Figure 7.

Adherent GAG-treated P. aeruginosa biofilms exhibit increased resistance to colistin. Biofilms of wild-type P. aeruginosa PA14 were growth in the presence of de-N-acetylated GAG-containing culture supernatants from wild-type A. fumigatus culture supernatants (WT CS) and then treated with 0.00117 mg/mL of colistin. Viability of P. aeruginosa was determined by XTT tetrazolium salt metabolism. Bars represent the means ± standard deviations of XTT supernatant measured at 450 nm of 5 independent experiments. A significant decrease in absorbance is indicated by * (p < 0.0005) between untreated and treated groups and between treated groups and as determined by paired t test.