Taurine-enriched diet
DNA was isolated from the intestine samples obtained from  turbot receiving a control and a taurine-enriched diet for 1 month.. For this, the DNeasy PowerSoil Pro Kit (Qiagen, Dsseldorf, Germany) was used following the manufacturer's protocol. Total DNA was assessed for its quality and quantity by 1.0% agarose gel electrophoresis, quantified with the ADNds Quant-iT PicoGreen kit (Invitrogen) using a Victor3 fluorometer (PerkinElmer) and purity was measured with a NanoDrop instrument (Thermo Fisher Scientific). All samples passing quality control were subjected to 16S rRNA V3-V4 amplicon library construction. Briefly, the V3-V4 region of the 16S rRNA gene (~460 bp) was amplified using universal prokaryotic-specific primers (16S amplicon PCR forward primer: 5-CCTACGGGNGGCWGCAG-3 and reverse primer: 5-GACTACHVGGGTATCTAATCC-3) as described by Klindworth et al. (2013). After purification of the amplicons with AMPure XP beads, a 16S rRNA gene metabarcoding library was prepared using the Nextera XT Index Kit (Illumina). Paired-end sequencing (2  300 bp) was subsequently performed on an Illumina MiSeq platform by Macrogen Inc. (Seoul, Republic of Korea).