Isolation and characterization of a wide-spectrum bacteriophage ФV170 lysing Vibrio alginolyticus

Abstract:

[Background] Vibrio alginolyticus, one of the most important opportunistic pathogens, can cause significant morbidity, mortality and economic losses during shrimp aquaculture. At present, phage therapy acts as an alternative sanitizing agent to control V. alginolyticus. [Objective] To isolate and characterize phage ФV170 lysing V. alginolyticus for the application of the phage to control aquatic animal diseases. [Methods] V. alginolyticus V170 was used as the host strain to isolate phage from Penaeus vannamei aquaculture water. Characterization was done by transmission electro-microscopy, optimal multiplicity of infection, one-step growth curve, lysis spectrum detection, thermal stability, and sensitivity to chloroform. The analyses of phage genome were based on enzyme digestion methods. [Results] A broad-spectrum lytic bacteriophage ФV170 was isolated and the plaques were neat and transparent, with a diameter of 1.5 mm at 12 h. The identification results of transmission electron microscopy (TEM) showed that its head had a stereosymmetric structure of the quasi-diaphedron, with a diameter between 60 nm and 65 nm, and its tail was 65 nm to 75?nm long and 14 nm to 18 nm wide. The nucleic acid type was dsDNA and the genome about 45 kb. Besides, it was not sensitive to chloroform. In conclusion, bacteriophage ФV170 belongs to Caudovirales and Myoviridae. The bacteriophage V170 can lyse 7 of 15?strains of Vibrio alginolyticus, possessing a broad host spectrum within the species. The optimal multiplicity of infection (MOI) was 0.01. One-step growth curve shows that the incubation period of ФV170 was 10?min and the amount of lysis was 101.3. Phage ФV170 was sensitive above 65 °C. [Conclusion] A lytic bacteriophage was isolated with potential functions to treat alginolyticosis in marine aquaculture.