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Open Access Research article

The culturable intestinal microbiota of triploid and diploid juvenile Atlantic salmon (Salmo salar) - a comparison of composition and drug resistance

Leon Cantas12*, Thomas WK Fraser3*, Per Gunnar Fjelldal4, Ian Mayer3 and Henning Sørum1

Author Affiliations

1 Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, NO-0033 Oslo, Norway

2 Norwegian Food Safety Authority, District Office for Romerike, NO-2381 Brumunddal, Norway

3 Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, NO-0033 Oslo, Norway

4 Institute of Marine Research (IMR), Matre Research Station, NO-5984 Matredal, Norway

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BMC Veterinary Research 2011, 7:71  doi:10.1186/1746-6148-7-71

Published: 17 November 2011



With the increased use of ploidy manipulation in aquaculture and fisheries management this investigation aimed to determine whether triploidy influences culturable intestinal microbiota composition and bacterial drug resistance in Atlantic salmon (Salmo salar). The results could provide answers to some of the physiological differences observed between triploid and diploid fish, especially in terms of fish health.


No ploidy effect was observed in the bacterial species isolated, however, triploids were found to contain a significant increase in total gut microbiota levels, with increases in Pseudomonas spp., Pectobacterium carotovorum, Psychrobacter spp., Bacillus spp., and Vibrio spp., (12, 42, 9, 10, and 11% more bacteria in triploids than diploids, respectively), whereas a decrease in Carnobacterium spp., within triploids compared to diploids was close to significant (8% more bacteria in diploids). With the exception of gentamicin, where no bacterial resistance was observed, bacterial isolates originating from triploid hosts displayed increased resistance to antibacterials, three of which were significant (tetracycline, trimethoprim, and sulphonamide).


Results indicate that triploidy influences both the community and drug resistance of culturable intestinal microbiota in juvenile salmon. These results demonstrate differences that are likely to contribute to the health of triploid fish and have important ramifications on the use of antibacterial drugs within aquaculture.