Salmon microbiota phage therapy. Page therapy against Flavobacterium columnare does not disturb the microbiota of Atlantic salmon (Salmo salar) yolk sac fry rearing water in the absence of the host

Atlantic salmon yolk sac fry were conventionalized and raised at 6°C until 6 weeks post hatching. The temperature was increased to 10°C and the fish were then either exposed to the bacterial pathogen Flavobacterium columnare or were left unchallenged. Both groups were then either treated with the antibiotic oxytetracycline or with a bacteriophage against F. columnare or were left untreated. Water samples were taken right before infection, 12 h, 2 days and 10 days after infection. DNA was extracted from the water samples and the V3+V4 region of the bacterial 16S rRNA gene was amplified and was sequenced on an Illumina MiSeq run. The resulting sequencing data were analyzed on how the different treatments affected the microbial water communities, both in the presence and the absence of the pathogen F. columnare.