Hydrogen peroxide-induced oxidative stress responses in Desulfovibrio vulgaris Hildenborough

Abstract

To understand how sulphate-reducing bacteria respond to oxidative stresses, the responses of Desulfovibrio vulgaris Hildenborough to H2O2-induced stresses were investigated with transcriptomic, proteomic and genetic approaches. H2O2 and induced chemical species (e.g. polysulfide, ROS) and redox potential shift increased the expressions of the genes involved in detoxification, thioredoxin-dependent reduction system, protein and DNA repair, and decreased those involved in sulfate reduction, lactate oxidation and protein synthesis. A gene coexpression network analysis revealed complicated network interactions among differentially expressed genes, and suggested possible importance of several hypothetical genes in H2O2 stress. Also, most of the genes in PerR and Fur regulons were highly induced, and the abundance of a Fur regulon protein increased. Mutant analysis suggested that PerR and Fur are functionally overlapped in response to stresses induced by H2O2 and reaction products, and the upregulation of thioredoxin-dependent reduction genes was independent of PerR or Fur. It appears that induction of those stress response genes could contribute to the increased resistance of deletion mutants to H2O2-induced stresses. In addition, a conceptual cellular model of D. vulgaris responses to H2O2 stress was constructed to illustrate that this bacterium may employ a complicated molecular mechanism to defend against the H2O2-induced stresses.