DNA extraction was performed using the QIAamp DNA Stool Mini Kit (Qiagen Inc., Valencia, CA) according to the manufacturer's instructions.Third-generation sequencing technology was employed for full-length sequencing of the 16S rRNA gene. The primers 27F/1492R were used to amplify and sequence the full-length 16S rRNA gene.For single-molecule real-time sequencing (SMRT sequencing) on the PacBio RS II sequencing platform (Pacific Biosciences, Menlo Park, CA). The sequencing data were initially processed using the SMRT Portal software, which included the removal of adapter sequences and filtering of low-quality reads.