FIG. 2.
Expression of norB monitored using a norB promoter lacZ fusion. β-Galactosidase activities were measured following aerobic growth or microaerobic growth. Aerobic samples were treated with 50 μM spermine NONOate when the OD600 was ≈0.3. The x axis indicates aerobic samples pretreatment and 1 h posttreatment with 50 μM spermine NONOate. Filled bars represent treated samples, and open bars represent control samples in which no NONOate was added. Likewise, microaerobically grown cultures were untreated (open bars), treated with spermine NONOate (black bars), or grown in the presence of 5 mM nitrite (striped bars). Panel A shows β-galactosidase activities in wild-type N. meningitidis, and panel B shows activities in the nsrR-deficient strain.