title: 16S amplicon of microorganism community : negative control
design: negative PCR  control, first amplification of a region of the rRNA 16S gene with 515F-Y/926R primer pair  (5-GTGYCAGCMGCCGCGGTAA-3/5-CCGYCAATTYMTTTRAGTTT-3),second amplification to add Illumina adaptors, sequencing 2*250 PE, Illumina MiSeq Reagent Kit v232