Oxidative stress response of sulfate-reducing bacteria.

摘要

Using a threefold approach consisting of molecular biology, physiology and biochemistry techniques, oxidative stress responses of four strains of sulfate-reducing bacteria, Desulfovibrio vulgaris, Desulfovibrio desulfuricans DSM 642, Desulfovibrio desulfuricans DSM 6949 and Desulfomicrobium norvegicum were investigated, and an alkyl hydroperoxide reductase enzyme system from D. vulgaris was characterized.; Genes encoding AhpC and AhpF, two components of alkyl hydroperoxide reductase, were isolated and characterized from D. vulgaris. Analyses of the ahpC and ahpF sequences identified them as having important features of alkyl hydroperoxide reductases. Analyses of alkyl hydroperoxide reductase genes indicate constitutive expression of the two components in D. vulgaris, and a large physical distance between the genes suggests a long evolutionary presence in the D. vulgaris genome.; Physiological studies conducted on four strains of sulfate-reducing bacteria quantifying growth inhibition by, and tolerance to oxidative stress in the forms of cumene hydroperoxide, hydrogen peroxide and potassium chromate. Additionally, cell survival after exposure to oxidative stress was quantified by viability staining.; Biochemical investigations characterizing alkyl hydroperoxide activity were conducted using protein from D. vulgaris, and NADH-dependent reduction of cumene hydroperoxide and hydrogen peroxide were observed. The results of cumene hydroperoxide reduction assays using different conditions of substrates, temperature and pH, and enzyme kinetics calculations from those experiments support the hypothesis that D. vulgaris has a functional alkyl hydroperoxide system.; The results of these physiological and biochemical investigations are discussed in the greater context of oxidative stress defense strategies characterized in sulfate-reducing organisms to date. (Abstract shortened by UMI.)