Table 1.
Effect of pH on the growth of an amtB strain of E. coli at different ammonium concentrations
| Strain | [NH4+],* mM | pH 7
|
pH
5
|
|||||
|---|---|---|---|---|---|---|---|---|
| 5 | 1 | 0.5 | 0.2 | 5 | 1 | 0.5 | ||
| NCM1458 (11) | 59 | 61 | 65 | 69 | 67 | 78 | 79† | |
| (wild type) | ||||||||
| NCM2019 | 59 | 63 | 64 | 65 | 64 | 173 | 374† | |
| (amtB) | ||||||||
Data are doubling time (min). Cells were grown in N−C− medium, with glucose as carbon source and ammonium as sole nitrogen source. The glucose concentration was 0.4% at 5 mM ammonium and 0.2% at lower ammonium concentrations.
*
[NH4+ + NH3].
†
Doubling times of the corresponding strains carrying the Ptac-amtB plasmid were 85 min (NCM3014) and 83 min (NCM3015).