Fig 1.

Oxidation of Fe²⁺ (gray bars, left y axis) with reduction of ¹⁵NO₃⁻ (closed circles, right y axis) and production of ³⁰N₂ gas (empty circles, right y axis). “Ca. Brocadia sinica” cells (2.5-ml sample in a 5-ml glass vial) were incubated at 37°C with ¹⁵NO₃⁻ (2.5 mM) and Fe²⁺ (15 mM). Error bars indicate the range of SDs derived from three replicated vials.