Edible bacteriophage based antimicrobial coating on fish feed for enhanced treatment of bacterial infections in aquaculture industry

As the fastest growing food-producing industry in the world, aquaculture industries frequently suffer from the outbreaks of various bacterial diseases. There is a need to develop alternatives to antibiotics to address the challenge of bacterial infections without using conventional antibiotics. This study developed a bacteriophage based edible antimicrobial coatings on fish feed, providing an effective biological control strategy for treating fish and human pathogens in an aquaculture system. The edible whey protein isolate (WPI) coatings were effective in enhancing loading of phages on fish feed pellets and reducing the loss of phage activity during storage of feed. The feasibility of both dip coating and air-brush spray coating methods were demonstrated in this study. The edible coatings decreased the release of phages in salt water by > 1 log PFU/pellet after 2-h exposure as compared to control coatings on feed without the biopolymer coatings. The simulated gastric-intestinal digestion assay demonstrates that this coating provides enhanced stability of phages in a simulated gastric environment and a significant bacterial reduction (3-5 logs of target bacteria) in a simulated intestinal digestion. These antimicrobial activity results were demonstrated using a model bacterium (E. coli) and a fish pathogen (Vibrio spp.). Overall, the results show that phage incorporated WPI coatings on fish feed can be an effective approach for enhancing the treatment fish infections, reducing the risk of antibiotic resistance in aquaculture environment, and improving the safety and sustainability of aquaculture industry.