BIOREMEDIATION OF SOIL CONTAMINATED WITH SYNTHETIC COMPOUNDS
The efficiency of using bacteria of the Rhodococcus wratislaviensis KT112-7 strain and the humic fertilizer "Gumikom" for bioremediation of soil contaminated with synthetic compounds has been investigated. Due to the activities of the chemical industry, to date, there has been an accumulation in the environment of xenobiotics, resistant to microbial decomposition, dangerous to human health. Therefore, to prevent the negative consequences of this pollution, it is necessary to develop methods for cleaning the environment from a complex of synthetic pollutants. The technogenic soil used in the experiment was taken from the territory of the former chemical enterprise "Sredne-Volzhsky Chemical Plant" in Chapayevsk, Samara Region. The soil contained the following xenobiotics: hexachlorobenzene, lindane, a mixture of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloromethylmethane (DDT) and dichlorodiphenyltrichloromethylmethane (DDD), trialate, phthalic esters (dioctyl phthalate and dibutyl phthalate). Cells of bacteria of the R. wratislaviensis KT112-7 strain in the amount of 10<sup>7</sup> cells/g and the fertilizer "Gumikom" - 0.01, 0,1 and 1,0% were introduced into the soil, depending on the variant of the experiment, and after 2 weeks the content of residual pollutants. The concentration of xenobiotics was estimated using an Agilent 6890/5973N gas chromatography-mass spectrometer. Previously, the effect of humic fertilizer on the destruction of pesticides by bacteria-destructors in the soil has not been studied. The introduction of the "Gumikom" in doses of 0,1 and 1,0% reduced the concentration of trialate and phthalic acid esters in the contaminated soil relative to the variant without the addition of the humic fertilizer. The inoculation with R. wratislaviensis KT112-7 bacteria into the contaminated soil, compared with the option without the addition of destructive bacteria, reduced the concentration of lindane, a mixture of PCBs, DDT and DDD, triallate, phthalic acid esters. The maximum loss of most of the pollutants was observed when the drug "Gumikom" was added together with bacteria-destructors. With the introduction of "Gumikom" in doses of 0,1 and 1,0%, the greatest positive effect was observed on a decrease in the content of lindane, by 2,6 and 3,5, respectively, the least - on a decrease in the concentration of DDT and DDD - by 1,2 times. The data obtained can be used to develop biotechnologies for cleaning the environment from complex soil contamination with the studied xenobiotics.