16S rRNA of  DH_1
DNA extraction, amplification, and sequencing were conducted by PersonalBio Biotechnology Co., Ltd. (Shanghai, China). In brief, complete DNA samples were extracted using the E.Z.N.ATM Mag-Bind Soil DNA Kit (M5635, OMEGA, USA), following the manufacturers protocol. The quantity and quality of the extracted DNA were assessed using a fluorescence spectrophotometer (Quantifluor-ST fluorometer, Promega, E6090; Quant-iT PicoGreen dsDNA Assay Kit, Invitrogen, P7589) at 260 nm and 280 nm, respectively, and was also detected via 1.2% agarose gel electrophoresis. PCR amplification of the bacterial 16S rRNA gene V3-V4 hypervariable region was performed using a forward primer (338F:5-ACTCCTACGGGAGGCAGCA-3) and reverse primer (806R:5-GGACTACHVGGGTWTCTAAT-3). The PCR reaction (25L) was prepared as follows: template DNA 1L, amplicon PCR forward primer (10M) 1L, amplicon PCR reverse primer (10M) 1L, dNTP (2.5 mM) 2L, Fast Pfu DNA Polymerase (0.25 L), 2 buffer (5L), and ddH2O (14.75L). PCR was performed using the following program: denaturation at 98 C for 5 min followed by 25 cycles consisting of denaturation at 98 C for 30 s, annealing at 52 C for 30 s, and extension at 72 C for 45 s, with a final extension of 5 min at 72 C. PE256 paired-end sequencing was performed according to the Illumina MiSeq (Illumina San Diego, CA, USA) instrument manual after the DNA libraries were mixed.