Table 3.

Point mutations and amino acid changes in emrR and gyrA genes associated with increased resistance to nalidixic acid in C. violaceum.

Gene	Amino acid position	Nucleotide change	Amino acid change	No. of mutants	MICa Nalidixic acid (μg/mL)
gyrA
	84	GAT→GGT	Asp→Gly	4	16
		GAT→AAT	Asp→Asn	2	16
	85	ACC→ATC	Thr→Ile	15	512
	89	GAC→GGC	Asp→Gly	4	16
emrR
	92	CGC→CAC	Arg→His	2	4
	145/146	TTCGAA→TA	Phe/Glu del	1	4

^aMIC values determined by streaking strains on LB plates with increasing concentrations of nalidixic acid (MIC 1 μg/mL for WT under this condition).