Pasteurized milk B
Amplification of the 16S V6-V8 region (16S rDNA) was performed  using a two-step dual-indexed PCR approach specifically designed for Illumina  instruments. In a first step, the gene specific sequence is fused to the  Illumina TruSeq sequencing primers and PCR was carried out. The second PCR  step, performed with 50- to 100-fold dilution of the previously purified PCR  product as a DNA template, allowed the addition of barcodes (dual-indexed)  and the missing sequence required for Illumina sequencing. Barcoded amplicons  were then pooled in equimolar concentration for sequencing on the Illumina  Miseq.