ENVIRONMENTAL ASSESSMENT OF THE CONDITION CLEARED FROM OIL POLLUTION OF FOREST SOIL WITH APPLICATION OF MICROorganisms
The treatment efficiency of oil-contaminated soils with microbiological preparations was evaluated by phytotoxicity and enzymatic activity of the purified soil. Phytotoxicity was estimated by the germination energy and germination of cress seeds and morphometric parameters of plants: the length of the ground part and the length of roots. Evaluation of the biological activity of the soil after remediation was made according to the potential and actual cellulolytic and urease activity of the soil. In this work, the Trichoderma asperellum “TH-11” and Trichoderma koningii “TSL-06” strains capable of oil-oxidation and the hydrocarbon-oxidizing bacteria strains Bacillus subtilis “2sp” and Bacillus cereus “12M” were used in various combinations - monocultures, mixed cultures and consortiums, and mixed cultures and consortiums. It has been established that the oil content in the soil in concentrations up to 10 % has a phytotoxic effect on plants, so the germination energy of cress was 50 %, germination rate is 72.5 %. After the bioremediation of oil-contaminated soil, the viability and survival of plants increased by 50 % and 28 %, respectively. The use of microorganisms for bioremediation also had a positive effect on the morphometric parameters of plants. The study of the potential cellulolytic capacity of polluted soil showed that the intensity of microbiological processes in the soil is strongly suppressed, which results in a low rate of cellulose decomposition of less than 10 % compared to 98 % in the control variant. At the same time, actual cellulolytic activity was higher than potential. Thus, the destruction of cellulose using strains of B. cereus + T. koningii, B. subtilis, B. cereus + T. asperellum was 20 %, 91 % and 95 %, respectively, the control variant - 100 %. Urease activity was observed in all samples, while in native soil it turned out to be less pronounced, which may indicate activation of the processes of transformation of nitrogen-containing compounds and restoration of ecological balance after bioremediation. The following strains were recommended for the reclamation of soil from oil pollution with subsequent cultivation of plants for the creation of biological products for the following purposes: B. cereus + T. koningii, B. cereus + T. koningii, B. subtilis + T. koningii consortia and mixed culture B. subtilis. + B. cereus.