A broad-spectrum vibriophage with potential for phage therapy against Vibrio alginolyticus in shrimp aquaculture

Phage therapy, a promising alternative to antibiotics, has gained traction in aquaculture for combating bacterial diseases. This study investigated the potential application of a lytic phage, vB_ValS_R12Z (R12Z), against Vibrio alginolyticus ATCC 17749^T, in aquaculture by characterizing its biological and genetic properties. Phage R12Z displayed a siphovirus morphotype, characterized by a short latent period of 35 min and a large burst size of 105 ± 27 plaque forming units (PFU) per infected cell. Intergenomic similarity analysis revealed that R12Z belongs to the same species within the genus Mardecavirus as phages KF6 and HCMJ, with no antibiotic resistance factor-related genes or virulence factors detected. Host range experiments demonstrated that R12Z is capable of infecting at least three Vibrio species, including seven strains of V. alginolyticus, one strain of V. parahaemolyticus, and one strain of V. natriegens. The strong lytic capacity and high bacteriostatic capability of R12Z were observed with an average bacteriolytic efficiency exceeding 75 % across all multiplicities of infection (0.001–10). In addition, R12Z showed robust environmental stability, enduring pH levels between 4 and 11, and temperatures spanning 4 °C–50 °C. R12Z showed effective protection of shrimp postlarvae from V. alginolyticus, resulting in higher survival rates. Phage R12Z is therefore a potential therapeutic agent against vibriosis in aquaculture, offering promising prospects for disease management in aquatic settings.