Fig. 2.

Growth curves of the chassis cells with the selection plasmid in response to lead and ampicillin. The optical density at 600 nm of the E. coli (pZE21-PBS) strain was measured with lead at different concentrations of 0 µM (squares), 1 µM (circles), 5 µM (up triangles), 10 µM (down triangles), 20 µM (diamonds), and 50 µM (left triangles). Ampicillin was used at a 100 µg mL⁻¹ and b 200 µg mL⁻¹. Experiments were performed in triplicate, and data represent the averages and standard deviations of the means