FIG 4 .

NDH-2 is important for respiration and for maintenance of NADH/NAD ⁺ redox balance. Cells were grown under respiration permissive (white bars) or nonpermissive (black bars) conditions and harvested in early stationary phase. (A) Oxygen consumption assays were normalized to an OD₆₀₀ of 0.3 and started by the addition of 0.2% glucose. (B) The NADH/NAD⁺ ratio was determined for the WT and isogenic mutant strains. Data are plotted as the average ± SD from three independent experiments. (A) **, P < 0.005 via two-way analysis of variance (ANOVA) with Tukey’s posttest for the indicated comparisons. No significant difference was observed between nonpermissive and permissive conditions for the Δndh or Δndh Δnox2 mutants. (B) n.s., not significant, *, P < 0.05, **, P < 0.005, and ***, P < 0.001, via two-way ANOVA with Dunnett’s posttest compared to wild-type under nonpermissive conditions.