Biofilm-forming capability and susceptibility to disinfectants among bacterial isolates from seafood processing in Québec

Fish and seafood processing faces persistent microbial contamination issues, due largely to biofilm formation on equipment and product contact surfaces, despite sanitation procedures. In this study, the bacterial diversity found on production lines processing shrimp, smoked salmon (artisanal and industrial-scale), snow crab and lobster was evaluated in terms of biofilm-forming ability and resistance to two conventional and two alternative disinfection treatments. From a total of 105 surfaces sampled after sanitation, 472 bacterial isolates were obtained, representing 53 genera, primarily Pseudomonas , Aeromonas , and Acinetobacter . While most isolates produced weak biofilms, moderate to strong biofilm producers were mainly Pseudomonas (43 %), Aeromonas (22 %), and Acinetobacter (10 %). Nine representative isolates were tested against peracetic acid. Peracetic acid (100 ppm) reduced viable counts by > 3 log cfu/mL in four isolates, although two showed marked resistance (<1 log reduction). Sodium hypochlorite (70 ppm) was effective against five isolates, while one was resistant. Reuterin (258 mM) proved ineffective against all isolates, whereas pulsed light (11.52 J/cm 2 ) achieved reduction greater than 3 log for most strains. These results highlight the persistence of biofilm-forming bacteria after sanitation and demonstrate that resistance varies across genera and treatments. In particular, Pseudomonas and Acinetobacter emerge as key genera capable of withstanding conventional disinfectants, emphasizing the need to optimize both chemical and non-chemical disinfection strategies to improve hygiene in seafood processing. • A wide diversity of microorganisms was found on fishery surfaces in Quebec. • 41 % of the analyzed strains demonstrated potential to form biofilms. • Pseudomonas spp. was identified as the main biofilm-forming genus across samples. • Disinfectant efficiency varied depending on strain type and exposure conditions.