Soil bacteria
The DNA from soil bacteria and fungi was extracted following the cetyltrimethylammonium bromide (CTAB) method, and the quality and concentration of DNA were then detected by agarose gel electrophoresis. The primers 515F and 806R were used to amplify the V4 region of the 16S rRNA gene (Peiffer et al., 2013). The ITS1 regions of the fungi were amplified by PCR using the primers ITS511737 and ITS22043R (Lu et al., 2013). PCR was performed as described below: 1 min of denaturation at 98 C, 30 cycles at 98 C for 10 s, 50 C for 30 s, 72 C for 30 s, and a final extension at 72 C for 5 min. The products obtained after amplification were detected by 2% agarose gel electrophoresis and purified using a GeneJET Gel Extraction Kit (Thermo Scientific, Carlsbad, CA, USA). Following purification, sequencing libraries were generated using an NEB Next Ultra DNA Library Prep Kit for Illumina (NEB, USA) following the manufacturers recommendations, and index codes were added. The library was sequenced on an Illumina HiSeq platform at Novogene Biotechnology Co., Ltd. Beijing, China