Figure 3. Pellicle wet weights measured after 5 weeks of growth, for ancestral populations and populations after eight passages (n=2–3 per experimental strain, n=5 for H37Rv, see Figure 3—source data 1).

Pellicle wet weights increased for all experimental populations following passaging (Mann-Whitney U test, p-value=1.5e-06). The magnitude of this change varied, with two genetic backgrounds (MT55 & MT345) showing relatively dramatic increases in pellicle weight, approaching the phenotype of lab-adapted strain H37Rv. We also observed a trend towards increased variability in wet weights after passaging as a pellicle. Error bars represent range of wet weights across replicates.