Response of the rhizosphere microbial community of phytoremediation plants to oil pollution and the application of biopreparations

The present study aims to evaluate microbiological activity in the rhizosphere of plants growing under oil pollution conditions and in the presence of biopreparations having a different spectrum of action. Common sunflower (Helianthus annuus L.) and crested wheatgrass (Agropyron cristatum L.) were selected as phytoremediation plants. The soil was treated with the hydrocarbon-oxidizing preparation “Lenoil” and two preparations of nonspecific action having a growth-stimulating effect: “Elena” and “Azolen”. A soil pollutant concentration of 4% was selected for conducting plant-based bioremediation. The study showed a slight increase in the total microbial count and the microscopic fungi count in the rhizosphere of plants due to pollution, while indicating a decrease in the count of amino-autotrophs and cellulolytics. The introduction of non-specific biopreparations into the soil promoted the growth of destructive microorganisms despite the fact that microorganisms in the preparations are not designed for soil detoxification and decontamination. Under the effect of biopreparations, the rhizosphere of sunflower and wheatgrass plants exhibited an increase or stabilization of microbiological activity, which may indicate their positive effect on microbiological processes occurring in contaminated soil. The rhizosphere of Agropyron cristatum L. plants generally provided a more favorable environment for the development of such groups of bacteria as amino-autotrophs, cellulolytics, micromycetes, and hydrocarbon-oxidizing bacteria. Of the studied variants of soil treatment with biopreparations for phytoremediation purposes, it is recommended to combine the application of the “Lenoil” biopreparation and the planting of phytoremediation plants in oil-contaminated soil.