The use of prebiotics in aquaculture aims at increasing the numbers of beneficial microbes in the gastrointestinal tract of fishes. However, the true effect of prebiotics exert on the fish microbiome is for the most part unknown. This study aimed at investigating the effects of the commercial prebiotic Previda® and the feed supplement saponin on Nile tilapia (Oreochromis niloticus L.). We used 454 pyrosequencing to characterize the gut microbiome of fish fed diets containing Previda®, saponin, a combination of both, and a control diet. After data normalization, 98,300 sequence reads were analyzed resulting in 331 unique operational taxonomic units (OTUs). Three phyla were present in all samples: Fusobacteria, Bacteroidetes, and Proteobacteria. Fusobacteria was the predominant phylum in all samples accounting for more than 80% of the OTUs. Within the Fusobacteria, the predominant genus was Cetobacterium with more than 76% of the sequences being ascribed to that species. Barnesiella was the second most common genus with more than 6% of the total sequences. Overall, there was not a significant difference in the composition of the gut microbiomes regardless of the diet. The overwhelming numbers of Cetobacterium sp. present in the gut of Nile tilapia could overshadow the effect of the treatments on other genera.
Candis Ray, Noemi Bujan, Andrea Tarnecki, Allen Davis D, Browdy C and Arias CR