Fig. 1. Free ФH20 particles accumulate in cultures of lysogens in a QS-dependent manner.

(a) The concentration of plaque forming units (PFU ml⁻¹) in cell-free spent supernatants from cultures of V. anguillarum isolate 90-11-287 wildtype (WT), and QS mutant strains (ΔvanT and ΔvanO) is shown relative to the concentration of bacterial colony forming units (CFU ml⁻¹) in the cultures at the time of phage harvest. Solid bars represent the average of all the low-cell-density data points from Fig. 1C (LCD: OD₆₀₀ < 0.05) and hatched bars represent the average of all the high-cell-density data points from Fig. 1C (OD₆₀₀ > 1.0). An asterisk indicates a significant difference between LCD and HCD conditions (Welch’s t test, α = 0.05) and error bars represent the standard error of the mean (N = 6–8 for LCD and N = 10–11 for HCD) (b) Optical densities (OD₆₀₀) of cultures of wildtype (WT) and QS mutant strains (ΔvanT and ΔvanO) were measured at 1 h intervals during growth from low to high cell density. (c) The corresponding concentrations of phage particles in the cultures (PFU ml⁻¹) were measured by plaque assay. For (b) and (c), symbols represent the averages of triplicate independent experiments. Time = 0 h indicates the time of the first measurement.