FIG. 1.

Involvement of pocR and the pdu operon in hilA repression by 150 mM 1,2-propanediol. hilA expression levels reported by pSN849 in strains SL1344 (WT), SN2036 (ΔpocR::aphT), SN2040 (ΔpduCDEGH::aphT), and SN2036 harboring pPocR (ΔpocR::aphT/pPocR) were monitored through β-galactosidase assay after cultivation in media supplemented with the indicated concentrations of a mixture of R-(−)- and S-(+)-1,2-propanediol. Throughout the experiments in this study, LB supplemented with 0.1 M NaCl and 0.1 M sodium phosphate buffer (pH 7.0) was employed as the basic medium. 1,2-Propanediol or sodium propionate was added at the indicated final concentrations when used. Bacterial cultures in the indicated media were incubated and kept static at 37°C until the optical density at 600 nm reached approximately 0.7. The cultured bacteria were harvested, suspended in Z buffer (30), and used for the β-galactosidase assay. Error bars indicate standard deviations.