SRX2060218 MD2_S13_L001_R2_001 SRP083122 PRJNA340230 Whole DNA isolation_V3 region specific primer amplification_Next generation Illumina Miseq SRS1651835 SAMN05554689 MD2_S13_L001_R2_001 AMPLICON METAGENOMIC PCR Illumina MiSeq