Fig. 2

Tolerance of M. smegmatis cells expressing CtpB in presence of high doses of heavy-metal cations. Cultures in LB supplemented with increasing concentrations of cations: a Co²⁺, b Cd²⁺, c Cu²⁺, d Mn²⁺, e Ni²⁺, and f Zn²⁺ were incubated during 72 h at 37 °C and the OD₅₉₅ was measured. The absorbance measured for mycobacterial cells expressing CtpB (transformed with pALT10) and control cells (transformed with pMV261) is shown in gray and black lines, respectively. The data correspond to the mean OD₅₉₅ ± SEM from three independent experiments. Significant differences correspond to values of *P ≤ 0.05 and **** P ≤ 0.0001