FIGURE 2.

The instantaneous coupling of CH₄ oxidation to NO₂^- reduction in Methylomicrobium album strain BG8 under hypoxia. Experiments were performed in a closed 10 mL micro-respiratory chamber outfitted with an O₂ and N₂O microsensor and logged with Sensor Trace Basic software. O₂ (black diamonds) and N₂O (gray circles) were measured using microsensors. Cells of M. album strain BG8 were harvested as described in the materials and methods and resuspended in nitrogen free mineral salts medium. Arrows mark the addition of CH₄ (∼300 μM) and NaNO₂ (1 mM) to the micro-respiratory chamber in all panels. There is no measureable denitrification activity in the absence of NO₂^- (A); denitrification activity is dependent on CH₄ and NO₂^- (B).