FIG 8.

Type 3 fimbriae mediate biofilm formation in response to lung surfactant. K. pneumoniae MGH 78578, KPPR1, and KPPR1 ΔmrkABC were cultured in MOPS minimal medium containing 20 mM lactate in the presence and absence of Survanta, phosphatidylcholine (PC), and cholesterol (Chol). After 18 h, the extracellular material remaining adhered to the culture dish was stained with 0.1% crystal violet. (A) Representative crystal violet-stained biofilms generated by each strain under the culturing conditions described above. (B) Biofilm-adhered crystal violet was solubilized with 30% glacial acetic acid and quantified through measuring the absorbance at 550 nm. The data shown are the summary of those from four individual experiments that were performed in technical triplicate, with error bars representing standard deviations. Lact, lactate; Surv, Survanta. Statistical analysis was performed using the MOPS-lactate condition of each strain as the comparator via one-way analysis of variance and Dunnett's multiple-comparison test for K. pneumoniae MGH 78578 and two-way analysis of variance with Sidak's multiple-comparison test for the KPPR1 WT and KPPR1 ΔmrkABC. Statistical significance is specified as follows: ****, P < 0.0001.