FIG 6.

Single-well overview images of E. coli isolates showing different strengths of biofilm formation. Fluorescence images were captured after 48 h of biofilm formation in respective media and staining with SYTO 9. (A) The positive control E. coli MG1655 F′Tet ΔtraD in LB medium exhibiting strong biofilm formation (relFI, 0.4398). (B) One HFEC isolate in M63 medium displaying an even biofilm in the center and a much more pronounced biofilm along the edge of the well (relFI, 0.1102). (C) One UPEC isolate in M63 medium forming a flat and evenly distributed biofilm in the well (relFI, 0.0369). (D) One EAEC isolate in BHI medium showing the characteristic biofilm consisting of thick bacterial aggregates (relFI, 0.2763).