DNA repair sensitivity of exponential-phase ΔsbcC and ΔykoV mutants to the killing action of MMC. The strains used are indicated by the relevant genotype. Serial dilutions of a culture of each strain were plated in selective medium containing the indicated concentration of MMC. Wild type cells were exposed to 150 ng/ml, ΔsbcC, ΔykoV or ΔsbcC ΔykoV to 125 ng/ml, ΔrecN, ΔsbcC ΔrecN or ΔykoV ΔrecN to 40 ng/ml and ΔrecA, ΔykoV ΔrecA or ΔsbcC ΔrecA were exposed to 3 ng/ml of MMC. At least three independent experiments were performed and one of them is presented.