FIG. 2.

In situ epifluorescent image of biofilms on the surface of pipes from one of the sites in Latvia (A) and England (B). The arrows point to E. coli cells. FISH was performed directly on the surfaces of the pipes that were exposed to drinking water for more than 25 years. Combined photographs of E. coli and all bacteria detected with DAPI in blue filter (excitation, 360/20 nm; emission, >425 nm) are shown in panel A. In panel B, photographs of E. coli detected by FISH in yellow filter (Y3: excitation, 535/50 nm; emission, 610/75 nm) are shown. Bar, 10 μm.