Figure 3
Plasmid segregational stability. Salmonella SL7207 with the stabilized pZS1205 plasmid (□) or the nonstabilized pZS1204 plasmid (■), each expressing (OVA-CD4)-MisL, with the stabilized pZS1205-4 (∆) that expresses four copies of OVA-CD4 fused to MisL, or pUC18-OVA (▲) that expresses full-length ovalbumin were grown in LB broth at 37°C without antibiotics. Serial passages were conducted daily by diluting the overnight cultures into fresh media (10−3 dilutions for the first week and 10−5 dilutions for later). Plasmid stability was estimated by calculating the numbers of ampicillin-resistant CFUs divided by the total number of CFUs and multiplying the number by 100 to obtain a percentage of bacteria containing the plasmid.