Fluorescence-Driven Detection of Heavy Metals Using a PdnaK-Regulated E. coli Biosensor
Yun Seul Ha
Gyeonggi Suwon International School, Gyeonggi-do, South Korea
Publication date: November 20, 2025
Gyeonggi Suwon International School, Gyeonggi-do, South Korea
Publication date: November 20, 2025
DOI: http://doi.org/10.34614/JIYRC2025II22
ABSTRACT
Heavy metal pollution poses significant environmental and health risks due to its persistence, bioaccumulation, and toxicity at low concentrations. In this study, we developed a whole-cell Escherichia coli biosensor regulated by the heat shock promoter PdnaK, which drives green fluorescent protein (GFP) expression in response to protein misfolding and oxidative stress induced by heavy metals. The PdnaK-GFP-pZA plasmid was constructed and transformed into E. coli, and biosensor performance was evaluated against cadmium chloride, lead(II) acetate, and zinc chloride. Bacterial growth (OD600) and GFP fluorescence were measured across a range of metal concentrations (1–2000 µM). Results revealed metal-specific activation patterns and optimal detection ranges: cadmium chloride (3–1000 µM), lead(II) acetate (1–10 µM), and zinc chloride (3–10 µM). Notably, lead(II) acetate triggered the strongest fluorescence response at just 1 µM, indicating the highest sensitivity among the tested metals. At very high concentrations, fluorescence decreased due to cytotoxicity. These findings demonstrate the PdnaK-GFP system’s potential as a cost-effective, selective, and quantitative tool for environmental heavy metal detection.
Heavy metal pollution poses significant environmental and health risks due to its persistence, bioaccumulation, and toxicity at low concentrations. In this study, we developed a whole-cell Escherichia coli biosensor regulated by the heat shock promoter PdnaK, which drives green fluorescent protein (GFP) expression in response to protein misfolding and oxidative stress induced by heavy metals. The PdnaK-GFP-pZA plasmid was constructed and transformed into E. coli, and biosensor performance was evaluated against cadmium chloride, lead(II) acetate, and zinc chloride. Bacterial growth (OD600) and GFP fluorescence were measured across a range of metal concentrations (1–2000 µM). Results revealed metal-specific activation patterns and optimal detection ranges: cadmium chloride (3–1000 µM), lead(II) acetate (1–10 µM), and zinc chloride (3–10 µM). Notably, lead(II) acetate triggered the strongest fluorescence response at just 1 µM, indicating the highest sensitivity among the tested metals. At very high concentrations, fluorescence decreased due to cytotoxicity. These findings demonstrate the PdnaK-GFP system’s potential as a cost-effective, selective, and quantitative tool for environmental heavy metal detection.
