TABLE 1.

Virion production by Ap^r gene-marked H-19B lysogens

Strain	Phage titer (PFU/104 CFU)a		Fold inductionc
	Before mitomycin treatment	After mitomycin treatmentb
MC4100 H-19B	4	25 × 104	6.3 × 104
MC4100 H-19B-Ap1	11	64 × 104	5.8 × 104
MC4100 H-19B-Ap2	7	18 × 104	2.6 × 104

^aSerial dilutions of chloroform-treated supernatants were plated on E. coli C600. 

^bCultures with an optical density at 600 nm of 0.5 were treated with mitomycin C at 250 ng/ml for 4 h. 

^cCalculated by dividing the number of PFU after mitomycin C treatment by the number of PFU prior to mitomycin C treatment.