Fig. 4

Analysis of three negative control sample types reveals contaminating taxa. Data for negative controls was acquired using 16S V1-V2 rRNA marker gene sequencing analyzed on the Illumina MiSeq platform. Data from 11 experiments were pooled. a Comparison of average read counts. Experimental samples had an average read count of 137,243 and negative control samples had an average read count of 6613. b Heat map summary of bacterial lineages present in negative control samples. Different OTUs are present in DNA-extraction controls (“blank extraction” and “blank swab”) and library preparation controls (“library blank”) collected over multiple sequencing runs