FIG 6 .

RecA and the SOS response are critical to persistence only during recovery from ofloxacin treatment (OFL tx). (A) Ofloxacin persisters decreased >1,000-fold in the absence of RecA expression (dashed purple) relative to when RecA was expressed from 2 h pretreatment with ofloxacin through recovery (dashed blue). RecA induction on LB plates during recovery only (red) was sufficient to restore persisters to WT levels. (B) Ofloxacin persisters decreased 25-fold with LexA3 (blue) relative to the WT (black). LexA3 induction on LB plates only (red) maintained this reduced survival. We note that LexA3 induction only during recovery reduced the overall viability in both ofloxacin-treated and untreated samples, and this was accounted for by plotting the surviving fraction. Data are average values ± standard errors from at least three biological replicates. Numbers of CFU per milliliter for all samples and controls are provided in Fig. S7 in the supplemental material.