FIG 6.

Regulation of the basA promoter in TF-supplemented medium and in HS. A. baumannii ATCC 19606^T carrying any of the three PbasA fusions (pLPV1Z::PbasA or pLPV2Z::PbasA or pLPV3Z::PbasA) or the corresponding promoterless vector was grown overnight in LB broth, washed with saline, and inoculated (OD₆₀₀ of 0.1) in either M9-S medium supplemented with 2.5 mg/ml TF (TF) or in HS (HS). As a control, 100 μM FeCl₃ was added to TF (TF + 100 μM Fe) or HS (HS + 100 μM Fe) to saturate the TF iron binding capacity. Luminescence (A), β-galactosidase activity (B), and fluorescence emission (C) were recorded after a 4-h (A to C) or 6-h (D to F) incubation at 37°C. Gray and black histograms indicate the PbasA fusions and the corresponding promoterless vectors, respectively. Data are the means ± standard deviations from three independent experiments.