Fig. 4.

Spermine but not spermidine can disperse a 24 h-preformed biofilm of P. aeruginosa H103. (A) 3D shadow (upper panel), side (middle panel), and top (lower panel) CLSM images representative of a 24 h-old biofilm of P. aeruginosa after bacterial labeling with SYTO 9 (green) before (H103) and after 2 h of treatment with spermidine (H103-Spermidine) or spermine (H103-Spermine) at 1 μM concentration. Images show representative data from three independent biofilm assays. (B) COMSTAT2 analyses were performed to determine maximum thickness, average thickness and biovolume of the control condition (P. aeruginosa H103 treated with ultrapure Milli-Q® water for 2 h), and the assays (P. aeruginosa H103 upon spermidine or spermine treatment for 2 h). The control parameters were put at 100 % (red line). The error bars represent the standard error of the means (SEMs) and are the result of the analysis of at least four views of each of the three independent biological assays. Statistics were performed by ordinary one-way ANOVA followed by Tukey's multiple-comparison test. Values that are significantly different are indicated by asterisks as follows: ∗∗, p < 0,01; ∗∗∗∗, p < 0.0001; ns, not significant.