Fig. 3.

Growth curves of Y. pestis CO92 WT and its Δcaf mutant. The bacilli were grown at 37°C in HIB medium with 2.5 mM CaCl₂. Samples were taken at 1-h intervals until the cultures reached their saturation phases. The OD₆₀₀s of the samples at different time points were recorded (A), and their actual counts (in CFU) (B) were determined by plating (40).