title: consortium PB2 at stage 2 of enrichment
design: 16S rRNA gene was amplified using 341F and 805R primers, targeting V3-V4 variable regions and 2X sparQ HiFi PCR master Mix (QuantaBio, USA). The amplification condition included an initial denaturation step 2 min at 98 C, followed by 30 cycles of 98 C for 20 s, 60 C for 30 s, and 72 C for 60 s, followed by a single step final extension step at 72 C for 1 min. Subsequently, 16S amplicon, expected size 550 bp, were purified using sparQ Puremag Beads (QuantaBio, USA) and indexed using 2.5 l of each Nextera XT index primer in a 50 l PCR reaction, followed by 8-10 cycles of PCR condition above. The final PCR products were cleaned, pooled, and diluted to final loading concentration at 4 pM.