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12Vibrio tasmaniensis V. splendidus and V. neptunius species were worldwide distributed and associated 13 with aquaculture and been reported as the cause of diseases in aquatic organisms. Polyphasic analyses for 14 bacterial identification are not feasible for routine diagnostic because of the time involved. The aim of 15 this study is to design three PCR primer sets that can assist with a fast detection of these species. They 16 were designed from the 16S ribosomal RNA gene, and PCR conditions were found. Each PCR test 17 successfully identified all the tested strains of each target species. The combined specificity of V.

Preventing vibriosis in juvenile cultured Turbot Scophthalmus maximus caused by Vibrio anguillarum frequently requires the use of feed supplemented with antibiotics in addition to vaccines. Whether the use of probiotics instead of antibiotics in juvenile Turbot is a safer strategy requires more study. The antibacterial potential of 148 Vibrio spp. strains (mostly isolated from cultures of healthy oysters, clams, and Turbot) was analyzed in vitro against V. anguillarum and other pathogens by means of an agar diffusion assay. A wide spectrum of inhibitory activity was shown by 9 strains. Based on their easy phenotypic differentiation from V. anguillarum, we selected two strains (S1 and S2, both isolated from the European flat oyster Ostrea edulis) for testing in juvenile Turbot (3 g). None of the strains were virulent by intraperitoneal or bath challenges, and all were susceptible to the antibiotics most frequently used in aquaculture. Three different stocks of Turbot, which were assayed separately, were significantly protected from infection with V. anguillarum. The final survival rates of fish treated in mixed challenges with S1 or S2 and V. anguillarum were 44% and 66%, respectively, whereas only 17% of the fish treated with only the pathogenic strain survived. The application of probiotic strains also increased the survival time of juvenile Turbot after infection with V. anguillarum. Both strains persisted in the epidermal mucus layer of the fish for 30 d, and they were not displaced by the pathogen. These data prove the efficacy of using bacteria well adapted to the dynamics of culture production as a way to provide juvenile Turbot immediate protection against infection by V. anguillarum. Moreover, the epidermal mucus sampling was useful for investigating the persistence of both probiotic strains when exposed to the pathogen.