design: Total genomic DNA was extracted from 0.2 g of fecal samples. After quality assessment, the DNA was fragmented to about 350 bp using Covaris M220 and paired - end libraries were prepared with NEXTFLEX kit. Metagenomic sequencing was carried out on Illumina NovaSeq X Plus, targeting 20 million high - quality 166 - bp paired - end reads per sample. Sequencing data were processed by fastp, MEGAHIT, etc., including filtering, assembly, ORF prediction, and finally taxonomic and functional annotation.