Table 1.
Effects of arginine and ArgR on gltB::lacZ expression
| Effect tested | Strain/condition | LacZ activity (units)1 | Normalized data |
| LP1000 (rph) | 11722 | (1.00) | |
| Addition of arginine3 | LP1000 + Arg | 660 | 0.56 |
| LP1270 | 900 | 0.77 | |
| LP1270 + Arg | 953 | 0.81 | |
| LP2020 (rph+) | 736 | 0.63 | |
| LP2020 + Arg | 402 | 0.34 | |
| Deletion of ArgR | LP1050 (ΔargR) | 2981 | 2.54 |
| LP1050 + Arg | 3035 | 2.59 | |
| LP2020 (rph+)4 | 648 | 0.55 | |
| LP2023 (rph+ ΔargR) | 1283 | 1.09 | |
1 One unit of LacZ (β-galactosidase) activity is defined as 1 nmol of ONPG hydrolyzed per min.
2 Samples were taken at several culture densities, and the resulting LacZ activity was plotted vs. culture density (as in Fig. 6). The activity was calculated from the slope of the line; in every case, the correlation coefficient of the least squares regression was ≥ 0.99.
3 Arginine hydrochloride was added to the medium to a final concentration of 7.5 mM.
4 These results were obtained on a different day from the other experiments.