A Portable, Encapsulated Microbial Whole-Cell Biosensing System for the Detection of Bioavailable Copper (II) in Soil

Area of Science:

• Environmental Science
• Biotechnology
• Analytical Chemistry

Background:

• Conventional methods for measuring micronutrients like copper (II) are often laboratory-based and complex.
• There is a need for field-deployable tools to monitor bioavailable micronutrient concentrations directly in environmental matrices.
• Existing techniques are not suitable for rapid, on-site assessment of essential trace elements.

Purpose of the Study:

• To develop a portable, field-deployable whole-cell biosensor for monitoring bioavailable copper (II) in soil.
• To engineer a microbial biosensing system with a Cu2+-responsive protein for signal generation.
• To optimize and validate the biosensor's performance in complex soil matrices.

Main Methods:

• Engineered a microbial whole-cell biosensing (MWCB) system using a circularly permuted green fluorescent protein (GFP) with an inserted Cu2+-binding motif.
• Designed and constructed plasmids encoding the sensing-reporting protein for Cu2+ detection.
• Encapsulated the optimized biosensor in polyacrylate-alginate beads for soil deployment and used a portable imaging device for fluorescence detection.

Main Results:

• The developed biosensor demonstrated selectivity, sensitivity, and reproducibility in both liquid and soil samples.
• The optimized encapsulated biosensor achieved a limit of detection (LoD) of 0.27 mg/L in solution and 1.26 mg/kg in soil for Cu2+.
• Validated the portable imaging tool for field-based biosensing applications.

Conclusions:

• A portable, field-deployable whole-cell biosensor for bioavailable copper (II) was successfully developed and optimized.
• The biosensor requires minimal sample preparation and can withstand complex soil matrices.
• This technology offers a promising solution for on-site monitoring of essential micronutrients in environmental samples.