Components of antioxidant systems in the cells of aerotolerant sulfate-reducing bacteria of the genus <Emphasis Type="Italic">Desulfovibrio</Emphasis> (strains A2 and TomC) isolated from metal mining waste |
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| Authors: | A L Bryukhanov V A Korneeva T Yu Dinarieva O V Karnachuk A I Netrusov N V Pimenov |
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| Institution: | 1.Faculty of Biology,Lomonosov Moscow State University,Moscow,Russia;2.Winogradsky Institute of Microbiology, Research Center of Biotechnology,Russian Academy of Sciences,Moscow,Russia;3.Laboratory of Biochemistry and Molecular Biology,Tomsk State University,Tomsk,Russia |
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| Abstract: | Two strains of sulfate-reducing bacteria of the genus Desulfovibrio (A2 and TomC) isolated from metal mining waste were able to grow on agar Postgate C nutrient medium under microaerobic conditions. Since their growth in liquid nutrient medium was just slightly affected by 1% O2 (initial concentration in the gas phase) and 0.05–0.1 mM H2O2, these strains were relatively oxygen-tolerant. Only the presence of oxidants in high concentrations (5–10% О2 or 0.3–1.0 mM H2O2) resulted in practically complete inhibition of their growth. Strain A2 was more resistant to oxidative stresses than strain TomC. Activities of the key enzymes of antioxidant defense—superoxide dismutase (SOD), catalase, and peroxidase—were revealed in the cell-free extracts of strain A2 grown under strict anaerobic conditions. While strain TomC was found to possess no peroxidase activity, its catalase activity was much higher than that of strain A2 (36 and 2 U/mg protein, respectively). SOD activity of both strains was almost the same (5 U/mg protein). Sublethal H2O2 doses (concentration of 0.05–0.15 mM and exposure for 45–240 min) resulted in a drastic increase of catalase activity, especially in strain A2. Sublethal О2 doses (1–2% in the gas phase) had no significant effect on activities of the antioxidant enzymes of both strains. The cytochrome composition determined from the absolute absorption spectra of the whole cells of strains TomC and A2 revealed the presence of the c heme (438 and 831 pmol/mg protein) and the d heme (336 and 303 pmol/mg protein, respectively). The presence of the d heme indicated the presence of the bd heme–heme quinol oxidase, which together with the c heme may provide for the functioning of the electron transport segment of the antioxidant defensive system, which is responsible for aerotolerance of sulfate-reducing bacteria. |
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