title: 16S RNA V3-V4 grassland soil
design: The V3  V4 region of the 16S rRNA gene was amplified by PCR with the following primers: forward 5'CCTACGGGNGGCWGCAG and reverse 5'GACTACHVGGGTATCTAATCC selected from Klindworth et al. (2013) following the manufactured instruction for to obtain the library