FIG 3 .

The cor mutant is not hypersusceptible to acid pH, nitric oxide, hypoxia, or hydrogen peroxide. (A) M. tuberculosis Erdman, the cor mutant, and the cor mutant complemented with cor were diluted into 7H9-ADN to an OD₆₀₀ of 0.05 at pH 5.5 or pH 5.5 plus sodium nitrite. Six days later, bacteria were diluted and plated and CFU enumerated after 3 weeks. (B) M. tuberculosis Erdman, the cor mutant, and the complemented strain (cor-comp) were grown to late log phase and resuspended to an OD₆₀₀ of 0.1, and bacteria were plated to generate a dense lawn. Sterile paper discs placed on the plate were impregnated with 10 µl plumbagin, plates were incubated for 3 weeks, and the zone of inhibition was measured. (C and D) M. tuberculosis Erdman (black circles) and the cor mutant (red squares) were grown in 17-ml test tubes in triplicate, and gradual hypoxia was generated following the Wayne model. At each time point, tubes were sacrificed and OD₆₀₀ (C) and CFU (D) were determined. Data represent the results of one of three similar experiments. Data represent means ± standard deviations (SD) for both panels.