FIG 6.

Prestarvation reduces activity of the constitutive Ptet promoter. (A and B) Plasmid pRG278 carrying Ptet-yfp was placed in phoBR deletion strain BW25142 for analyses of total fluorescence (A.U., arbitrary units) (A) and promoter activity (B) during Pi starvation as described in Materials and Methods. Gray-shaded areas indicate growth under the Pi-replete condition. (C and D) ODs of bacterial cultures and the OD-normalized first derivatives, indicating the real-time growth rates, are illustrated in panels C and D, respectively. Data from cells without prestarvation of Pi are shown with black lines, while red lines indicate data from prestarved cells. The average of results from 8 individual wells from one microplate assay is shown for each condition, and error bars indicate SD. Similar patterns of reporter activity were observed for independent assays.