Characterization and genome analysis of a novel phage BP15 infecting Vibrio parahaemolyticus

Vibrio parahaemolyticus is pathogenic to both humans and marine animals. Antimicrobial-resistant (AMR) bacteria have been reported to cause mortalities in shrimp, with phage therapy presenting an alternative and eco-friendly biocontrol strategy for controlling bacterial diseases. Therefore, this study aimed to isolate and characterize phages for their applicability in lysing Vibrio parahaemolyticus. A novel phage vB_VpaS_BP15 (BP15) belonged to the subfamily Queuovirinae with an icosahedral head measuring 69.11 ± 5.38 nm in length and 65.40 ± 6.89 nm in width, and a non-contractile sheathed tail measuring 139.81 ± 14.79 nm. The one-step growth curve indicated a latent period of 30 min and a burst size of 120 PFUs per cell. Phage BP15 exhibited tolerance to a range of temperatures and pH values. Infection dynamic curves demonstrated that BP15 was highly effective against BCRC12959 at MOIs ranging from 0.01 to 10; even at a low multiplicity of infection (MOI) of 0.001, BP15 still caused growth retention. Phage BP15 possessed a circular double-stranded DNA of 59,584 bp with a G + C content of 46.7% and lacked tRNA genes, virulence genes, and lysogeny genes. These findings highlight the promising potential of phage BP15 as a biocontrol agent against Vibrio parahaemolyticus in Taiwan.