Extended Data Figure 7. Ammonia oxidation kinetics of N. viennensis.

Apparent half-saturation constants (K_m(app)) and maximum oxidation rates (V_max) for total ammonium were determined by fitting the data to the Michaelis-Menten kinetic equation. The red curve indicates the best fit of the data. Standard errors of the estimates based on non-linear regression are reported. See Methods for details of experiments and calculations. a, b, Total ammonium oxidation rates were calculated from microsensor measurements of NH₃ dependent O₂ consumption and discrete slopes over many substrate concentrations. Results for two biological replicates are shown here; a third biological replicate is shown in Fig. 1c. c, Total ammonium oxidation rates were calculated from microsensor measurements of NH₃ dependent O₂ consumption in a single trace measurement.