Combating bacterial cold water disease in aquaculture: Bacteriophage infectivity across time

Student: 
Kiano Gorissen

Bacterial cold water disease is a disease commonly encountered in aquaculture farms, including trout fish farms. The causative agent Flavobacterium psychrophilum has been linked to high mortality rates in fry fish of Rainbow trout. Currently treatment is achieved with antibiotics. However, the spread of antibiotic resistant genes has increased the demand for alternative treatment methods. Bacteriophage therapy is once such methods, potentially providing a long term solution to the disease. During this thesis 6 new bacteriophages were isolated, purified and characterised based on host range. The host range of these phages were compared to phages isolated in 2023 and found to be more effective against bacterial strains isolated during the same time period or shortly after. Three clusters of phages were identified, mainly defined by time of isolation of the phages. However, one cluster contained both new and old phages. For DNA extraction, a 10 ml starting volume was identified as  the ideal volume for extraction.