FIG. 2.

Dynamic expression of the flagellar, SPI1, and type 1 fimbrial genes. Time course dynamics of the P_flgA (flagellar), P_hilA (SPI1), and P_fimA (type 1 fimbrial) promoter activities in wild-type cells as determined using luciferase transcriptional reporters. For reference purposes, the optical density (OD600) was plotted to illustrate how each system is activated during different phases of growth. In these experiments, cells were first grown overnight at 37°C in LB without salt and then subcultured 1:500 in fresh LB-1% salt. Cells were then grown statically with luminescence, and optical density readings were taken every 20 min. Average promoter activities from three independent experiments on separate days are reported. For each experiment, six samples were tested. Error bars denote standard deviations. A.U., arbitrary units.