Development of a bacterial challenge test for gnotobiotic sea bass (Dicentrarchus labrax) larvae

Authors

  • K. Dierckens,

    Corresponding author
    1. Laboratory of Aquaculture & Artemia Reference Center and
    2. Laboratories that belong to the UGent Aquaculture R&D Consortium, Ghent University, Gent, Belgium.
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  • A. Rekecki,

    1. Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
    2. Laboratories that belong to the UGent Aquaculture R&D Consortium, Ghent University, Gent, Belgium.
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  • S. Laureau,

    1. Ecloserie Marine de Gravelines, Gravelines, France.
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  • P. Sorgeloos,

    1. Laboratory of Aquaculture & Artemia Reference Center and
    2. Laboratories that belong to the UGent Aquaculture R&D Consortium, Ghent University, Gent, Belgium.
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  • N. Boon,

    1. Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Gent, Belgium.
    2. Laboratories that belong to the UGent Aquaculture R&D Consortium, Ghent University, Gent, Belgium.
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  • W. Van den Broeck,

    1. Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
    2. Laboratories that belong to the UGent Aquaculture R&D Consortium, Ghent University, Gent, Belgium.
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  • P. Bossier

    1. Laboratory of Aquaculture & Artemia Reference Center and
    2. Laboratories that belong to the UGent Aquaculture R&D Consortium, Ghent University, Gent, Belgium.
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*E-mail kristof.dierckens@UGent.be; Tel. (+32) 9264 37 54; Fax (+32) 9264 41 93.

Summary

The use of probiotic microorganisms in aquaculture is gaining a lot of interest. Gnotobiotic model systems are required in order to fully understand the effects and modes-of-action of these microorganisms, as the native microbial communities present in non-sterile animals can lead to false conclusions. In this study, a gnotobiotic sea bass larvae (Dicentrarchus labrax) test system was developed. In order to obtain bacteria-free animals, the eggs were disinfected with glutaraldehyde and subsequently incubated in a solution of rifampicin and ampicillin. Axenity was confirmed using culture-dependent and -independent techniques. The gnotobiotic larvae were fed axenic Artemia sp. from 7 days after hatching onwards. In the challenge test, one of the three opportunistic pathogens, Aeromonas hydrophila, Listonella anguillarum serovar O1 and O2a, was added to the model system via the water and encapsulated in Artemia sp. Only serovar O2a led to increased mortality in the sea bass larvae. The presented gnotobiotic model can be used for research on, among others, reciprocal metabolic effects between microorganisms and the host (e.g. as measured by gene expression), immunostimulants, pharmacological research and the histological development of the gastrointestinal tract and growth of larvae.

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