FIG. 3.

Growth of Yersinia pestis strain KIM at 37°C in Ca²⁺-deficient chemically defined medium containing (A) constant l-glutamate (25 mM) and 100 mM Na⁺ (○), Li⁺ (▵), K⁺ (□), or Tris⁺ (▿); a parallel control culture containing Na⁺ and Ca²⁺ (4.0 mM) is included (•). Also shown (B) is growth of Y pestis strain KIM at 37°C in Ca²⁺-deficient chemically defined medium containing constant Na⁺ (100 mM) and 25 mM l-glutamate (○), l-aspartate (▵), l-glutamine (□), or l-asparagine (▿) or no added amino acid (⋄); a parallel control culture containing Na⁺ and Ca²⁺ (4.0 mM) is included (•). The initial pH of all cultures was 6.0.