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Millions of people worldwide are exposed to toxic levels of arsenic in drinking water. Bacteria have an efflux operon regulated by an arsenic sensitive inducible promoter. It is possible through recombinant DNA technology to isolate this promoter and combine it to a reporter system and transform bacteria to create a biosensor for arsenic. Induction of the arsenic-sensitive promoter occurs by the binding of arsenite to an inhibitory protein, de-repressing transcription. We have observed the arsenic responsive promoter from E. coli to have a consistent, low level of background induction. We have tested the hypothesis that by increasing the quantity of the inhibitory protein in the cell, we can quantifiably raise the threshold of the response. Our intention is to create a tunable biosensor to form the basis of a low-tech device that can reliably detect dangerous levels of arsenic in water for use in the developing world.  

Millions of people worldwide are exposed to toxic levels of arsenic in drinking water. Bacteria have an efflux operon regulated by an arsenic sensitive inducible promoter. It is possible through recombinant DNA technology to isolate this promoter and combine it to a reporter system and transform bacteria to create a biosensor for arsenic. Induction of the arsenic-sensitive promoter occurs by the binding of arsenite to an inhibitory protein, de-repressing transcription. We have observed the arsenic responsive promoter from E. coli to have a consistent, low level of background induction. We have tested the hypothesis that by increasing the quantity of the inhibitory protein in the cell, we can quantifiably raise the threshold of the response. Our intention is to create a tunable biosensor to form the basis of a low-tech device that can reliably detect dangerous levels of arsenic in water for use in the developing world.