16S rRNA gene amplicon sequencing of control: PCR negative control
DNA was extracted with MoBio DNA Isolation kit; PCRs were performed following the Illumina protocol for 16S Metagenomic Sequencing Library Preparation (part # 15044223 Rev. B) using 341F and 805R primers (Klindworth et al., 2013) with Illumina overhang adapters; PCR products were purified with magnetic beads; A second PCR step was performed to attach dual indices and Illumina sequencing adapters; PCR products were purified with magnetic beads; Sample library DNA was quantified using a Qubit and libraries were pooled in equimolar quantities.