TABLE 5.

LexA-dependent control of a Fels-2 tum::lac fusion^a

Strain	Relevant genotype	β-Galactosidase activity in F′128-Fels-2 tum::lac strains
		LB	LB + mitomycin C (1 μg/ml)
TT23764	recA+lexA+	3.6	95.2
TT23765	lexA41::Cam	168.2	180.3

^aBoth strains contained the proB1567::Tn10 and sulA46::Spc insertions and lacked prophages Fels-2, Gifsy-1, and Gifsy-2. They also contained the plasmid F′128 (P_tum::lacZ⁺), which encodes a lacZ gene regulated by the control region of the Fels-2 tum gene. Assays were done with at least two cultures, each tested in duplicate. Units are nanomoles of nitrophenol produced per minute per optical density unit at 650 nm of cell suspension.