The highly variable microbiota associated to intestinal mucosa correlates with growth and hypoxia resistance of sea bass, Dicentrarchus labrax, submitted to different nutritional histories

François-Joël Gatesoupe (1, 2, 3) , Christine Huelvan (3, 2) , Nicolas Le Bayon (3, 2) , Hervé Le Delliou (3, 2) , Lauriane Madec (3, 2) , Olivier Mouchel (3, 2) , Patrick Quazuguel (3, 2) , David Mazurais (3, 2) , Jose-Luis Zambonino-Infante (3, 2)

1 NuMéA - Nutrition, Métabolisme, Aquaculture
2 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer
3 LEMAR - Laboratoire des Sciences de l'Environnement Marin (LEMAR)

Background: The better understanding of how intestinal microbiota interacts with fish health is one of the key to sustainable aquaculture development. The present experiment aimed at correlating active microbiota associated to intestinal mucosa with Specific Growth Rate (SGR) and Hypoxia Resistance Time (HRT) in European sea bass individuals submitted to different nutritional histories: the fish were fed either standard or unbalanced diets at first feeding, and then mixed before repeating the dietary challenge in a common garden approach at the juvenile stage. Results: A diet deficient in essential fatty acids (LH) lowered both SGR and HRT in sea bass, especially when the deficiency was already applied at first feeding. A protein-deficient diet with high starch supply (HG) reduced SGR to a lesser extent than LH, but it did not affect HRT. In overall average, 94 % of pyrosequencing reads corresponded to Proteobacteria, and the differences in Operational Taxonomy Units (OTUs) composition were mildly significant between experimental groups, mainly due to high individual variability. The highest and the lowest Bray-Curtis indices of intra-group similarity were observed in the two groups fed standard starter diet, and then mixed before the final dietary challenge with fish already exposed to the nutritional deficiency at first feeding (0.60 and 0.42 with diets HG and LH, respectively). Most noticeably, the median percentage of Escherichia-Shigella OTU\₁ was less in the group LH with standard starter diet. Disregarding the nutritional history of each individual, strong correlation appeared between (1) OTU richness and SGR, and (2) dominance index and HRT. The two physiological traits correlated also with the relative abundance of distinct OTUs (positive correlations: Pseudomonas sp. OTU\₃ and Herbaspirillum sp. OTU\₁0 with SGR, Paracoccus sp. OTU\₄ and Vibrio sp. OTU\₇ with HRT; negative correlation: Rhizobium sp. OTU\₉ with HRT). Conclusions: In sea bass, gut microbiota characteristics and physiological traits of individuals are linked together, interfering with nutritional history, and resulting in high variability among individual microbiota. Many samples and tank replicates seem necessary to further investigate the effect of experimental treatments on gut microbiota composition, and to test the hypothesis whether microbiotypes may be delineated in fish.

Mots clés: Host-microbe interaction; gut microbiota; glucose-metabolism; ACL; Physiological status; lactic-acid bacteria; vibrio-cholerae; fish-oil; Pyrosequencing; Alternative feed ingredients; atlantic salmon; Autochthonous bacteria; epithelial mucosa; rainbow-trout; salvelinus-alpinus l.; 16S rRNA; vegetable-oils

Domaines: Médecine vétérinaire et santé animale; Microbiologie et Parasitologie; Alimentation et Nutrition; Biodiversité et Ecologie

François-Joël Gatesoupe, Christine Huelvan, Nicolas Le Bayon, Hervé Le Delliou, Lauriane Madec, et al.. The highly variable microbiota associated to intestinal mucosa correlates with growth and hypoxia resistance of sea bass, Dicentrarchus labrax, submitted to different nutritional histories. BMC Microbiology, 2016, 16, pp.266. ⟨10.1186/s12866-016-0885-2⟩. ⟨hal-01483197⟩