design: The E.Z.N.A Mag-Bind Soil DNA Kit was employed for the extraction of DNA. 16S rRNA amplicon sequencing was performed by Sangon Biotech (Shanghai) Co., Ltd. The Illumina MiSeq high-throughput sequencing system was used to target the V3V4 hypervariable region of the bacterial 16S rDNA gene. PCR amplification of the V3V4 regions was conducted using primers 341F (5-CCCTACACGACGCTCTTCCGATCTG (barcode) CCTACGGGNGGCWGCAG-3) and 805R (5-GACTGGAGTTCCTTGGCACCCGAGAATTCCAGACTACHVGGGTATCTAATCC-3).