Reversible mutations in gliding motility and virulence genes: A flexible and efficient phage defence mechanism in Flavobacterium psychrophilum.

Flavobacteria are among the most important pathogens in freshwater salmonid aquaculture worldwide. Due to concerns regarding development of antibiotic resistance, phage therapy has been proposed as a solution to decrease pathogen load. However, application of phages is challenged by the development of phage resistance, and knowledge of the mechanisms and implications of phage resistance is therefore required.

Comparative Genomic Analyses of Isolates Reveals New Putative Genetic Determinants of Virulence Traits.

The fish pathogen is currently one of the main pathogenic bacteria hampering the productivity of salmonid farming worldwide. Although putative virulence determinants have been identified, the genetic basis for variation in virulence of is not fully understood. In this study, we analyzed whole-genome sequences of a collection of 25 isolates from Baltic Sea countries and compared genomic information with a previous determination of their virulence in juvenile rainbow trout.

Bacteriophage Resistance Affects Flavobacterium columnare Virulence Partly via Mutations in Genes Related to Gliding Motility and the Type IX Secretion System.

Increasing problems with antibiotic resistance have directed interest toward phage therapy in the aquaculture industry. However, phage resistance evolving in target bacteria is considered a challenge. To investigate how phage resistance influences the fish pathogen Flavobacterium columnare, two wild-type bacterial isolates, FCO-F2 and FCO-F9, were exposed to phages (FCO-F2 to FCOV-F2, FCOV-F5, and FCOV-F25, and FCO-F9 to FCL-2, FCOV-F13, and FCOV-F45), and resulting phenotypic and genetic changes in bacteria were analyzed.

Genome-informed approach to identify genetic determinants of Flavobacterium psychrophilum phage susceptibility.

The fish pathogen Flavobacterium psychrophilum infects farmed salmonids worldwide, and application of bacteriophages has been suggested for controlling disease outbreaks in aquaculture. Successful application of phages requires detailed knowledge about the variability in phage susceptibility of the host communities. In this study, we analysed the genetic diversity of F.

Phage-Mediated Control of in Aquaculture: Experiments to Compare Delivery Methods.

Phage-based approaches have gained increasing interest as sustainable alternative strategies to antibiotic treatment or as prophylactic measures against disease outbreaks in aquaculture. The potential of three methods (oral, bath, and injection) for delivering a two-component phage mixture to rainbow trout fry for controlling infections and reduce fish mortality was investigated using bacteriophages FpV4 and FPSV-D22. For the oral administration experiment, bacteriophages were applied on feed pellets by spraying (1.

Bacteriophages as Biocontrol Agents for Biofilms and Rainbow Trout Infections.

Bacteriophages (phages) have been proposed as an alternative to antibiotics and surface disinfectants for treatment of biofilms and fish infections in aquaculture settings. The aim of the study was to estimate the minimal phage:host ratio (PHR) required for the control of biofilm formation and mortalities caused by in experimentally infected fish. cells in different stages of biofilm formation were exposed to the lytic phage FPSV-D22 at different PHRs.

Multilocus sequence typing identifies epidemic clones of Flavobacterium psychrophilum in Nordic countries.

Flavobacterium psychrophilum is the causative agent of bacterial cold water disease (BCWD), which affects a variety of freshwater-reared salmonid species. A large-scale study was performed to investigate the genetic diversity of F. psychrophilum in the four Nordic countries: Denmark, Finland, Norway, and Sweden.

Structure of Flavobacterium psychrophilum populations infecting farmed rainbow trout Oncorhynchus mykiss .

Flavobacterium psychrophilum isolated from rainbow trout Oncorhynchus mykiss suffering from bacterial cold-water disease (BCWD) can dissociate into 2 morphological colony types, rough (R) and smooth (S). However, the presence of the 2 morphotypes in disease outbreaks has not yet been investigated thoroughly. We examined the occurrence of R and S morphotypes in rainbow trout from BCWD outbreaks and in unfertilized eggs from a hatchery.