Extended Data Figure 6. Batch incubations with nitrite, urea and without substrate.
a and b, Nitrite (triangles) oxidation by the enrichment culture to nitrate (squares) (a) in the absence and (b) in the presence of ATU. The ammonia (diamonds) in (b) presumably stems from biomass decay and is not oxidized due to ATU inhibition. c, Urea conversion to ammonium (diamonds) and subsequent oxidation to nitrate (squares). d, No-substrate control; minor amounts of ammonium (diamonds) presumably stem from mineralisation of degrading biomass, leading subsequently to nitrate (squares) formation. Symbols in all plots represent averages of three independent incubations; ammonium was determined in single measurements, nitrite and nitrate in duplicate (a and b) or triplicate (c and d). Error bars represent standard deviations of three biological replicates.