FIG. 4.

Differential rates of Φ(napF-lacZ) expression. Cultures of the λΦ(napF-lacZ) strains VJS4734 (narL⁺) and VJS4799 (narL::Tn10) were grown anaerobically in MOPS-glucose medium supplemented with 5 mM nitrate. (A) Growth curve (•) and nitrite concentrations (⧫) for strain VJS4734. This pattern was typical for strains used in this experiment and in the experiments whose results are shown in Fig. 5 and 6. (B) Total β-galactosidase activities in cultures of strains VJS4734 (▪) and VJS4799 (□) and, for reference, nitrite concentrations in the culture of strain VJS4734 (⧫). OD₆₀₀, optical density at 600 nm.