FIG. 2.

[¹⁴C]-Phenyl-thio-β-d-glucuronide (PTG) transport in different host-vector systems. Each line represents curve fits of mean values of triplicate analyses at each of the time points; error bars are standard deviations. PTG was used at 50 μM. (A) Induction of the complete gus_CE1 operon on plasmid pKW219 or the gus_K-12 operon on plasmid pKW220. The host E. coli strain KW1 has the entire gus operon deleted. Cells were induced with 1 mM p-nitrophenyl-β-d-glucuronide for 40 min during logarithmic growth. Solid upward triangles, PTG uptake into cells with induced gusABC_CE1 operon (line represents curve fits); open downward triangles, cells with uninduced gusABC_CE1 operon; solid squares, cells with induced gus_K-12 operon; solid circles, vector control [KW1(pLARF3)]; solid downward triangle, strain control (KW1). (B) Expression of the gusB_CE1 and gusC_CE1 genes under control of the λ O_LP_L promoter in the λ lysogen strain AR120. Strains were induced with 40 μg of nalidixic acid per ml for 3 h at mid-log phase. Solid squares, cells with induced gusBC_CE1 genes on plasmid pWJL4; solid downward triangles, cells with uninduced gusBC_CE1 genes on plasmid pWJL4; open squares, cells with induced gusB_CE1 gene alone on plasmid pWJL6; open diamonds, cells with induced gusC_CE1 gene alone on plasmid pWJL11; solid upward triangles, vector control [AR120(pAD284)]. (C) Expression of the gusB_CE1 and gusC_CE1 genes under control of the tac promoter. Strains of E. coli NO2947 containing the plasmids below were induced with 1 mM IPTG for 14 h after inoculation in minimal medium. Solid upward triangles, cells with induced gusBC_CE1 genes on plasmid pWJL24; solid downward triangles, cells with uninduced gusBC_CE1 genes on plasmid pWJL24; open upward triangles, cells with induced gusB_CE1 gene alone on plasmid pWJL26; open diamonds, cells with induced gusC_CE1 gene alone on plasmid pWJL31; solid circles, vector control [NO2947(pTTQ18)].