TABLE 4.

2,2"-Dipyridyl affects the transcription of inaA and rob promoters differently depending on the growth phase of the cells^a

Strain (promoter-lacZ fusion)	2,2"-Dipyridyl concn (mM) or ratiob	β-Galactosidase activity (Miller units) at various growth phases
		Early log	Mid log	Stationary
M542 (rob)	0	240	469	732
	5	396	507	741
	Ratio	1.7	1.1	1.0
M871 (inaA)	0	16	16	20
	5	89	131	119
	Ratio	5.6	8.2	6.0

^aCells were grown from small inoculae in LB broth to an A₆₀₀ of 0.07 (early log phase) or 0.5 (mid-log phase) or overnight to an A₆₀₀ of 2.5 (stationary phase). The samples were then diluted with an equal volume of prewarmed 10 mM 2,2"-dipyridyl in LB broth. After aeration for 1 h at 37°C, the β-galactosidase activity was assayed.

^bThat is, the ratio of activities in the cells treated with dipyridyl to that in the untreated cells.