Fig. 6. Phage- and PICI-mediated plasmid transfer occurs in milk.

Donor strains (RN4220 SaPI1+ lysogenic or not for phage 80α) and recipient strain (RN4220 spontaneous rifampicin-resistant mutant) were incubated independently at 32 °C in milk containing ciprofloxacin. After 6 h, each donor strain was mixed with the recipient strain and plated on selective agar media. The figure shows the number of transductants per ml of donor strain detected. All data is the result of three independent experiments. No transductants were detected using the non-lysogenic donor strain. Plots indicate the median (bold bar) and range for each donor strain with individual data points shown as coloured circles. ***p = 0.0004, t-test (two-tailed). n = 3 experimental replicates.