FIG. 4.

Northern hybridization analysis of the c2 ori fragments that support plasmid replication. Twenty micrograms of total RNA from L. lactis cells harboring a plasmid was electrophoresed on an acrylamide gel, blot transferred, and then probed with a PCR product (template pLP206; primers ori1 and ori7) and detected by the ECL system. MG1363, no plasmid; pLP constructs, MG1363 transformed with the plasmids indicated; NZ9000 and NZ9800, two lactococcal host strains for pLP212, in which the ori transcript is placed under control of the nisA promoter; + nisin, growth in the presence of nisaplin; − nisin, growth in the absence of nisaplin.