TABLE 1.

Comparison of N. europaea growth characteristics and NH₄⁺ to NO₂⁻ conversion stoichiometry during NH₃- and O₂-limited steady-state growth

Growth condition	Period (days)	OD600a	Input NH3b (mmol day−1)	NH3 consumeda (mmol day−1)	Steady-statea NH4+ (mmol liter−1)	Steady-statea NO2− (mmol liter−1)	N balancea,c,d (mmol)	Ammonia oxidation ratea,d (qNH3) (mmol g [dry cell weight]−1 h−1)	Apparent growth yielda,d (Y) (g [dry cell weight] mol−1 NH3)
NH3 limited	7–16	0.15 ± 0.01	14.4	14.2 ± 0.1	0.9 ± 0.5	60.1 ± 1.4	61.0 ± 1.7 A	24.04 ± 0.93 C	0.42 ± 0.02 C
	9–11	0.15 ± 0.004	14.4	14.2 ± 0.1	0.9 ± 0.4	59.1 ± 1.4	60.0 ± 1.8 c	24.73 ± 0.53 c	0.40 ± 0.01 c
O2 limited growth	23–32	0.07 ± 0.01	14.4	7.5 ± 0.4	28.9 ± 1.5	24.1 ± 0.8	52.8 ± 1.8 B	26.44 ± 2.28 D	0.38 ± 0.03 D
	28–30	0.07 ± 0.0005	14.4	7.5 ± 0.3	28.6 ± 1.1	24.3 ± 1.4	52.9 ± 2.4 d	28.51 ± 1.13 d	0.35 ± 0.01 d

^a Average values from 3 sampling days or 10-day steady-state period, ± standard deviations (see Table S1 in the supplemental material).

^b The NH₄⁺ concentration of the influx medium (60 mmol liter⁻¹) multiplied by the influx rate (0.24 liter day⁻¹).

^c Sum of effluent NH₄⁺ and NO₂⁻ concentrations.

^d Letters A and B represent highly significant differences (P ≤ 0.01), and letters C and D represent significant differences (P ≤ 0.05) within parameters. Capital letters represent comparisons between 10-day periods, whereas lowercase letters represent comparisons between 3-day periods.