β-Galactosidase activities in P. aeruginosa strains containing chromosomal lacZ fusions to the fdx1 5' sequence. (A) Scheme of the two constructs used to monitor transcriptional activities of the fdx1 promoter. The -529 and -200 positions are relative to the +1 start of translation. (B) Relative β-galactosidase activities triggered by the constructs in (A) under normal conditions (white bars), for calcium depleted (for T3SS induction) cells (black bars), and for cells grown under semi-aerobic conditions with KNO3 (gray bars). (C) β-galactosidase activities were measured in pFdx1Z and pFdx1shortZ strains grown in LB medium at the indicated OD600. The reported activity values are the average of at least two independent experiments performed in duplicate or triplicate. Error bars indicate standard deviations.