ArcAB-dependant expression of ompW . ompW, ompD, ompC, arcB and arcA mRNA levels were measured by qRT-PCR in a (A) ∆arcA, (B) ∆arcB and (C) ∆arcA/pBAD-arcA and ∆arcB/pBAD-arcB. arcB and arcA were used as negative controls in (A) and (B), respectively. Exponentially growing cells were treated with H2O2 1.5 mM or NaOCl 530 μM for 20 min and transcript levels were measured. Genetically complemented cells were grown in the presence of arabinose 1 mM. Control cells received no treatment. 16S rRNA levels were used for normalization. Values represent the average of three independent experiments ± SD.