FIG 3.

Effect of silencing nifJ, iscR, or xdh on resistance in the ΔfeoB1 mutant and WT strain. (A) In the WT strain, depletion of mRNA for feoB1, nifJ, iscR, and xdh occurs when antisense sequences (AS) are induced with xylose (2%, wt/vol) (A), but when the WT was grown in various concentrations of metronidazole, resistance was seen only with depletion of feoB1 (i.e., growth at 0.5 μg/ml and MIC of 1 μg/ml). The MIC for strains expressing other antisense sequences was 0.25 μg/ml. (C) Conversely, in the ΔfeoB1 mutant, expression of any of the three antisense sequences caused resistance (i.e., MICs of 8 μg/ml versus 1 μg/ml against the ΔfeoB1 mutant).