FIG 3.

Effect of iron on the DFP inhibition of formation or further development of A. fumigatus biofilm. (A) A. fumigatus conidia were exposed to 625 μM DFP (D) alone, 625 μM DFP plus various concentrations of FeCl₃ (156 to 2,500 μM, shown as μM), or FeCl₃ alone for 16 h or not exposed (AF), before 24 h of further growth in fresh medium without added DFP or FeCl₃. (B) Preformed (16 h) A. fumigatus biofilms were exposed to 625 μM DFP alone, 625 μM DFP plus various concentrations of FeCl₃ (assays with 39 to 78 μM FeCl₃ not different than those with 156 μM; not shown), or FeCl₃ alone for 24 h or not exposed. Biofilms were quantified via XTT assay with absorbance at 490 nm. Twelve-well assays were used. Each condition was performed in triplicate, and the results were pooled from two to five separate experiments on different days. A single asterisk or dagger denotes a significant P value of <0.05, two asterisks or daggers denote a significant P value of <0.01, and three asterisks or daggers denote a significant P value of <0.001, compared to the experimental condition containing A. fumigatus alone (AF) (asterisks) or A. fumigatus plus DFP (daggers). The values shown are the means ± the standard deviations.