Fig. 6

The fewer the number of bacterial reads in a metagenome, the higher the proportion the target bacteria must constitute in order to accurately detect ARGs. The ratio of isolate reads required for ARG detection in a metagenome (log10 y-axis), grouped by isolates’ genome size, was plotted as a function of total reads in metagenome (x-axis, M = million). Estimates were conducted for a “best case scenario”, where all reads in the metagenome mapped to bacteria. Isolate genome sizes of 3, 4, and 5 Mbp (million base pairs) are differentiated by point shape and colour. For each genome size (colour), isolate genome coverage levels are differentiated by linetype: 5X coverage, dotted; 10X coverage, solid