Host-Associated Bacterial Succession during the Early Embryonic Stages and First Feeding in Farmed Gilthead Sea Bream ().

One of the most widely reared fish in the Mediterranean Sea is . The succession of whole-body microbiota in fertilized eggs, five, 15, 21 and 71 days post hatch (dph) larvae and the contribution of the rearing water and the provided feed (rotifers, sp. and commercial diet) to the host's microbiota was investigated by 454 pyrosequencing of the 16S rRNA gene diversity. In total, 1917 bacterial operational taxonomic units (OTUs) were found in all samples. On average, between 93 ± 2.1 and 366 ± 9.2 bacterial OTUs per sample were found, with most of them belonging to Proteobacteria and Bacteroidetes. Ten OTUs were shared between all stages and were also detected in the rearing water or diet. The highest OTU richness occurred at the egg stage and the lowest at the yolk sac stage (5 dph). The rearing water and diet microbial communities contributed in microbiota without overlaps in their microbial composition and structure. The commercial diet showed higher contribution to the microbiota than the rearing water. After stage D71 the observed microbiota showed similarities with that of adult as indicated by the increased number of OTUs associated with γ-Proteobacteria and Firmicutes.