Effect of the addition of Lactobacillus delbrueckii subsp. delbrueckii on the gut microbiota composition and contribution to the well-being of European sea bass (Dicentrarchus labrax, L.)

The present study aimed to test the effects of probiotic treatment on gut microbiota and the contribution to the well-being of European sea bass (Dicentrarchus labrax, L.). A bacterial strain of Lactobacillus delbrueckii subsp. delbrueckii (AS13B), isolated from adult European sea bass gut, was administered during sea bass development using Brachionus plicatilis and/or Artemia salina as carriers. The effective strain colonization and modulation of the gut microbiota, the mortality and the cortisol levels of sea bass were monitored during early developmental stages. The L. delbrueckii subsp. delbrueckii strain showed good capability to colonize the gut of sea bass larvae, therefore modifying the gut microbiota, and exerting positive effects on the survival of the treated sea bass. L. delbrueckii subsp. delbrueckii as a probiotic dietary supplement represents an advantageous and ecological strategy for improving the health of fish in aquaculture and increasing fish production.Key words: Lactobacillus delbrueckii subsp. delbrueckii, probiotic strain, Dicentrarchus labrax, aquaculture, gut microbiota, mortality, stres