The complete genome sequence and analysis of vB_VorS-PVo5, a Vibrio phage infectious to the pathogenic bacterium Vibrio ordalii ATCC-33509

Isolation, characterization, and complete genome sequence of vibrio phage KIT04, a novel lytic phage of the subfamily ermolyevavirinae

Vibrio phage KIT04 was isolated from muscle tissue samples collected from a local market in Vietnam. KIT04 is a lytic phage that is specific to Vibrio parahaemolyticus. The one-step growth curve determined the burst size and latent period of 0.01 multiplicity of infection KIT04 in V. parahaemolyticus as approximately 156 plaque-forming units/bacterium and 45 min, respectively. Vibrio phage KIT04 has an approximately 76.4 ± 4.5 nm diameter icosahedral head and a tail length of approximately 159.5 ± 16.6 nm long tail. KIT04 significantly reduced V. parahaemolyticus ATCC 17802 in vitro. Complete genome analysis showed that KIT04 had a 114,933 bp dsDNA genome with 40.24% G + C content and 160 open reading frames (ORFs). However, the phage genome contained 24 tRNAs and no lysogeny-related genes. Moreover, five of the 160 ORFs encoded unique hypothetical proteins, indicating that KIT04 is a novel phage. Genomic comparison indicated that KIT04 is closely related to the Vibrio phages pVp-1 and VPT02. Further, phylogenetic analysis of the major tail proteins and whole genome supported the KIT04 classification into the subfamily Ermolyevavirinae. Our study describes a new candidate phage that could be used as a bioagent for controlling Vibrio pathogens.

Phage Therapy as a Focused Management Strategy in Aquaculture

Therapeutic bacteriophages, commonly called as phages, are a promising potential alternative to antibiotics in the management of bacterial infections of a wide range of organisms including cultured fish. Their natural immunogenicity often induces the modulation of a variated collection of immune responses within several types of immunocytes while promoting specific mechanisms of bacterial clearance. However, to achieve standardized treatments at the practical level and avoid possible side effects in cultivated fish, several improvements in the understanding of their biology and the associated genomes are required. Interestingly, a particular feature with therapeutic potential among all phages is the production of lytic enzymes. The use of such enzymes against human and livestock pathogens has already provided in vitro and in vivo promissory results. So far, the best-understood phages utilized to fight against either Gram-negative or Gram-positive bacterial species in fish culture are mainly restricted to the Myoviridae and Podoviridae, and the Siphoviridae, respectively. However, the current functional use of phages against bacterial pathogens of cultured fish is still in its infancy. Based on the available data, in this review, we summarize the current knowledge about phage, identify gaps, and provide insights into the possible bacterial control strategies they might represent for managing aquaculture-related bacterial diseases.

Characterization of the Bacteriophage vB_VorS-PVo5 Infection on Vibrio ordalii: A Model for Phage-Bacteria Adsorption in Aquatic Environments

A mathematical first-order difference equation was designed to predict the dynamics of the phage-bacterium adsorption process in aquatic environments, under laboratory conditions. Our model requires knowledge of bacteria and bacteriophage concentrations and the measurements of bacterial size and velocity to predict both the number of bacteriophages adsorbed onto their bacterial host and the number of infected bacteria in a given specific time. It does not require data from previously performed adhesion experiments. The predictions generated by our model were validated in laboratory. Our model was initially conceived as an estimator for the effectiveness of the inoculation of phages as antibacterial therapy for aquaculture, is also suitable for a wide range of potential applications.

A rapid and simple protocol for the isolation of bacteriophages from coastal organisms

This work details a protocol for recovering bacteriophages from intertidal sessile mussels and testing their lytic activity against pathogenic bacteria. Although bacteriophages were highly abundant in coastal filter-feeding organisms, they were not detectable in the surrounding water column. This difference reflects the high filtering rate of the mussels, which capture and concentrate high amounts of bacteria, generating an ideal environment for bacteriophages. We validated the protocol providing a mean concentration of 4E + 04 PFU mL^-1 lytic bacteriophages for the fish-pathogen bacterium Vibrio ordalii. We suggest that this method has particular utility for the recovery of bacteriophages for use as natural antimicrobial agents in aquaculture.