Fig. 2. Phenotypic drug resistance is heritable and semi-stable.

(A) Small and large colonies were picked, resuspended in liquid media, and plated immediately (t = 0) and then passaged through liquid media without drug and plated at indicated time points. Ratio of colonies on INH plates/plates without INH was measured. SP, starting population. Significance was determined by unpaired t test. (B) LCVs and SCVs were picked from INH plates, resuspended in 7H9 media, and replated onto plates without drug. The histograms of the resulting colony sizes from each colony type after immediate replating are shown. (C) Large and small colonies were picked from INH plates, and cells were loaded into a microfluidic device and imaged for ~48 hours in media with INH (4 μg/ml). (D) Quantification of cell size at birth. Significance was determined by unpaired t test. (E) Quantification of time from birth to division for individual cells. Significance was determined by unpaired Student’s t test. For all panels, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.