Fig. 4

a Luciferase expression in different concentrations of lead. The expression of luciferase was decreased with a slight gradient from 100 to 200 micro molar. Luciferase gene expression was shown to be present in different concentrations of lead. Luciferase expression is increased by increasing lead, but from a concentration level of 100 μM onwards, the expression rate decreases due to the toxic effects of lead, and this decrease intensifies from a concentration level of 200 μM onwards. Relative luminescence units (RLU). b The expression of pGL3-luc/pbr biosensor reporter gene at different times. The biosensor was treated in the presence of lead in three time periods of 8, 12, and 16 h, and the expression gene of the reporting gene was evaluated to obtain the appropriate time for the treatment of the biosensor with lead. The expression time is low at 8 h, and the expression time is reduced at 16 h due to the overload of the biosensor bacteria and the toxic effects of lead metal