FIG 3 .

NO₃ consumption and NO production in mutants that overexpress RND pumps. The NO₃ (A) and NO (B) concentrations were measured using a nitric oxide colorimetric assay kit (Abcam, Inc., Cambridge, United Kingdom). After 24 h of culture, all strains had consumed the nitrate present in the LB medium (A). JFL10 consumes the largest amount of nitrate. These results correlate with the levels of nitric oxide production (B) as JFL10 also produces the largest amount of nitric oxide. These results indicate that the nitrate respiratory chain is active in all the mutants analyzed in this study. The figure shows the means and standard deviations from three different experiments. In all cases, the differences between the wild type and the overexpressing strains were statistically significant (P < 0.05).