16S rRNA genes of microbial consortia
The V3-V4 region of the 16S rRNA gene was amplified and prepared for sequencing using two steps PCR procedure involving the primers 341F (5'-CCTACGGGRBGCASCAG-3') and 806R (5'-GGACTACNNGGGTATCTAAT-3') in the first step, and then the same primers with additional adapters and barecodes in the second step. PCR products were purified with Agencourt AMPure XP Beads (Beckman Coulter Genomics, MA, USA), quantified using Quant-iT High-Sensitivity DNA Assay Kit (Life Technologies), and pooled in equi-molar concentrations. The pooled library was adjusted to 4 nM concentration before denaturation and dilution to a final 20 pM library following standard Illumina protocol, and paired-end sequenced (2x250 bp) on an Illumina MiSeq using MiSeq reagent kit v2.