DNA-seq of soil bacteria
The soil DNA was extracted using a PowerSoil DNA Isolation Kit (MO BIO Laboratories, USA). The V4 region of 16s rDNA was amplified using primer pairs 515F/806R (Caporaso et al., 2012). Primer 515F contained a 12 bp barcode unique to each sample for Miseq sequencing detection. All PCR reactions were carried out in triplicate in a 25 l system, as described by Caporaso et al. (Caporaso et al., 2011). The PCR products were then pooled, purified, and sequenced on an Illumina NoraSeq platform at Majorbio Biotech Co., Ltd. (Shanghai, China).