Figure 4.

Cells from the CH₄/${\text{NO}}_3^{-}$ continuous culture (0.6 L; D = 0.026 h⁻¹; OD₆₀₀ = 1.3; O₂ limited) perform denitrification when nitrite was added to the reactor vessel. The concentrations of ${\text{NO}}_2^{-}$ (open rectangles), NO (solid line) and N₂O (open circles) were measured before and after addition of 50 μM ${\text{NO}}_2^{-}$ (arrow). Duplicates of individual values do not deviate more than 5 and 10% for ${\text{NO}}_2^{-}$ and N₂O, respectively.