FIG. 7.

Ectopic expression of ropB does not alter the expression kinetics of speB. The chimeric plasmid pMNN23 contains ropB under the control of a promoter expressed during the early logarithmic phase of growth. Levels of protease activity produced in various strains at the indicated time points were measured with the substrate fluorescein isothiocyanate-casein and are reported relative to the activity of the wild-type strain at 20 h. The strains analyzed included HSC5 (wild type), MNN100 (ΔropB), MNN100 plus ectopically expressed ropB (ΔropB + pMNN23), and HSC5 plus ectopically expressed ropB (wild type + pMNN23). The data presented represent the mean and standard error of the mean derived from seven independent experiments.