Reduction of Vibrio alginolyticus Contamination in Raw Seafood by a Novel Phage vB_Va_ZWPVA056

Vibrio alginolyticus is a foodborne pathogen commonly found in seawater and seafood products, including shellfish, fish, and shrimp. Consumers who eat contaminated sashimi or undercooked seafood may develop gastroenteritis, and in severe cases, wound infections or sepsis. Traditional antimicrobial methods, such as antibiotics and chemical disinfectants, can easily induce drug resistance and may compromise the quality of seafood. This study isolated a bacteriophage (phage) of Vibrio alginolyticus, named vB_Va_ZWPVA056, from an aquaculture tank during a disease outbreak affecting sea cucumbers. A one-step growth curve revealed a 5-min latency period and a lytic titer of 153 PFU/cell. The phage exhibited remarkable stability, maintaining activity over a temperature range of 4-50 ℃ and a broad pH range of 3-10. Whole-genome sequencing revealed a double-stranded DNA genome of 76,085 bp, encoding 102 putative proteins. Crucially, bioinformatics analysis confirmed the absence of virulence, lysogeny, or antibiotic resistance genes, underscoring its safety for biocontrol applications. The phage's practical efficacy was evaluated by simulating Vibrio alginolyticus contamination on high-value seafood, including prawns, abalone, grouper, squid, and salmon. Phage treatment at MOIs of 1 and 0.1 significantly suppressed bacterial growth, achieving a maximum reduction of 1.84 log CFU/mL on Prawns after 12 h at 4 °C. After 24 h, the phage effectively reduced viable bacterial counts across all five tested seafood types at both 4 °C and 28 °C. These findings advocate for vB_Va_ZWPVA056 as a targeted biocontrol agent to suppress Vibrio alginolyticus populations in raw and ready-to-eat seafood throughout the supply chain, offering a sustainable strategy to mitigate microbial risks and improve product safety without compromising quality.