Metabolic engineering-enabled dual-color biosensor for discriminative and sensitive detection of toxic lead and mercury in environmental waters

Abstract

The ubiquity of toxic heavy metals, particularly lead (Pb) and mercury (Hg), in environmental waters severely threatens ecosystems and human health. We developed a metabolic engineering-based dual-color bacterial biosensor for the sensitive and discriminative detection of Pb(II) and Hg(II) at nanomolar levels. The biosensor leverages the synthetic biology approach to integrate two pigments, prodeoxyviolacein (PDV) and deoxyviolacein (DV), into a single construct that responds distinctly to Pb(II) and Hg(II), respectively. The engineered E. coli biosensor exhibits a detection range of 0.732–3000 nM for Pb(II) and 0.183–750 nM for Hg(II), with low detection limits of 0.732 nM for Pb(II) and 0.183 nM for Hg(II). The biosensor demonstrated high sensitivity, selectivity, and accuracy with a recovery rate close to 1 in freshwater and seawater matrices. Notably, the biosensor's visual readout allows for rapid, equipment-free assessment. It is a practical tool for real-world monitoring of heavy metal pollution, especially in remote or resource-limited settings. This study underscores the potential of whole-cell biosensors as a sustainable and effective alternative to traditional heavy metal detection methods.