The resistance of chernozem soil microorganisms to soluble copper compounds

Аim. Determination of resistance of Ukrainian chernozem soil microorganisms to the influence of toxic copper(II). Methods. Content of copper-resistant microorganisms in chernozem was determined by counting colonies on a solid nutrient medium containing Cu(II). Resistance of microorganisms was determined by cultivation in the medium with concentration gradient of Сu2+. Results. Microorganisms resistant to toxic copper(II) by ultrahigh concentrations were shown to be present in chernozem soil. Microorganisms grew in the medium containing up to 500 mg/l Cu2+ (CuSO4 solution) and up to 10000 mg/l Cu2+ (in complex with citrate). Chelation of copper(II) with citrate was found to lead to increase of microbial resistance in 20 times. It was determined that a vanishingly small number of microorganisms resistant to toxic copper by ultrahigh concentrations can exist in a natural ecosystem. The number of viable microorganisms decreases with the increase in the content of Cu2+ that is described by the hyperbolic curve. Conclusions. The proposed methodological approach not only allows to isolate copper-resistant microorganisms from natural ecosystems of all geographic zones of the globe, but also avoid complex genetic transformations in order to obtain perspective genetically modified strains for further application in biotechnologies for purification of industrial wastewater. Keywords: copperresistant microorganisms, chernozem soil of Ukraine, diversified microbial community, environmental biotechnologies.