Bacterial-based electrochemical and optical sensing systems that respond in a highly selective and sensitive manner to antimonite and arsenite have been developed. This was accomplished by using genetically engineered bacteria bearing one of two plasmids constructed for our studies. The first plasmid, pBGD23, contains the operator/promoter region (O/P) and the gene of the ArsR protein from the ars operon upstream from the β-galactosidase gene. In the absence of antimonite/arsenite, ArsR binds to the 0/P site and prevents the transcription of the genes for ArsR and β-galactosidase, thus blocking expression of these proteins. When antimonite or arsenite is present in the sample, it binds to the ArsR protein, causing a conformational change in ArsR that leads to its release from the O/P site of the plasmid, thus allowing for the expression of β-galactosidase. Then, the amount of β-galactosidase expressed is quantified by using a substrate that produces a product that can be monitored electrochemically. In the second plasmid, pRLUX, the gene for ArsR is upstream from the reporter gene, luxAB, that encodes for the enzyme luciferase, whose activity can be monitored by bioluminescence. These bacterial sensing systems have excellent detection limits, respond selectively to arsenite and antimonite, and show no significant response to phosphate, sulfate, nitrate, and carbonate.
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The work on which this report is based was supported in part by the United States Department of the Interior, Washington, D.C. as authorized by the Water Resources Research Act of P.L. 101-397.
Daunert, Sylvia; Scott, Donna; and Ramanathan, Sridhar, "Metal-Resistance Genetically Engineered Bacteria" (1996). KWRRI Research Reports. 10.