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Vibriophages: saviour or sinner in aquaculture

Principal Supervisor: Dr Andrew Millard, Department of Infection, Immunity and Inflammation

Co-supervisor: Professor Martha Clokie

PhD project title: Vibriophages: saviour or sinner in aquaculture

University of Registration: University of Leicester

Project outline:

Vibrios are a diverse genera of Gram-negative bacteria that are widespread in the marine environment. The most well-known Vibrio species is Vibrio cholerae, as the causative agent of cholera. However, there are many other Vibrio spp that are also harmful and know to be pathogenic including Vibrio parahaemolyticusand Vibrio vulnificus. Both of these organisms are opportunistic human pathogens and are linked to seafood related deaths. In addition Vibrio angulliarium, Vibriosalmonicidaand Vibrio damselaeare the causative agents of Vibriosis in aquaculture, which can result in very high mortality rates in fish farming.

Bacteriophages (viruses capable of infecting bacteria) offer the potential as both agents to control Vibriosis (lytic phages) and to increase the virulence of Vibrios (temperate bacteriophages) . To combat Vibrosis in aquaculture, is necessary to understand how both temperate phages contribute to virulence and if lytic phages offer an alternative to traditional antibiotics. Recently we have predicted a huge diversity of temperate phages within the genomes of Vibrio spp, many of which carry virulence genes. Due the vast diversity of phages, predicting the exact region of prophages in bacterial genomes is notoriously difficult.

In this PhD the student will further characterise prophages within Vibrio spp and begin to evaluate the effectiveness of lytic phages to combat Vibriosis.

Objectives:

  1. Begin to induce temperate phages from selected Vibrios, to experimentally confirm bioinformatics predictions. Use the results of experimental validations to improve the models for predicting prophages
  2. Generate Vibrio mutants that have been cured of “prophages” and determine if virulence is decreased
  3. Isolate lytic phages against Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio angulliarium, Vibriosalmonicidaand Vibrio damselae.
  4. Determine if lytic phages can be used to reduce Vibriosis in a model system of fish larvae.

BBSRC Strategic Research Priority: Food Security

Techniques that will be undertaken during the project: Food Security

  • Microbiology – Phage isolation, culturing bacteria,
  • Molecular biology – construction of Vibrio mutants
  • High-throughput sequencing – sequencing of induced supernatants to identify temperate phage – bioinformatics analysis of this
  • Bioinformatics – prediction of prophage within Vibrio genomes. Refinement of algorithms to predict prophages in large datasets (Bioinformatics and quantitative skills )

Contact: Dr Andrew Millard, University of Leicester