Fig 3. PMS-mediated protection against norfloxacin is altered in the ΔsufABCDSE mutant.

The E. coli wt (BE1000), ΔiscUA (AG030) and ΔsufABCDSE (AG031) strains were grown to mid-log phase in LB and then diluted to inoculate 96-well microplate wells containing LB liquid medium (grey bars), LB medium supplemented with 1/16 of the MIC_PMS of each strain (white bars) (MIC_PMS were 140 μM for wt, 160 μM for ΔiscUA and 55 μM for ΔsufABCDSE), LB medium supplemented with norfloxacin (150 ng/mL) (hatched bars) and LB medium supplemented with both 1/16 of the MIC_PMS of each strain and norfloxacin (150 ng/mL) (black bars). Cultures were incubated 18 hours at 37°C with shaking. Plates were read for OD₆₀₀ in Tecan Infinite. The experiments were repeated at least three times. The means and standard deviations are shown. Asterisks represent the statistical significance calculated using the Bonferroni method (** p<0.01; * p<0.05; ns p>0.05).