FIG. 3.

Mutation frequencies of outgrown spores and growing cells of different strains treated with H₂O₂. (A) Dormant spores of different strains were heat shocked and germinated, 0.2 mM H₂O₂ was added 15 min after the start of spore germination, aliquots were taken after 180 min of incubation, and frequencies of mutation to Rif^r were determined as described in Materials and Methods. (B) Overnight cultures of growing cells of different strains were inoculated into LB medium, 0.2 mM H₂O₂ was added, and after 180 min of growth frequencies of mutation to Rif^r were determined as described in Materials and Methods. The values are averages ± standard deviations for duplicate determinations in two separate experiments (with different cultures or lots of spores). WT, wild type.