Figure 5.

Plasmid-borne parS reduces the fitness of Caulobacter. Low-copy number plasmid harbouring individual parS site was conjugated from E. coli S17–1 to wild-type Caulobacter. The same number of E. coli and Caulobacter cells were used for each conjugation. A ten-fold serial dilution was performed and spotted on PYE plates supplemented with both nalidixic acid and kanamycin or just with nalidixic acid. Addition of kanamycin enforces the retention of parS plasmid, while omitting kanamycin allows plasmid loss. All cells were spotted on the same +kanamycin or –kanamycin plates, and pictures were taken after 3-day incubation at 30°C.