Abstract: The photodynamic inactivation of common pathogenic (Vibrio parahaemolyticus) and spoilage (Shewanella putrefaction) bacteria in aquatic products was investigated using curcumin as a photosensitizer. Viable cell counts, cell regrowth capacity, cell surface morphology, reactive oxygen species (ROS) level, biofilm biomass and cell viability were detected before and after photodynamic treatment, and the structural parameters of biofilms were further analyzed. The results showed that when the final concentration of curcumin was 3.0 or 10 μmol/L, and the illumination time was 8 min, the colony number of V. parahaemolyticus and S. putrefaciens were reduced by more than 7 (lg(CFU/mL)). The antibacterial mechanism was by producing a large amount of ROS, leading to the breakdown of the bacterial cell wall and eventually cell lysis and death. In addition, when the illumination time was 60 min, the eradication rates of V. parahaemolyticus and S. putrefaciens biofilms were about 70% and 62% for curcumin concentrations of 30 and 50 μmol/L, respectively. This study may provide new ideas for the design of a new photodynamic technology (PDT) for use in the food industry.

Key words: photodynamic technology; curcumin; Vibrio parahaemolyticus; Shewanella putrefaciens; biofilm