FIG. 6.
Use of lacZ to report expression of deleted genes. (A) An exponentially growing culture of TP8503 yacK ↔ FLK2 was divided in two (arrow), and one half was induced by addition of 0.5 mM CuSO4. Samples of both cultures were collected for enzyme analysis. β-Galactosidase activity in the induced culture quickly reached levels about six times greater than that in the uninduced control. Solid bars, culture induced with 0.5 mM CuSO4 (Cu); open bars, control culture. “X” indicates the OD600, which was the same for both cultures. M.U., Miller units. (B) ruvA expression after SOS induction with mitomycin C. At an OD600 of 0.1, cultures were divided and inducer was added to one of the cultures. At 100 min, samples were taken for assay. Lane 1, ruv+ control; lane 2, ruvA reporter replacement; lane 3, same as lane 2 but with the reporting cassette in the opposite orientation. Open bars, β-galactosidase activity control; solid bars, induced cultures.