FIG 3.
(A and D) Transcription of nrfA (□) and nirB (■) in Citrobacter sp. DNRA3 (A) and nirB (◇) in Enterobacter sp. DNRA5 (D) cells as 1 mM NO3− (●) was reduced to NH4+ (▲) via NO2− (○). (B, C, E, and F) Changes to the amounts of NO2− were monitored in the chloramphenicol-treated resting cultures of Citrobacter sp. DNRA3 (B and C) and Enterobacter sp. DNRA5 (E and F) harvested before (B and E) and after (C and F) NO3− depletion and resuspended in fresh medium containing 2 mM NO2− (○) or 2 mM NO3− (●). All experiments were performed in biological replicates (n = 3), and error bars represent the standard deviations.