Fig. 5
a Linear expression ranges of luciferase in the presence of lead with regression coefficient R2 = 0.960. The maximum expression of the luciferase gene was 12 h. Luciferase expression (in the range of 10–100) is linear with high regression, and the sensor in this range can detect the presence of lead with a lower error coefficient. b Difference in the growth rate of pGL3-luc/pbr biosensor compared to E. coli strain DH5α. Resistance may be related to the pbrR regulatory gene. The presence of pbrR as regulator gene, in the positions of the binding of the lead ion, makes the promoter somewhat resistant to lead toxicity and more resistant to plasmid-free bacteria