16s rDNA of gut microbiota
The V3-V4 region of the bacterias 16S ribosomal RNA (rRNA) gene was amplifified with barcode-indexed primers (338F and 806R) by thermocycler Polymerase Chain Reaction (PCR system (GeneAmp 9700, ABI, Hampton, NH, USA) using FastPfu Polymerase. Amplicons were purifified using AxyPrep DNA GelExtraction Kit (Axygen Biosciences, Union City, CA, USA), then quantifified using QuantiFluor-ST (Promega, Madison, WI, USA). Sequencing was performed using the Illumina MiSeq platform (Illumina, San Diego, CA, USA).