FIG 4.

Effect of cbb₃ oxidases on DNA synthesis. (A) Relative cellular dNTP levels at 14 h as determined by a DPA assay. Anoxic incubation of P. aeruginosa was performed using Erlenmeyer flasks containing argon gas and LBN medium at 37°C with shaking at 200 rpm. Cell extracts containing equal amounts of protein were used in this assay. The values represent the means ± standard deviations from three independent experiments. (B) Relative CFU at 24 h in LBN medium supplemented with 100 nM vitamin B₁₂. The values represent the means ± standard deviations from three independent experiments. NS, not significant. *, P < 0.05 (unpaired two-tailed Student's t test). (C) DIC images at 24 h. Three independent experiments were carried out, and representative images are shown.