TABLE 4.

Effect of Cj1211 mutation and DNase I treatment on the emergence of spontaneous mutants that are resistant to FQ and streptomycin

Type of spontaneous mutant	Mean spontaneous mutation frequency ± SDa
	Wild type	JB201
FQr mutantsb	(3.0 ± 1.5) × 10−7	(9.8 ± 5.2) × 10−9
FQr mutants with DNase I treatmentc	(1.9 ± 1.1) × 10−7	NT
Strr mutantsd	(4.4 ± 3.0) × 10−6	(3.4 ± 2.2) × 10−8

^aMeans ± standard deviations of data for triplicate samples of a single experiment. NT, not tested; Str, streptomycin.

^bThe concentration of ciprofloxacin used is 1 μg ml⁻¹; the experiment was repeated five times.

^cDNase I was added to the bacterial suspension at a concentration of 100 μg ml⁻¹; the experiment was repeated six times.

^dThe concentration of streptomycin for plating was 3 μg ml⁻¹; the experiment was repeated five times.