FIG. 6.
Effect of gad mutations on the protective role of glutamate. Strains ENZ1588 (gadC) (⋄ and ⧫) and ENZ1592 (gadA gadBC) (▵ and ▴) were inoculated 1:500 (time zero) into Pi-limiting medium (0.1 mM Pi plus 40 mM glucose) without glutamate (GLU) (open symbols) or with 30 mM glutamate (solid symbols) and incubated further under aerobic conditions. Parentheses indicate that no CFU were detected when 20-μl portions of the cultures were directly plated. The values are the means ± standard deviations for two independent cultures or for one culture (⋄) representative of several determinations. The data for the wt strain with no glutamate (○) and with 30 mM glutamate (•) are from Fig. 5. The final pHs of the cultures on day 21 of incubation with glutamate are indicated on the right.