Fig. 1From: Exploring protocol bias in airway microbiome studies: one versus two PCR steps and 16S rRNA gene region V3 V4 versus V4Comparison of the number of sequences and amplicon sequence variants (ASVs), retained at each bioinformatic filtering step for procedural samples (PSB, PBAL, OW, NCS) collected from 23 participants (n = 92 samples). Setup 1 (2-step PCR; V3 V4 region), Setup 2 (2-step PCR; V4 region), Setup 3 (1-step PCR; V4 region)Back to article page