Isolation and Identification of a Vibrio alginolyticus Bacteriophage Va2001 and Its Application

In order to develop the cleaning agent for Vibrio alginolyticus in aquatic products, about 60 pieces of seafood and sewage in their breeding environment were collected from aquatic product market and farmer’s market in Jinzhou City, Bijiashan sea area, supermarkets, an aquaculture farm in Huludao City, and a breeding farm in Anshan City, etc. A virulent phage strain, named Va2001, was obtained by isolating and purifying with double-layer plate method. The biological characteristics of Va2001, such as the lysis spectrum, optimal multiplicity of infection, one-step growth curve, temperature, and pH stability, were studied. In addition, the effect of bacteriophages clearing V. alginolyticus was determined in the oyster infection model. The results showed that the phage Va2001 belongs to the Podoviridae family of order Caudovirales. Va2001 had a narrow lysis spectrum, with a lysis rate of 32%. The optimal multiplicity of infection was 0.0001 and the incubation period was about 20 min. The lytic period was 100 min and the average burst size was 274 PFU/cell. The activity was stable in the range of 4~60 ℃ and pH4~9. The results of the cleaning test using oysters as the infection model showed that the bacteriophage Va2001 could inhibit the growth of V. alginolyticus in the breeding environment and reduce the content of V. alginolyticus in oysters. When the breeding time was extended to 72 hours, the number of V. alginolyticus in the experiment group decreased by about 2 lg. The results of this study indicate that the bacteriophage Va2001 has good application prospects and can be used as a new biological cleaning agent of V. alginolyticus in seafood.