FIG. 4.

Growth of Lcr⁺ cells of Yersinia pestis strain KIM at 37°C in Ca²⁺-deficient chemically defined medium lacking added Na⁺ and l-glutamate (A), containing only 100 mM Na⁺ (B), containing only 25 mM l-glutamate (C), and containing both Na⁺ and l-glutamate (D) at an initial pH of 5.0 (•), 5.5 (○), 6.0 (▪), 6.5 (□), and 7.0 (▴). Dashed lines indicate the extent of growth in control cultures containing 4.0 mM Ca²⁺ at an initial pH of 7.0.