Fish protein hydrolysate is rich in free amino acids, bioactive compounds and water-soluble proteins that improve feed digestibility and palatability, thus promoting fish growth and feed utilization.
More...Fish protein hydrolysate is rich in free amino acids, bioactive compounds and water-soluble proteins that improve feed digestibility and palatability, thus promoting fish growth and feed utilization. Protein hydrolysate from yeast (Saccharomyces cerevisiae) is assumed to have similar beneficial effects of fish protein hydrolysate but, in addition, it contains several functional compounds, such as the nucleotides and the carbohydrates present in its cell wall (mannan-oligosaccharides and β-glucans), which have positive influence on fish health. The present study aimed to investigate the effects of a diet rich in plant proteins, supplemented with 5% of either fish protein hydrolysate or autolysed dry yeast (HiCell®, Biorigin) on intestinal microbiota of gilthead sea bream. For this purpose, 720 juvenile sea bream of were fed for 13 weeks with the three aforementioned diets in triplicate. For metagenomic analysis, bacterial DNA was extracted from 250 mg of intestinal content of 15 fish per diet. The hypervariable V3 and V4 regions of the 16S rRNA gene were amplified by PCR using forward primer Pro341F (5’ CCTACGGGNGGCWGCAG 3’) and reverse primer Pro805R (5’ GACTACHVGGTATCTAATCC 3’). The 16S ribosomal RNA gene amplicon libraries were prepared following the Illumina and sequenced on an Illumina MiSeq platform (Illumina) with paired-end 2×300 bp sequencing chemistry. The raw FASTQ sequencing data were processed QIIME v1.9.1 and Greengenes database (http://greengenes.lbl.gov) for Operational Taxonomic Units (OTU) identification. Our data revealed that inclusion of autolysed dry yeast was associated with an increased bacterial diversity compared to fish protein hydrolysed supplemented diet. In particular, fish receiving autolysed yeast showed higher abundance of Bacillus and Shewanella genera, besides to be characterized by specific bacterial genera, such as Megasphera, potentially beneficial for host.
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