ISOLATION AND STUDY OF THE MAIN PROPERTIES OF ACIDOPHILIC CHEMOLITHOTROPHIC BACTERIA ISOLATED FROM THE WASTE DUMPS OF FUEL-ENERGY COMPLEX IN UKRAINE

Abstract

Pure cultures of the acidophilic chemolithotrophic bacteria that are mesophilic and moderately thermophilic, were isolated from the acidophilic aboriginal association of the microorganisms from the waste dumps by fuel-energy complex of Ukraine. Their basic biological and applied properties studied. The main differences of the studied strains in relation to energy substrates were noted. One group of bacteria, according their ability to oxidize a wide range of energy sources, in particular iron (II), was referred to Acidithiobacillus ferrooxidans. Another group of bacteria, according their ability to oxidize preferentially sulfur and its reduced compounds, was referred to Acidithiobacillus thiooxidans. All mesophilic strains regardless of the source of isolation were characterized by approximately the same growth ability and biomass accumulation. However, the intensity of oxidation of ferrous iron was different and did not depend on the amount of the biomass. A comparative analysis of obtained results has allowed considering that strains of A. ferro­oxidans Lv red 9 and A. ferrooxidans Lv black 37 have maximum oxidative activity. Their example shows the ability of adaptation to new substrates, using them as an additional source of microelements and energy. A high level of the isolated strains leaching activity has been established. Both adapted and unadapted strains were able to leach rare metals – gallium and germanium from waste products (65.0 and 78.0%, respectively). The efficiency of extraction of other metals such as copper, lead, zinc, nickel, and aluminum was slightly lower and depended on the origin of the substrate and on the properties of the strain. However, even this level of biological leaching is sufficient to reduce the toxicity of waste dumps. The obtained results allow concluding about the wide distribution of representatives of the Acidi­thiobacillus genus in the dumps of the fuel-energy complex, their biological diversity, and a possibility of their use in biotechnologies of metal leaching.