The microbiocenoses of chernozem, dark-kastanozem, and sod-podzolic soils are sensitive to the hexachlorobenzene influence. The number of ecologically functional groups of bacteria was reduced by 10-15% compared to the control in all three types of soil under experimental contamination with HCB dose of 10 maximum permissible concentrations (MPC). Under influence of the highest HCB dose (10 000 MPC) the microbial quantity was decreased by 50 – 90% of the control. Under the action of 10,000 MPC HCB, the rate of basal respiration decreased by 50, 47, and 36%, respectively, in chernozem, dark-kastanozem, and sod-podzolic soils. With the addition of glucose, the substrate-induced respiration activity increased, which indicated an increase in the physiological activity of microorganisms. At the highest level of pollution with 10,000 MPC, the rate of substrate-induced respiration decreased three times compared to the control in chernozem and dark-kastanozem soils, and 2.6 times in sod-podzolic soils. Bacterial cultures 46 and 47 were isolated from organochlorine wastes landfill to show resistance to HCB and the ability to decompose it. According to morphologycal properties, isolates # 46 and # 47 are aerobic gram-negative rods with sizes 0.4 × 2.1 μm and 0.3 × 2.1 μm, respectively. Aerobic, catalase-positive and oxidase-positive. Following biological properties were established: ability to alkalinize lactate and succinate, tyrosine arylamidase, pyrrolidone-arylamidase activities, inability to assimilate malonate, sodium citrate, glucose, lactose, trehalose and other sugars, inability to hydrogen sulfide production. Detection of such marker acids as 2-hydroxyhexadecanoic (C16:0 2OH) and 3-hydroxydecanoic (C10:0 3OH) in the fatty acid spectrum of both isolates # 46 and # 47 in the 2 – 5% range from the total fatty acids content confirmed its belonging to representatives of the genus Comamonas. Comamonas testosteroni is characterized by the content (2 – 7%) of 2-hydroxyhexadecanoic (C16:0 2OH), tetradecanoic (C14:0) (< 1%) acids. Phylogenetic analysis of the 16S rRNA sequence genes showed that isolate #47 is similar up to 98.05% to Comamonas testosteroni strain LMG 1800 (deposited reference strain in the GenBank database), and isolate #46 is related to Comamonas testosteroni LMG 1800 to 97.77%, to give reasons to attribute these two newly isolated strains belong to the species Comamonas testosteroni. The strains are registered in the Ukrainian Collection of Microorganisms under numbers UCM B-400 and B-401, deposited in the GenBank database under numbers MW861636 and MW861637. The ability to degrade this pesticide was studied. The ability of C.testosteroni UCM B-400, B-401 to decompose HCB was revealed, which is evidenced by this pesticide residual concentrations compared to the initial content in the culture liquid. After 7 days cultivation in a liquid LB medium with the HCB addition in the concentrations: 10, 20 and 50 mg/l, the corresponding decrease was for C.testosteroni UCM B-400 by 70.2%, 64.0%, 58.5 %, and for C.testosteroni UCM B-401 – 70.1%, 68.7%, 56.2%. The membrane lipid unsaturation index for C. testosteroni UСM B-400 and B-401 strains in pure culture control was 0.52 and 0.6, and under the influence with 20 mg/l HCB dose decreased to 0.36 and 0.56 respectively. The physiological reaction of C. testosteroni B-400 and B-401 to the HCB presence was higher compared to the control by the content of primary products of lipid peroxidation – diene conjugates in bacterial cells (at a dose of 20 mg/l of HCB in the B-400 strain, and in the B-401 strain – in all experimental variants). The content of secondary products – triene conjugates and tertiary products - Schiff bases were significantly lower than the toxic load of HCB, which indicates the activation of resistance mechanisms. In vegetation experiments with experimental soil contamination, it was shown that the introduction of culture liquid of the studied strains had a positive effect on the development of tomato plants, which was confirmed by an increase in all biometric indicators. In variants with HCB contamination with the subsequent introduction of bacterial culture liquid, an increase in resistance to Clavibacter michiganensis UCM As-629 was observed to 8 – 16 %. Resistance to Alternaria alternata UCM F-16866 in variants with bioaugmentation of uncontaminated soil was up to 32%. It was also observed that the resistance of tomato leaves in variants with bioaugmentation of HCB-contaminated soil also increased to 20 – 28%, compared to the contaminated control, without strains applying. In the field conditions as a result of the application of complex bioremediation of the remediator corn variety Olena and the strain C. testosteroni UCM B-400, the decrease in the HCB concentration in the soil was 82%, in the variant with the monoculture of C. testosteroni UCM B-400 – 70%, and the using phytoremediator resulted in a decrease to 27,3%.
