Table 1. Exact Integration Statistics.
| Without Counterselection | With Counterselection | |||||||
|---|---|---|---|---|---|---|---|---|
| tetA (Blue/White) | % Correct | galK (Blue/White) | % Correct | tetA (Blue/White) | % Correct | galK (Blue/White) | % Correct | |
| atpI | 888 / 25 | 97.3 | 54 / 829 | 6.1 | 1148 / 15 | 98.7 | 720 / 6 | 99.2 |
| nth | 1104 / 64 | 94.5 | 49 / 248 | 16.5 | 1375 / 35 | 97.5 | 601 / 9 | 98.5 |
| ygcE | 194 / 559 | 25.8 | 51 / 353 | 12.6 | 1052 / 306 | 77.5 | 232 / 200 | 53.7 |
Colony counts resulting from exact integration of the lac operon at each of three loci (atpI, nth, and ygcE) using either the tetA or galK landing pad. Counts are given both before and after counterselection against landing pad retention using 5% w/v sucrose and either 6 mM NiCl2 (for tetA landing pad) or 0.2% w/v DOG (for galK landing pad). The percent correct integrants was calculated as the percentage of blue colonies after growth on 2 mM IPTG and 20 μg/ml X-gal.