Figure 9.

dacA is dispensable for the growth of S. aureus under anaerobic conditions. A, schematic overview of aerobic (left panel) versus anaerobic (right panel) respiration in S. aureus. Under aerobic conditions, oxygen is used as the terminal electron acceptor through the Qox system. In the absence of oxygen but in the presence of nitrate (NO₃⁻), anaerobic respiration with nitrate as terminal electron acceptor through the nitrate reductase can occur. B, agar plate images. 10⁻⁴ dilutions of WT and dacA mutant cultures were plated on TSA plates, the plates incubated under aerobic or anaerobic conditions, and images taken after overnight incubation at 37 °C. Insets show representative magnified areas of the respective plate. C and D, plating efficiencies of WT and dacA mutant strains. Bacterial suspensions were plated on TSA (C) or TSA plates containing 20 mm KNO₃ (D), and the plates were incubated aerobically or anaerobically as stated. Average CFUs per ml of culture per A₆₀₀ unit and standard deviations from three experiments were plotted.