The development of phage libraries is vital for phage-based applications and to further the understanding of phage–host interactions. However, phage isolation from environmental samples on a large scale is resource-intensive.
Methods:
To optimize the detection of phages from environmental water samples with low phage concentrations, we assessed and optimized a small-volume enrichment method using the important fish pathogen Flavobacterium psychrophilum as a target host.
Results:
The 96-well plate enrichment assay demonstrated phage activity in samples with initial phage concentrations of a single plaque-forming unit (PFU) per well, and the overall detection limit of the method was 0.011 PFU mL−1 in the water sample. For phage concentrations >10 PFU, the phage concentration in the sample could be predicted from optical density inhibition during incubation. When applied to 45 water samples collected from a recirculating aquaculture system, phages were detected in 36 of the samples.
Conclusion:
While this method provides resource-efficient means to isolate phages from aquatic environments, phage–host system-dependent variations are shown, and optimization for other phage–host systems is recommended.
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