Application of novel lytic bacteriophages to control Vibrio parahaemolyticus load in seafood

Consumption of seafood contaminated with Vibrio parahaemolyticus leads to acute gastroenteritis. Bacteriophages are considered the biological enemies of bacteria, present in the same ecosystem where the bacteria are found, and their applicability in reducing pathogens in the food industry cannot be overlooked. Hence, we aimed to isolate novel lytic bacteriophages and evaluate their potential application to reduce the load of V. parahaemolyticus in seafood. Eight lytic phages were isolated during the study, showing a broad range of activity. Among them, phage VpPH showed the maximum host range, with a titer of 2 × 10¹⁰ plaque-forming units per ml (PFU/ml). Results showed that 200 µl of phage (2 × 10¹⁰ PFU/ml) was adequate to reduce V. parahaemolyticus counts by 4 log units within 16 h. Lytic activity of phage was maximum within 4 h of the experiment, and the application of double doses at 4 h intervals was effective in reducing V. parahaemolyticus. The number of V. parahaemolyticus cells in spiked seafood, enumerated by plating followed by colony hybridization using tlh probes, was decreased significantly after the addition of the phage. The current study showed promising results regarding the application of lytic bacteriophages to conrol V. parahaemolyticus in laboratory-scale, which can be further scaled up for large-scale application in the food industry.