Developing Inexpensive Methods for Detection of Toxic Metals in Oklahoma Water

Abstract

Cadmium is a naturally occurring metal found in the Earth’s crust; however, high concentrations may be toxic. This toxicity is especially concerning to Oklahomans due to excessive cadmium pollution in the Tri-State Area Lead-Zinc mining region. In order to develop inexpensive methodologies for the detection of cadmium, we purposed to generate a cadmium-sensitive bacteria using synthetic biology. We hypothesized that plasmids encoding a cadmium sensitive promoter could be used as biosensors for cadmium pollution. We generated a test construct encoding a cadmium sensitive promoter and a control construct encoding a constitutive promoter using recombinant DNA technology; both promoters controlled a pink chromoprotein as a reporter. Our construct was introduced into E. coli and exposed to various water samples to test responsiveness to cadmium contamination. Responsiveness was determined by evaluating the intensity of pink pigmentation that resulted from expression of the pink chromoprotein. A slight pink pigmentation was observed in both control and test constructs. The lack of responsiveness observed in our test construct could be due to the absence of cadmium in the water samples; however, pigmentation in the control was also fainter than expected. Further testing of both constructs in the presence and absence of purified cadmium is required.