FIG. 3.

Epifluorescence image of metabolically active E. coli in biofilm sample from water distribution networks in France. Biofilm was removed from a cast iron coupon (T2; retention time, 119 days) by sonification and subjected to resuscitation procedure for 8 h in 50% R2A media with pipemidic acid. The total bacteria number was detected with DAPI (A) in blue filter (excitation, 360/20 nm; emission, >425 nm) and E.coli detected with FISH methods in yellow filter (Y3: excitation, 535/50 nm; emission, 610/75 nm) (B). The arrows point to an elongated E. coli cell. Bar, 10 μm.