Verkholiak N. Ecological significance of sulfate-reducing bacteria in the purification of the aquatic environment from pollutants

The paper clarifies the importance of microorganisms in the processes of the aquatic environment purification from pollutants. It is known from the literature about a significant role of sulfate-reducing bacteria in the purification of environment. A strain was isolated from Lviv wastewater as a potential pollutant destructor, which was identified as Desulfotomaculum sp. AR1. The effects of various abiotic factors on the growth and development of bacteria Desulfotomaculum sp. AR1 and D. desulfuricans Ya-11, in particular, organic compounds – pyrogallol, hydroquinone, toluene, xylene, p-aminobenzoic acid is studied, the ability to utilize these substances as the sole source of carbon and energy, respectively reducing their content in the contaminated environment, is shown. Positive effect of fumarate on biomass accumulation by bacteria during the growth in medium with aromatic hydrocarbons is shown. The best growth of the studied bacteria is found at the presence of aromatic compound, fumarate and sulfate ion in the medium. Studied bacteria are capable for growth at the presence of amino acids in the medium – leucine, isoleucine and valine, utilizing them as the sole carbon source. Studied bacteria may be used in the development of technologies of wastewater purification from nitrogen-containing organic compounds, particularly, valine, leucine and isoleucine, produced under the anaerobic conditions in the process of protein-containing substrates destruction. The ability of Desulfotomaculum sp. AR1 and D. desulfuricans Ya-11 bacteria to grow in media with different sulfate ion concentrations is studied, their ability to grow at SO42- concentrations that highly exceed highest permissible concentration (HPC) is shown. Effects of abiotic factors on the growth of studied bacteria and their sulfidogenic activity under different cultivation conditions is studied. Inhibitory effects of toluene, xylene and p-aminobenzoic acid on the sulfidogenic activity of Desulfotomaculum sp. AR1 and D. desulfuricans Ya-11 is found. Not considerable amount of hydrogen sulfide, which is in 7 times lower than in the control medium, is found at these conditions, which enables the regulation of toxic hydrogen sulfide content in the environment. The ability of bacteria to grow in the medium with sodium lactate or aromatic hydrocarbons under the influence of heavy metal ions is shown. Addition of Cr(VI) to the medium with sodium lactate or toluene inhibits Desulfotomaculum sp. AR1 growth. The most expressed inhibitory effect on biomass accumulation by Desulfotomaculum sp. AR1 and D. desulfuricans Ya-11 is found under the synergic influence of Cu2+ and Cd2+.