C3.2 (CRX2036022; CRA030706)
After freeze-drying, 0.25g of samples were weighed quantitatively, and the total DNA of the samples was extracted using a DNA extraction kit (QIAGEN), and the concentration and purity of the DNA samples were detected using NanoDropOne (ThermoFisher). Specific primers 515F and 806R were used to amplify the V4 highly variable region of bacterial 16S rRNA, and sequencing libraries were constructed using Illumina Hiseq 4000 platform.