FIG 4.
Cell-free Psl promotes S. aureus killing under in vivo-like conditions. (A) Twenty-four-hour S. aureus USA300 biofilms were incubated with or without P. aeruginosa PAO1, ΔPpsl, or pagP::Tn spent medium for 5 h. Biofilm biomass was quantified by crystal violet staining. Data are means and SD; individual points indicate biological replicates (N = 5; n = 3). Significance was determined using one-way ANOVA. *, P < 0.05, and ns, not significant, compared to the medium-only control. (B) S. aureus survival when cocultured with P. aeruginosa PAO1, ΔPpsl, or pagP::Tn in SCFM2 for 7 h. Data are means and SD; individual points indicate biological replicates (N = 3; n = 3). Significance was determined using Student’s t test. *, P < 0.05 compared to PAO1.