Survival of Halobacterium NRC-1 wild-type and putative photolyase mutants following UV-C irradiation. (A) Wild-type Halobacterium NRC-1 survival (N/No; x-axis) in light following increasing doses of UV irradiation (J/m²; y-axis). (B) Survival of single (phr1 or phr2) and double (phr1/phr2) knockout mutants on recovery in light (gray bars) and dark (black bars) post-UV irradiation at 200 J/m². Relative difference in effects of UV-C irradiation at 100 and 200 J/m² on viability of the wild-type organism is shown. (N) Number of viable cells in challenged sample; (No) number of viable cells in control; error bars represent standard error for at least three independent experiments.