Figure 5.

pH effect on kinetics of O₂ and N₂O depletion. O₂ and N₂O consumption, and NO and N₂production by E. meliloti 1021 when incubated in the presence of 10 mM NO⁻₃ in minimal medium at pH 6 (A), pH 7 (B) and 8 (C), and an initial O₂ concentration of 02% in the headspace plus 5% N₂O. Cultures with an initial OD₆₀₀of 0.01 were vigorously stirred at 700 rpm. Plotted values are average of three replicate flasks for each treatment, with standard deviation (SD) as vertical bars (n = 3). The decline in N₂O concentration at pH = 6 is due to sampling loss, not biological reduction of N₂O to N₂.