TABLE 3.
Expression of gadA and gadBC promoters in different genetic backgrounds
| Strain | β-Galactosidase activity (Miller units)a
|
|||||||
|---|---|---|---|---|---|---|---|---|
|
gadA
|
gadBC
|
|||||||
| pH 8.0
|
pH 5.5
|
pH 8.0
|
pH 5.5
|
|||||
| Exponential phase | Stationary phase | Exponential phase | Stationary phase | Exponential phase | Stationary phase | Exponential phase | Stationary phase | |
| Wild type | 1,488 ± 290 | 5,994 ± 1,151 | 2,009 ± 440 | 11,928 ± 2,611 | 1,375 ± 320 | 3,950 ± 796 | 2,395 ± 438 | 12,833 ± 2,829 |
| gadW | 1,044 ± 203 (70) | 2,245 ± 489 (37) | 1,776 ± 373 (88) | 12,493 ± 1,989 (104) | 944 ± 166 (67) | 2,130 ± 457 (54) | 2,897 ± 577 (120) | 9,245 ± 1,545 (72) |
| gadX | 177 ± 35 (12) | 672 ± 262 (11) | 313 ± 64 (16) | 3,177 ± 660 (27) | 177 ± 35 (13) | 621 ± 150 (16) | 301 ± 64 (13) | 4,055 ± 865 (32) |
| gadE | 102 ± 15 (7) | 252 ± 38 (4) | 165 ± 25 (8) | 416 ± 87 (3) | 130 ± 29 (9) | 420 ± 91 (10) | 215 ± 39 (9) | 670 ± 11 (5) |
a
The values are means ± standard deviations for 10 to 16 independent experiments. Cultures of E. coli MC4100 (wild type), MC4100gadW (gadW), MC4100gadX (gadX), and MC4100gadE (gadE) containing the chromosomal fusions gadA(−176/77)::lacZ and gadBC(−244/77)::lacZ were grown in LB-MOPS at pH 8.0 and LB-MES at pH 5.5 to the exponential and stationary phases. The values in parentheses are percentages of the corresponding activities for the MC4100 wild-type strain.