Isolation and characterization of five lytic bacteriophages infecting a Vibrio strain closely related to Vibrio owensii

Vibrio owensii is a potential bacterial pathogen in marine aquaculture system. In this study, five lytic phages specific against Vibrio strain B8D, closely related to V.owensii, were isolated from seawater of an abalone farm. The phages were characterized with respect to morphology, genome size, growth phenotype, as well as thermal, and pH stability. All phages were found to belong to the family Siphoviridae with long noncontractile tails and terminal fibers. Restriction analysis indicated that the five phages were dsDNA viruses with molecular weights ranging from c. 30 to 48kb. One-step growth experiments revealed that the phages were heterogeneous in latent periods (10-70min), rise periods (40-70min), and burst sizes [23-331 plaque-forming units (PFU) per infected cell] at the same host strain. All phages were thermal stable and were tolerant to a wide range of pH. The results indicated that these phages could be potential candidates of a phage cocktail for biological control of V.owensii in aquaculture systems.