Fig. 3: Accurate quantification of barcode relative abundance.

a Schematic of the CompAReSeq barcode sequencing method. Each strain includes a unique 7 bp barcode on the pZE24 plasmid. Strains harboring tetracycline resistance genes, plus an empty plasmid control, were mixed at equal relative abundances. These were then inoculated into media containing antibiotics at different concentrations. Following growth for 20–48 h, plasmid DNA was extracted and prepared for sequencing using two PCR steps that added sample-specific barcodes and UMIs, then added sequencing adapters and amplified DNA. The output amplicons were then sequenced, and the number of UMIs identified per barcode was counted. b Relationship between input barcode abundance and measured barcode abundance by sequencing. Each point represents a barcode count, from one of three replicate pools. The blue line indicates the linear trend line and the gray line indicates a slope = 1 (i.e., perfect measurement of input abundance).