Fig. 4.

Semiquantitative analysis of biofilm density. The biofilms of S. epidermidis RP62A were detected by semiquantitative microtiter plate assay. Briefly, overnight cultures of bacteria were diluted 1:200 and cultured in a 96-well plate (200 μl/well) at 37°C for 12 h, and then the biofilms were treated with the six different conditions denoted in the figure. The biofilm was washed gently 3 times with PBS and stained with crystal violet, and the absorbance at 570 nm was measured by a spectrophotometer. Data are presented as means plus standard deviations (n = 12). The error bars represent 95% confidence intervals. Asterisks denote statistically significant differences: *, P < 0.05, and **, P < 0.01. # denotes no significant difference between groups, P > 0.05.