FIG 4.

Effects of loss of DPA on B. subtilis and C. difficile spore UV resistance. (A) Purified spores of strain PS832 (wild type) (●) and DPA-less spores of strains FB122 (spoVAF sleB) (▲) and PS3406 (spoVA sleB) (■) were irradiated with UV₂₂₂, and spore survival was determined as described in Materials and Methods. (B) Purified spores of C. difficile JIR8094, either the wild type (○ and ●), its dpaAB derivative (△ and ▲), or the complemented dpaAB derivative (□), were irradiated with UV₂₂₂ (○, △, and □) or UV₂₅₄ (● and ▲), and spore survival was determined as described in Materials and Methods. Data shown are averages from duplicate determinations ± standard deviations in one experiment. This experiment was repeated twice, and the same relative rates of killing of spores of different species/strains were seen.