Fig 1. Growth of wild-type M. tuberculosis and of the ΔmbtD mutant with different iron sources.

Growth of wild-type Mtb mc²6230 (A) and the ΔmbtD::hyg^r mutant (B) in self-made low-iron 7H9 medium supplemented with: 20 μM ammonium ferric citrate; 10 μM human holo-transferrin; 10 μM human holo-lactoferrin; 5 μM human hemoglobin; 20 μM hemin; 0.2 μM mycobactin (MBT) and 0.2 μM carboxymycobactin (cMBT), respectively. The Mtb strains were grown in self-made low-iron 7H9 medium for 5 days to deplete intracellular iron before growth analysis. The initial OD₆₀₀ of all the cultures was 0.01. Error bars represent standard deviations from the mean results of biological triplicates.