Biodetection and bioremediation of copper ions in environmental water samples using a temperature-controlled, dual-functional Escherichia coli cell.

Although a variety of whole-cell biosensors and biosorbents have been developed for detection and removal of heavy metal contaminants, few whole cells can be applied to both monitoring and remediation of copper pollution in water. In this study, a modified plasmid was constructed by incorporating a copper-sensing element and a copper-adsorbing element into a temperature-inducible plasmid, pBV220. This plasmid was subsequently transformed into an engineered Escherichia coli strain lacking copA and cueO. This dual-functional E. coli cell selectively responded to copper ions with a linear detection range of 0.01-25 µM at 37 °C and could express surface-displayed CueR when treated at 42 °C without any costly chemical inducers. The display of CueR on the cell surface specifically enhanced its copper adsorption capacity and rapidly removed copper ions from aqueous solutions. In addition, the CueR surface-displayed cells could be regenerated by adsorption-desorption cycles via pH regulation. Moreover, by simply using two different temperatures, the detection or adsorption of copper using this dual-functional whole cell was achieved without any cross-interference. Most importantly, it provided highly sensitive, accurate quantification, and effective removal of copper in real environmental water samples. Thus, this E. coli cell can be used for large-scale detection and remediation of copper pollutants.