Stability and activity of TG25P phage in control of Aeromonas hydrophila in striped catfish pond water

Introduction: Striped catfish (Pangasianodon hypohthalmus) is a native freshwater fish species in the Mekong Delta, Vietnam, and significantly contributes to national aqua exports. Currently, however, the sustainable development of striped catfish farming is being affected by bacterial pathogen infections, of which hemorrhagic septicemia caused by Aeromonas hydrophila bacteria is one of the most common diseases. Methods: In this study, the stability of TG25P and CT45P phages to factors such as temperature, pH, and organic solvents was investigated, with the stability of TG25P being found to be higher than that of CT45P. Results: The activity of TG25P was retained to approximately 90% and 80% at 37oC and 50oC for 1 h, respectively. Its activity was maintained to greater than 80% at pH 5-9 for 24 h and approximately 90-100% in organic solvents, such as chloroform or diethyl ether, for 1 h. In addition, the stability and activity of TG25P for the control of A. hydrophila in striped catfish pond water was also evaluated for 48 h. Conclusion: TG25P was found to be highly applicable in the creation of low-cost phage-containing products for the prospective application of phage therapy in prevention and treatment of hemorrhagic septicemia in striped catfish.