TABLE 3.

Toxicity of Lrp to E. coli K-12^a

Time (h)	No arabinose			Arabinose
	OD	Colonies (105) on LB	% on LB-CM	OD	Colonies (105) on LB	% on LB-CM
0	0.026	14	100	0.023	19	95
2	0.028	45	67	0.029	31	74
4	0.042	109	91	0.037	85	100
6	0.079	137	96	0.061	21	48
8	0.136	342	93	0.059	10	90
10	0.257	1,140	81	0.056	8	25
12	0.513	2,000	100	0.051	4	100
14	1.079	12,800	94	0.052	2	0

^aStrain MEW308 (MEW1 Δara/pBAD22lrp) was grown in glucose minimal medium, subcultured in glycerol minimal medium, and at the start of the experiment (h 0) subcultured with and without arabinose (100 μg/ml) (all in the presence of chloramphenicol [50 μg/ml]). Samples were taken at the times noted, their optical densities were determined at 600 nm, and then they were diluted and plated on LB. LB plates were incubated for 24 h at 37°C and then replicated on LB with chloramphenicol (LB-CM).