FIG. 3.

Effect of fur on expression of the three major tol-oprL transcriptional units under aerobic conditions. β-Galactosidase activities are means ± standard deviations from triplicate cultures. Samples were taken after 20 h of cultivation in TSB-DC with EDDHA at 400 μg/ml (PAO, black bars; C6, gray bars) or 50 μM FeCl₃ (PAO, cross-hatched bars; C6, diagonal-hatched bars). The expression levels of each fusion in C6 were significantly different than in PAO in iron-rich medium (P < 0.01, analysis of variance).