Abstract
The usage of microorganisms to clean the environment from xenobiotics, in particular chlorine-containing ones, is a promising method of detoxifying the contaminated environment. Sulfate-reducing bacteria Desulfovibrio desulfuricans Ya-11, isolated from Yavoriv Lake, and Desulfotomaculum AR1, isolated from the Lviv sewage treatment system, are able to grow under conditions of environmental contamination by aromatic compounds and chlorine-containing substances. Due to their high redox potential, chlorate and perchlorate ions can be ideal electron acceptors for the metabolism of microorganisms. To test the growth of the tested microorganisms under the influence of perchlorate ions, bacteria were cultured in modified Postgate C medium with ClO4–. Biomass was determined turbidimetrically, the content of sulfate ions and hydrogen sulfide – photoelectrocolorimetrically, the content of perchlorate ions – permanganatometrically. The study of the ability of sulfate-reducing bacteria Desulfotomaculum AR1 and D. desulfuricans Ya-11 to grow in a medium with perchlorate ions as electron acceptors showed the inhibitory effect of ClO4– on sulfate ion reduction by bacteria. Bacteria Desulfotomaculum AR1 and D. desulfuricans Ya-11 are able to grow in environments with aromatic hydrocarbons, in particular toluene. The possibility of the growth of sulfate-reducing bacteria in the presence of toluene as an electron donor and perchlorate ions as an electron acceptor was investigated. The efficiency of perchlorate ion utilization by sulfate-reducing bacteria Desulfotomaculum AR1 and D. desulfuricans Ya-11 was about 90 %. The effect of molybdenum on the reduction of perchlorate ions by Desulfotomaculum AR1 is shown in the paper. Immobilization of bacteria Desulfotomaculum AR1 and D. desulfuricans Ya-11 was carried out in 3% agar and on wood chips. The ability of bacteria, immobilized on these media, to purify the aqueous medium from perchlorate ions was investigated. Reduction of perchlorate ions is more efficiently performed by cells of Desulfotomaculum AR1 and D. desulfuricans Ya-11 bacteria immobilized in agar than on wood chips. Sulfate-reducing bacteria Desulfotomaculum AR1 and D. desulfuricans Ya-11 are able to use perchlorate ions as electron acceptors, purifying the polluted aquatic environment from these pollutants.
Highlights
Problems of environment and food pollution by perchlorate ions are of worldwide relevance (Aribi et al, 2006)
We have studied the ability of sulfate-reducing bacteria Desulfotоmaculum AR1 and D. desulfuricans Ya-11 to grow in medium with perchlorate ion as electron acceptor
Effectiveness of sulfate ion reduction by the studied bacteria is significantly high in control medium – approximately 60% in both bacterial strains, whereas it is 49% in Desulfotоmaculum AR1 and 46% in D. desulfuricans Ya-11 at the presence of perchlorate ion (Table 1)
Summary
Problems of environment and food pollution by perchlorate ions are of worldwide relevance (Aribi et al, 2006). Presence of perchlorate ions in water supplement systems and soil is connected with the widespread usage of fertilizers, Chile saltpetre (Urbansky et al, 2001). Perchlorate ions’ content in the water of centralized drinking water supply systems must not exceed 0.01 mg/dm, according to DSTU 7525 from the year 2014. Perchlorate ions are found in food, besides soil and the water environment (El Aribi et al, 2006). Perchlorate ions have a toxic effect on the human organism. Perchlorate ions competitively block iodine uptake by the thyroid gland and inhibit production of hormones, which can result in metabolic problems in adults and abnormal growth of children (Greer et al, 2002)
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