Fig. 1

E. faecalis strains 16C51 (a) and 16C106 (b) were treated with sub-MIC concentrations of isobavachalcone for 24 h or left untreated. The growth of planktonic cells was detected by OD600. Panels (c) and (d) show the effect of sub-MIC isobavachalcone on biofilm formation of the two isolates. Data in (a, b) are means ± SD of three replicates; spots mark the mean. Biofilm formation was determined by crystal violet staining and absorbance measurement at 570 nm for 24 h (Table S2). Data in (c, d) are means ± SEM of three independent experiments. Each treatment was compared with the control; significant differences (*P < 0.05, **P < 0.01; Student’s t-test) were marked, n = 3