Figure 5. Cell elongation phenotypes of P. aeruginosa mutant strains under aerobic and anaerobic growth conditions.

(A) Anaerobic respiratory (denitrification) pathway. Enzymes involved in each reduction step are termed nitrate reductase (NAR), nitrite reductase (NIR), nitric oxide reductase (NOR), and nitrous oxide reductase (NOS), respectively. (B–J) DIC images of PAO1 (B, C, and D), ΔnarG (E, F, and G), ΔnirS (H, I, and J). Bacterial strains were grown for 18 hours in LB +15 mM NO₃ ⁻ aerobically (B, E, and H), anaerobically (C, F, and I), and anaerobically in LB (pH 7.8) +15 mM NO₂ ⁻ (D, G, and J). A scale bar of 5 µm is indicated in the bottom left of each panel. * No discernible growth was observed in these two cultures and thus, cells were concentrated for image acquisition.