Protection from toxic and mutagenic effects of H2O2 by catalase induction in Salmonella typhimurium.

Demple and Halbrook (1983) have reported that pretreatment of E. coli with H2O2 induces protection against the toxic effects of subsequent treatment with H2O2, which cannot be attributable to catalase induction, but rather to inducible repair of oxidative DNA damage. Here we report that pretreatment of Salmonella typhimurium with small doses of H2O2 also renders them resistant to subsequent higher doses of H2O2. However, this induced protection against H2O2, both concerning survival and mutations, is proportional to the amount of induced catalase activity of the bacteria, which accelerates the breakdown of H2O2 in the medium, thus lowering the effective dose.