MICs of different antibiotics toward P. aeruginosa WT, parR and parS mutants, and complemented parR/Tn7-parRS+ straina

Medium and antibioticMIC (μg/ml) (mode) in:
WTparR mutantparS mutantparR/Tn7- parRS+ strain
Minimal medium with high Mg2+ (2 mM)
    Polymyxin B10.250.251
Minimal medium with high Mg2+ (2 mM) and supplemented with 4 μg/ml indolicidinc
    Polymyxin Bc80.1250.1258
Minimal medium with low Mg2+ (20 μM)
    Polymyxin B164416
  • a MICs were determined by serial 2-fold dilutions in BM2-glucose minimal medium with 2 mM Mg2+, unless indicated otherwise. The MIC represents the concentration at which no growth was visually observed after 24 h of incubation at 37°C. The values shown are the modes of 4 to 8 independent experiments.

  • b NT, not tested.

  • c The cultures used to inoculate the MIC plates were also grown in the presence of indolicidin.