Construction of a sensitive and specific lead biosensor using a genetically engineered bacterial system with a luciferase gene reporter controlled by pbr and cadA promoters.

BACKGROUND A bacterial biosensor refers to genetically engineered bacteria that produce an assessable signal in the presence of a physical or chemical agent in the environment. METHODS We have designed and evaluated a bacterial biosensor expressing a luciferase reporter gene controlled by pbr and cadA promoters in Cupriavidus metallidurans (previously termed Ralstonia metallidurans) containing the CH34 and pI258 plasmids of Staphylococcus aureus, respectively, and that can be used for the detection of heavy metals. In the present study, we have produced and evaluated biosensor plasmids designated pGL3-luc/pbr biosensor and pGL3-luc/cad biosensor, that were based on the expression of luc+ and under the control of the cad promoter and the cadC gene of S. aureus plasmid pI258 and pbr promoter and pbrR gene from plasmid pMOL30 of Cupriavidus metallidurans. RESULTS We found that the pGL3-luc/pbr biosensor may be used to measure lead concentrations between 1-100 μM in the presence of other metals, including zinc, cadmium, tin and nickel. The latter metals did not result in any significant signal. The pGL3-luc/cad biosensor could detect lead concentrations between 10 nM to 10 μM. CONCLUSIONS This biosensor was found to be specific for measuring lead ions in both environmental and biological samples.