Fig. 5.

Optimal nitrite concentration and temperature for nitrite consumption by Nitrospira japonica J1. The inoculum was extracted from a pre-culture grown at 25°C. Optimal nitrite concentration was determined on the basis of the highest relative nitrite oxidation rate during three days’ incubation. Optimal temperature was determined on the basis of the highest nitrite consumption during three days’ incubation.

(A) Optimal nitrite concentration. Incubation temperature was 31°C. Nitrite oxidation rate at 20 mg-N L⁻¹ was the standard value.

(B) Optimal temperature. Initial nitrite concentration was 20 mg-N L⁻¹. All error bars indicate the standard deviation of triplicate measurements.