THE INDUCTION OF OXIDATIVE-ENZYMES IN STREPTOMYCES-COELICOLOR UPON HYDROGEN-PEROXIDE TREATMENT

Streptomyces coelicolor (Mulier) became resistant to killing by hydrogen peroxide (H2O2) when pretreated with non-lethal concentrations of H2O2. When rapidly growing cells were pretreated with 100 muM-H2O2, they became 7-10-fold more resistant to 20 mm-H2O2 than were naive cells. Activities of several oxidative defense enzymes were measured in cells treated with 100 muM-H2O2 in either exponential or stationary phase growth. The specific activity of catalase in crude extracts of cells pretreated in either phase increased about 40%. Peroxidase activity, in cell extracts and culture supernatants, respectively, of cells treated in the stationary growth phase increased two times and four times. Glucose-6-phosphate dehydrogenase increased by 60 % at the exponential growth phase. Glutathione reductase increased 80 % after treatment in the exponential phase and 4-fold in the stationary growth phase. However, superoxide dismutase activity decreased by 70%. Two mutants resistant to H2O2 were isolated after mutagenesis of spores with N-methyl-N'-nitro-N-nitrosoguanidine. In addition to a dramatic increase in the survival rate in 20 mm-H2O2, both mutants exhibited increased activities of all the above enzymes except superoxide dismutase. The pleiotropic phenotype of the mutants suggests that there exists a global regulation of oxidative response in S. coelicolor.