Table 2.
Calibration of the selection system
| Harbored enzyme variant | Tetracycline concentration, μg/ml |
||||
|---|---|---|---|---|---|
| 0 | 0.5 | 1 | 2.5 | 5 | |
| MjPDT | 2 | 2 | 2 | 3 | 3 |
| WT EcPDT | 2 | 2 | 2 | 3 | 5 |
| W226A EcPDT | 2 | 3 | 4 | 7 | >12 |
| N160A EcPDT | 8 | 12 | >12 | >12 | N.G. |
Number of days needed for single-colony formation (colony diameter: 0.5–1 mm) at 30°C. KA34/pMHEtetCDH transformants producing one of the four PDTs were picked from phenylalanine-supplemented plates and streaked out onto selective M9s plates as described in Materials and Methods. N.G., no growth observable.