fecal sample
bacterial DNA was extracted by the cetyltrimethylammonium bromide method. The variable V3V4 regions were designated as the target regions for sequencing. The primer 341F (5-CCTACGGGNGGCWGCAG-3') and 805R (5-GACTACHVGGGTATCTAATCC-3) were used for PCR amplification process. Subsequently, the PCR products underwent purification by utilizing AMPure XT beads and were quantified employing the Qubit assay kit. The qualified libraries were evaluated by the Agilent 2100 Bioanalyzerand the Library Quantification Kit for Illumina, and then sequenced by NovaSeq PE250 platform.