FIG 1.

A simplified schematic of electron transport and NO/N₂O-producing pathways in N. europaea. Solid lines indicate confirmed and dashed lines indicate postulated reactions or electron transfer processes. Abiotic N₂O production is indicated in blue. NADH dh, NADH dehydrogenase (complex I); AMO, ammonia monooxygenase; HAO, hydroxylamine dehydrogenase; NirK, nitrite reductase; bc₁, cytrochrome bc-I complex (complex III); HCO A1, heme-copper-containing cytochrome c oxidase A1-type (complex IV); sNOR/HCO B, heme-copper-containing NO reductase/heme-copper-containing cytochrome c oxidase B-type (complex IV); cNOR, heme-iron-containing nitric oxide reductase.