FIG 2.

β-Galactosidase assays showing that induction of the pfeT gene is specific to iron. (A) WT cells containing a pfeT-lacZ transcriptional fusion were grown in LB medium amended with different metals, each at a specific concentration, to an OD₆₀₀ of 0.4. β-Galactosidase (β-Gal) activity was measured. Data represent means ± standard deviations for three or more biological replicates. Multipronged significance bars indicate statistical significance for a given condition in reference to results with LB medium, and significance was calculated using a one-way analysis of variance (ns, no statistical significance). Significance between results for the iron and normal LB conditions was calculated using an unpaired Student's t test (****, P < 0.0001). (B) β-Galactosidase assays to monitor pfeT-lacZ expression in LB medium amended with different concentrations of iron. WT cells show increasing levels of induction as a function of iron. Induction was even more sensitive to added iron when measured in pfeT::kan cells. As a control, the strain was also grown in LB medium containing the equivalent volume of 0.1 N HCl for each particular iron concentration. Results shown are representative of three biological replicates.