FIG. 2.

Effects of the spo0A225 mutation on transcription from two Spo0A-dependent promoters. (A) spoIIE-gus expression; (B) spoIIA-lacZ expression. Strains were cultured and assayed as described in Materials and Methods. T₀ marks the end of exponential growth. Samples were collected at 1/2-h time points from T₋₂ until T₄ and then hourly until T₈ unless otherwise indicated. Open squares, wild type (JKH73); filled circles, spo0A225 strain. Data from at least three independent trials were averaged. Error bars, standard error of the mean (SEM). One unit of activity is defined as one picomole of MUG hydrolyzed per milliliter of culture sample per minute, normalized for culture cell density (turbidity).