We used nine genetically distinct Mtb strains, with three strains from each of the following Mtb lineages: Lineage 1 (L1; also known as the East-Africa and India Lineage), Lineage 2 (L2; the East Asian Lineage), and Lineage 4 (L4; the Euro-American Lineage) (Comas et al. 2010 (link); Gagneux 2018 (link)). All strains were previously isolated from patients, fully drug-susceptible, and previously characterized by Borrell et al. (2019) (link) (supplementary table S1 , Supplementary Material online).
Prior to all experimentation, starter cultures for each Mtb strain were prepared by recovering a 20 μl aliquot from frozen stocks into a 10 ml volume of Middlebrook 7H9 broth (BD), supplemented with an albumin (Fraction V, Roche), dextrose (Sigma–Aldrich), catalase (Sigma–Aldrich), and 0.05% Tween 80 (AppliChem) (hereafter designated as 7H9 ADC). These starter cultures were incubated until their optical density at wavelength of 600 nm (OD600) was ∼0.50, and were then used for in vitro assays.
Prior to all experimentation, starter cultures for each Mtb strain were prepared by recovering a 20 μl aliquot from frozen stocks into a 10 ml volume of Middlebrook 7H9 broth (BD), supplemented with an albumin (Fraction V, Roche), dextrose (Sigma–Aldrich), catalase (Sigma–Aldrich), and 0.05% Tween 80 (AppliChem) (hereafter designated as 7H9 ADC). These starter cultures were incubated until their optical density at wavelength of 600 nm (OD600) was ∼0.50, and were then used for in vitro assays.