Phenotypic analyses of S. aureus cells and culture supernatants derived from flow biofilms and planktonic cultures grown for 12 h.
A, pH values of a medium control, planktonic, biofilm ECM, and biofilm FT samples are indicated as the mean ± S.D. of quadruplicate experiments. B, Hemolysis assay of a growth medium control, 0.2% SDS as a positive control, cell-free biofilm ECM and FT samples, respectively. Data are displayed as mean values ± S.D. of triplicate experiments. C, G. mellonella larvae were injected with 5 μl of cell-free biofilm ECM or FT samples, respectively. Noninjected larvae and growth medium supplemented with BSA served as controls. The survival of 15 larvae per experiment was monitored for 68 h. D, Freshly cultivated biofilm and planktonic cells were used to inoculate fresh growth medium supplemented with 3 m and 4 m NaCl, respectively. CFU were determined after 0, 24, 48, and 72 h. Data are displayed as mean values ± S.D. of triplicate experiments relative to the CFU (100%) of time point 0 h. * = p < 0.05, ** = p < 0.01, *** = p < 0.001, **** = p < 0.0001. ECM = Extracellular matrix, FT = Flow-through.