TABLE 1.

Effect of colicins on the viability of E. coli F4 (K88) and F18 after 3 h of incubation^a

E. coli strain	ColE1		ColN
	Dose (μg/ml)	CFU/ml	Dose (μg/ml)	CFU/ml
F4 (K88)	0	3 × 109	0	3 × 109
	50	5 × 106	10	1.1 × 107
	200	4 × 106	50	6 × 105
F18	0	2 × 109	0	2 × 109
	1	1.2 × 106	50	1 × 106
	100	5 × 104	100	4 × 105

^aInitial CFU/milliliter were 6 × 10⁷ and 1 × 10⁷ for E. coli F4 (K88) and F18, respectively.