title: Vibrio lentus protects gnotobiotic sea bass (Dicentrarchus labrax L.) larvae against challenge with Vibrio harveyi.
abstract: Due to the mounting awareness of the risks associated with the use of antibiotics in aquaculture, treatment with probiotics has recently emerged as the preferred environmental-friendly prophylactic approach in marine larviculture. However, the presence of unknown and variable microbiota in fish larvae makes it impossible to disentangle the efficacy of treatment with probiotics. In this respect, the recent development of a germ-free culture model for European sea bass (Dicentrarchus labrax L.) larvae opened the door for more controlled studies on the use of probiotics. In the present study, 206 bacterial isolates, retrieved from sea bass larvae and adults, were screened in vitro for haemolytic activity, bile tolerance and antagonistic activity against six sea bass pathogens. Subsequently, the harmlessness and the protective effect of the putative probiotic candidates against the sea bass pathogen Vibrio harveyi were evaluated in vivo adopting the previously developed germ-free sea bass larval model. An equivalence trial clearly showed that no harmful effect on larval survival was elicited by all three selected probiotic candidates: Bacillus sp. LT3, Vibrio lentus and Vibrio proteolyticus. Survival of Vibrio harveyi challenged larvae treated with V. lentus was superior in comparison with the untreated challenged group, whereas this was not the case for the larvae supplemented with Bacillus sp. LT3 and V. proteolyticus. In this respect, our results unmistakably revealed the protective effect of V. lentus against vibriosis caused by V. harveyi in gnotobiotic sea bass larvae, rendering this study the first in its kind.
authors.affiliation: Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. Electronic address: marlien.schaeck@ugent.be.
authors.forename: M
authors.initials: M
authors.lastname: Schaeck
authors.affiliation: Department of Comparative Physiology and Biometry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Duchateau
authors.affiliation: Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: W
authors.initials: W
authors.lastname: Van den Broeck
authors.affiliation: BCCM/LMG Bacteria Collection, Laboratory of Microbiology, Ghent University, Faculty of Sciences, Ledeganckstraat 35, 9000 Ghent, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Van Trappen
authors.affiliation: BCCM/LMG Bacteria Collection, Laboratory of Microbiology, Ghent University, Faculty of Sciences, Ledeganckstraat 35, 9000 Ghent, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: De Vos
authors.affiliation: Ecloserie Marine de Gravelines, Gravelines, France.
authors.forename: C
authors.initials: C
authors.lastname: Coulombet
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Boon
authors.affiliation: Department of Pathology, Bacteriology and Poultry diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Haesebrouck
authors.affiliation: Department of Pathology, Bacteriology and Poultry diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Decostere
mesh_terms: D000818:Animals; D000898:Antibiosis; D017756:Aquaculture; D001407:Bacillus / Q000502:physiology; D001492:Bass / Q000382:microbiology*; D005393:Fish Diseases / Q000382:microbiology* / Q000517:prevention & control*; D005856:Germ-Free Life; D019936:Probiotics; D014733:Vibrio / Q000502:physiology*; D014735:Vibrio Infections / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*
keywords: Aquaculture; Challenge; European sea bass; Gnotobiotic; Probiotics; Vibrio