Table 3.

The MICs of several antimicrobials and gene expressions of acrB and multiple regulator genes in laboratory-selected mutants.

Strain no.	Selecting agenta	MIC (mg/L)					mRNA expressionc
		Enrofloxacin(2)b	Ampicillin (32)b	Oxytetracycline (16)b	Kanamycin (64)b	Spectinomycin(128)b	acrB	ramA	soxS	marA	rob
582		0.0625	1	2	2	32	1.4	1.6	1.5	1.1	1.0
582/E	Enrofloxacin	0.25	4	4	2	32	6.9	39.2	0.8	1.2	0.6
582/A	Ampicillin	0.25	4	8	2	32	7.7	89.5	0.3	1.2	0.8
582/O	Oxytetracycline	0.125	4	4	2	32	4.2	9.5	0.3	1.1	0.9
582/K	Kanamycin	0.125	2	4	4	32	3.1	9.0	0.5	1.3	0.6
582/S	Spectinomycin	0.0625	1	2	2	128	1.7	1.4	1.5	1.2	0.8
143		0.0625	1	2	2	32	1.3	1.2	1.2	1.1	1.0
143E	Enrofloxacin	0.25	4	4	2	32	4.3	45.2	0.6	0.9	0.7
143/A	Ampicillin	0.125	4	4	2	32	2.9	38.8	0.1	0.7	0.5
143/O	Oxytetracycline	0.0625	2	8	2	32	2.2	10.2	1.3	1.2	0.3
143/K	Kanamycin	0.0625	2	4	8	32	2.1	9.3	1.1	1.2	0.4
143/S	Spectinomycin	0.0625	1	2	2	128	1.6	0.9	0.9	0.7	0.7
1002		0.0625	1	2	2	32	1.2	1.0	0.8	1.0	1.0
1002/E	Enrofloxacin	0.25	4	4	2	32	8.0	29.8	0.1	1.2	1.0
1002/A	Ampicillin	0.125	4	2	2	32	2.4	16.1	0.1	0.3	0.5
1002/O	Oxytetracycline	0.125	2	8	2	32	2.2	14.7	0.2	1.2	0.9
1002/K	Kanamycin	0.125	2	4	4	32	2.4	14.2	0.3	1.0	0.9
1002/S	Spectinomycin	0.0625	1	2	2	128	1.1	1.4	0.4	1.1	0.9
916*		0.0625	1	2	2	32	1.1	1.1	0.8	0.9	0.9
916/E	Enrofloxacin	0.5	4	4	2	32	7.4	34.2	0.4	0.8	0.9
916/A	Ampicillin	0.25	4	4	2	32	8.5	58.2	0.1	0.9	0.8
916/O	Oxytetracycline	0.0625	1	4	2	32	2.2	3.5	0.2	1.0	0.9
916/K	Kanamycin	0.0625	1	4	8	32	2.2	6.5	0.1	1.0	0.6
916/S	Spectinomycin	0.0625	1	2	2	128	1.2	0.6	0.2	0.7	0.6
419*		0.0625	4	2	2	32	0.9	0.7	1.0	1.0	1.0
419/E	Enrofloxacin	0.25	16	4	2	32	5.7	24.2	0.2	1.7	0.8
419/A	Ampicillin	0.0625	8	2	2	32	1.6	32.5	0.3	0.7	0.9
419/O	Oxytetracycline	0.125	8	8	2	32	3.0	21.8	0.8	3.4	1.6
419/K	Kanamycin	0.0625	8	4	8	32	1.5	18.5	0.3	1.1	0.9
419/S	Spectinomycin	0.0625	4	2	2	128	0.9	1.1	0.4	2.1	1.2
03-197-1*		0.0625	>128	256	2	32	0.8	1.1	1.3	1.2	1.2
03-228-1*		0.0625	1	256	8	32	1.1	1.1	1.0	0.9	0.9
ZSC-14-1*		0.0625	1	256	2	32	1.1	1.0	1.0	1.0	0.8
ZSC-40*		0.0625	>128	256	2	32	0.9	0.8	0.8	1.1	0.9

MIC, minimum inhibitory concentration.

^aMutants were selected by exposing to fourth the MIC of the antimicrobials for each susceptible strain.

^bMIC data of antimicrobials except for spectinomycin in parental strains from a previous report (Asai et al., 2010). Parenthesis indicates break points.

^cRelative expression level of acrB and multiple regulator genes compared to average of six high accumulation susceptible strains represented as asterisks.