Formation of biofilms of the salmon pathogen Flavobacterium psychrophilum in differents surfaces using the CDC biofilm reactor

Aquaculture settings present a number of surfaces that can potentially act as a reservoir for Flavobacterium psychrophilum, resulting in a serious threat to the health of farmed salmonids. The aim of this study was to employ the CDC Biofilm Reactor to evaluate the capacity of F. psychrophilum to form biofilms on stainless steel, polystyrene, polyurethane, and polycarbonate. Scanning electron microscopy and confocal laser scanning microscopy were used to assess biofilm formation, while epifluorescence and qPCR methods were effectively used to determine cell contents. After a 72 h incubation period, F. psychrophilum had formed mature biofilms composed by dense, multilayered clusters of short bacilli on stainless steel, polystyrene, and polycarbonate. Nevertheless, biofilms formed on stainless steel presented a significantly higher cell density than those formed on polyurethane. Biofilm growth was poor on polyurethane surfaces. These findings will facilitate the design of appropriate guidelines for more efficiently managing F. psychrophilum and controlling the persistence of this pathogen in fish-farming environments.