FIG. 5.

Effect of envZ and acetyl phosphate on acid induction of ompC-lacZ in exponential-phase cells. The cells were grown to approximately 10⁸ per ml at 37°C in EG medium (pH 7.7 or 5.8 as indicated). β-Galactosidase activity was assayed according to the method of Miller (41). The values are representative of triplicate experiments. +, present; −, absent.