and metal ions affect the expression of the PerR regulon. (A) Relative transcript levels of dpr and metQIN after 10 μM H2O2 stimulating. (B) Expression of EGFP in strains SC-19 and ΔperR in the CDM supplemented with different metal ions. The cells were grown to mid-log phase in the basal CDM with 50 μM Zn2+ and 50 μM Fe2+ or Mn2+ and treated with or without 10 μM H2O2 4 times in every 15 min. The final mean fluorescence intensity (MFI) was calculated by each sample’s MFI deducting the MFI of negative control (no EGFP inserted SC-19).