FIG 6.

Overexpression of phoB increases the level of fimZ expression. The strains were shaken overnight in LB growing at 37°C. The wild-type bacterium is S. enterica serovar Typhimurium strain SL1344. RL291 is an SL1344 derivative that contains a pstS mutation that causes the overexpression of phoB. The BJ3184 strain is the RL291 strain containing a defined fimZ::cam mutation. Each strain tested contained the fimZ::lacZY reporter plasmid pISF239. The strains were grown in LB overnight with shaking, and expression levels were determined by measuring lacZ output as measured by β-galactosidase activity. The experiment is representative of an assay which was repeated in triplicate on three separate days.