Phage VBY outperforms ozone and UV in aquaculture tailwater disinfection

Researchers report the first targeted phage-based disinfection of aquaculture tailwater, using a newly isolated bacteriophage to cut multidrug-resistant Vibrio parahaemolyticus and its resistance genes while preserving water quality. The result could offer a more selective alternative to ozone and UV for recycling aquaculture water and reducing the spread of antibiotic resistance.

Why it matters: - Aquaculture tailwater can carry multidrug-resistant pathogens and antibiotic resistance genes that threaten food safety and public health. - A targeted disinfection method could reduce resistant bacteria without the collateral damage caused by ozone, UV or chlorination. - The approach could help make recycled aquaculture water safer while preserving the microbial balance in treatment systems.

What happened: - Researchers isolated a novel lytic bacteriophage, VBY, from coastal aquaculture tailwater and tested it against multidrug-resistant Vibrio parahaemolyticus. - The team reported the findings in ENGINEERING Environment, DOI 10.1007/s11783-026-2279-5. - In real tailwater treatment systems, VBY reduced bacterial loads by 5.5 logarithmic units over 72 hours. - VBY also suppressed four key antibiotic resistance genes by 4 to 6 logs over the same period. - The phage outperformed ozone and ultraviolet disinfection while preserving water quality.

The details: - VBY is a Caudoviricetes virus with an icosahedral capsid 113 nanometers wide and a long, non-contractile tail 378 nanometers long. - Its genome is a 30,247-base-pair circular double-stranded DNA molecule with 42 open reading frames. - The phage genome contains no virulence factors or antibiotic resistance genes. - VBY stayed active across a pH range of 5 to 11 and at temperatures up to 60°C. - The phage was sensitive to UV irradiation. - Host-range tests showed VBY was highly specific to V. parahaemolyticus strains. - VBY showed no lytic activity against other aquatic microbes, including diverse Vibrio species, Aeromonas spp., Klebsiella pneumoniae, Escherichia coli or beneficial Nitrospina gracilis. - In pilot-scale tailwater systems, phage treatment kept dissolved oxygen stable and prevented ammonia, nitrite, total organic carbon and dissolved organic carbon buildup. - The study says conventional chemical disinfection can generate harmful by-products, damage aquatic microbial communities and fail to remove ARGs carried by bacteria or bacterial debris. - The research team included scientists from the Yantai Institute of Coastal Zone Research, the University of Chinese Academy of Sciences, Harbin Engineering University and the University of Florida.

Between the lines: - The result suggests phage therapy may be useful as a precision water-treatment tool, not just a pathogen-control method. - Because ozone and UV can trigger stress responses that may increase ARG release or horizontal transfer, a phage that kills the host without carrying resistance genes may reduce that risk. - The study points to a practical niche for VBY as a pretreatment step before terminal UV or chlorine disinfection. - The work is framed as the first demonstration of phage-mediated disinfection for targeted removal of MDR pathogens and associated ARGs from recycled tailwater.

What's next: - Researchers suggest VBY could be integrated into treatment flows ahead of UV or chlorine in practical aquaculture systems. - The phage’s stability in aquaculture-relevant pH and temperature ranges supports storage and transport. - The broader test will be whether phage-based disinfection scales reliably in commercial tailwater recycling systems. - The funding came from the National Natural Science Foundation of China, the National Key R&D Program of China and the Taishan Scholars Program.