FIG. 2.
Resistance of α−β− spores overexpressing SspC, SspCΔ11, and SspCΔ11-D13K to UV radiation. Spores of various strains were purified, and their resistance to UV radiation at 254 nm was determined as described earlier (14) under conditions in which the spores were exposed to 45 J of UV radiation per m2 at 254 nm for 1 min. This experiment was performed twice with independent spore preparations. The relative resistances of the strains were the same in both experiments, with average D90 values (time to kill 90% of the initial spore population) of 30 s for α−β− spores, 3 min for SspCΔ11 spores, 8 min for SspCΔ11-D13K spores, and >20 min for SspC spores. Symbols: ■, α−β−SspC; ▵, α−β−SspCΔ11-D13K; ○, α−β−SspCΔ11; and □, α−β−pUB110.