TABLE 5.

Effect of growth medium on mutation^a

	Median mutation frequency (106)
Strain	Lac−→Lac+		Rifs→Rifr
	Minimal	LB	Minimal	LB
BS40/F′CC107	0.38	0.38	0.067	0.024
BS40mutS/F′CC107	240	380	0.67	1.1
BS40dnaE1336/F′CC107	0.63	1.0	0.23	0.42
BS40dnaE1337/F′CC107	0.83	0.97	0.047	0.094
BS40dnaE1338/F′CC107	1.6	39	0.05	4.8
BS40dnaE1338mutS/F′CC107	1,100	850	13	47
BS40dnaE1338mutS/F′CSH143	28	18	43	58
BS40dnaE173/F′CC107	15	1,300	0.92	26
BS40dnaE173mutS/F′CC107	6,500	470	56	70
BS40dnaE173mutS/F′CSH143	2.5	1.8	19	33

^aRecorded median of three values for each entry except BS40dnaE1338mutS/F′CC107 and BS40dnaE173mutS/F′CC107, for which the value is the median of seven replicates.