sequences of gene
Metagenomic sequencing and analysis of the fecal samples were conducted using an Illumina HiSeq 2500 at Majorbio Bio-Pharm Technology Co., Ltd. The data were analyzed on the free online platform of Majorbio Cloud Platform (www.majorbio.com). Briefly, the raw sequencing reads were trimmed of adapters, and low-quality reads (length<50 bp or with average quality value < 20) were removed by fastp (v0.20.0). The quality-filtered data were assembled using MEGAHIT (v1.1.2). Contigs with a length  300 bp were selected as the final assembling result. Open reading frames (ORFs) from each assembled contigs were predicted using Prodigal (v2.6.3) and a length  100 bp ORFs were retrieved. A non-redundant gene catalog was constructed using CD-HIT (v4.7) with 90% sequence identity and 90% coverage. Gene abundance for a certain sample was estimated by SOAPaligner (v2.21) with 95% identity.