Colonies inside the inhibition zone after the second step of the TDtest. (A) low-tolerance WT strain. (B) medium-tolerance vapB mutant strain (tbl3a). (C) high-tolerance metG mutant strain (tbl5a). (D) low-persistence WT strain (MGY). (E) hipA7 high-persistence mutant (MGHY, Table 1)13,14. For more controls, See Supplementary Figs S1, S5 and S6. Disk diameter: 6 mm.