FIG 1.

MMC treatment induces CMV formation in lysogenic S. aureus strains NRS and RN4220. Mitomycin C (MMC) was added at 100 ng/ml (A) or at the concentrations indicated (B) to log-phase cultures of bacterial strains NRS135 and RN4220, as well as their lysogenic variants NRS77^phage and RN4220^phage. After 4 h of incubation, the amounts of CMVs in the supernatants were measured using a fluorescent dye and were quantified in arbitrary units (AU). In our system, a value of 1,500 AU corresponds to a CMV preparation containing 250 μg protein/ml. The graphs show data from at least three independent experiments. Statistical analysis was carried out using the unpaired t test. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.