FIG. 4.
Production of HA/protease as an indicator of ectopic expression of RpoS in ΔrpoS and ΔrpoS Δhns mutants. Strains AJB50ΔlacZ (ΔrpoS) and AJB81 (Δhns::Km ΔrpoS) containing plasmid pTTRpoS were grown in TSB medium to an OD600 of 1.0 and divided in half. One half was induced by the addition of IPTG, and the other half (uninduced) was used as a control. Samples were taken at different times to determine the production of HA/protease by using the azocasein assay described in Materials and Methods. Each data point is the mean for three independent cultures. Error bars, standard deviations.