FIG. 3.

Metabolism of nitrite and NO by N. meningitidis. NO concentration was measured with an iso-NO electrode (World Precision Instruments). Suspensions containing 3 ml of N. meningitidis at a concentration of 0.1 mg of protein ml⁻¹ in MHB were sparged with nitrogen gas until anaerobic in a 7-ml water-jacketed chamber kept at 30°C. The cell suspension was stirred with a magnetic flea, and the chamber was kept anaerobic with a rubber septum through which the NO electrode probe was inserted. Traces show the effects of 1 mM nitrite on wild-type (A) and norB (B) strains and the effect of 8 μM NO on cycP (C) and norB (D) strains.