Phage-Based Approaches for Potential Integration into Bivalve Depuration Systems

The rising global demand for bivalves and declining water quality is placing increasing pressure on depuration facilities to ensure product safety and quality, leading to extended processing times and increased energy consumption. Bacteriophages (phages) offer a low-cost, environmentally friendly, and highly specific approach that may enhance depuration efficiency. In this study, we evaluated a phage cocktail targeting Escherichia coli, Aeromonas hydrophila, Salmonella enterica serovar Typhimurium, and Vibrio parahaemolyticus to improve depuration at laboratory-scale using cockles (Cerastoderma edule). Three depuration experiments of 12 h were performed: (i) cockles artificially contaminated with E. coli or V. parahaemolyticus; (ii) cockles inoculated with all four bacteria; and (iii) naturally contaminated cockles. Phages reduced bacterial loads by 1.62 and 1.61 Log colony forming units per gram (CFU/g) for E. coli and V. parahaemolyticus, respectively. In experiments using the four bacterial strains, reductions of ~1.00 Log CFU/g were observed only at higher doses. This phage dose also caused bacterial reduction in naturally harvested animals by 1.00–1.28 Log CFU/g. Our findings suggest that, under phage selective pressure, bacteria may be released from bivalves, probably as result of phage-induced disruption of biofilms, destabilising bacterial colonisation. Therefore, bivalve exposure to phage doses prior to water disinfection can complement the depuration treatment, increasing decontamination efficiency and enhancing food safety.