Figure 4. Bacterial growth.

The rates and extent of bacterial growth (A: EGD-e; C: Δlmo0641; E:Δlmo0641/pPL2lmo0641) were determined in iron-restricted MOPS-L media supplemented with Hb (panels A–C; open, gray and black symbols represent addition of 0.0, 0.02 and 2 uM Hb, respectively) or Hn (D, E; open, gray and black symbols represent addition of 0.0, 0.2 and 2 uM Hn, respectively), and in BHI broth (F). The bacteria were cultured in BHI broth overnight. In A–E they were then subcultured in MOPS-L to stationary phase, and at t = 0 subcultured again at 1% into MOPS-L containing different concentrations of Hb or Hn. In F, at t = 0 they were subcultured into BHI broth. The flasks were shaken at 37°C and absorbance at 600 nm (initially close to zero for all cultures) was monitored for 12–26 h (note different scales). Because of the slow growth of L. monocytogenes in iron-restricted minimal media, this graphic representation focuses on the comparison of the mutant strains at later times in the growth cycle.