Out from 76 isolates from natural environments 91% was resistant to 100 ppm and higher of representative toxic metals, and 46% accumulated Cu2+ in biomass. The most resistant to metals microorganisms were Kocuria carniphila, Micrococcus luteus, Rhodococcus qingshengii, Candida tropicalis. Microbial interaction with toxic metals was investigated on example of C. tropicalis. The strain was capable to provide two opposite processes: immobilize Cu2+ by its accumulation in biomass (164±1,5 mg of Cu(II) in 1 g of absolutely dry mass) and mobilize CuO, CuCO3 (42±1,5 ppm of Cu2+) by lowering the value of pH. Results show wide distribution of metal resistant microorganisms in natural environments. Moreover, both theoretical and experimental results, collection of metal resistant microorganisms may be used for development of new biotechnologies of industrial wastewater treatment from toxic metals and metal extraction from depleted ores.
