Researchers at Imperial College London and Zhejiang University have engineered E. coli bacteria into bioelectronic sensors capable of detecting chemicals such as mercury in water.

About the Bio-Sensors Developed Using E. coli

• A living biosensor made from genetically engineered Escherichia coli bacteria that converts mercury presence into an electrical signal readable by simple electronic devices.

How the Sensor Works

• Mechanism: These bacteria detect specific compounds, process the information, and generate electrical signals compatible with affordable electronic devices.
• E. coli engineered as a modular biosensor with three parts:
  • Sensing module – detects the target chemical.
  • Processing module – amplifies or processes the signal.
  • Output module – produces phenazines, molecules detectable via voltammetry (an electrochemical method).
• When phenazines contact an electrode, a measurable electrical current is generated.

Key Experiments

• Sugar Detection: Detected arabinose (a plant sugar) within 2 hours.
• Mercury Detection: Identified trace mercury ions in water (below WHO limits) within 3 hours.
• Logic Gate Demonstration: Implemented an “AND” logic gate, producing a signal only when two specific molecules were present simultaneously.

Significance

• Limitations: Conventional Biosensors are Fragile, expensive, or slow in complex environments.
• Advantages of Whole-Cell Biosensors: Living microbes can self-maintain and repair, but typically produce optical signals that are hard to integrate with portable electronics.
• Innovation in Electrical Output: The new design generates an electrical current, making it directly compatible with low-cost electronic devices.
• Low Cost: Offers a cost-effective, programmable, and durable alternative to traditional enzyme-based biosensors.
• Holds promise for environmental monitoring, water safety, medical diagnostics, and bioelectronic applications.

About Escherichia coli (E. coli)

• Definition: E. coli is a rod-shaped bacterium belonging to the Enterobacteriaceae family, commonly residing in the intestines of humans and other warm-blooded animals. 
• Toxicity: While most strains are harmless or even beneficial, some, such as Shiga toxin-producing E. coli (STEC), can cause serious infections.
• Health Impact: Can trigger urinary tract infections, respiratory illnesses, pneumonia, and in rare cases, acute kidney injury.
  • STEC strains cause foodborne diseases through toxins called Shiga toxins
• Transmission: Mainly via contaminated food and water, including undercooked meat, raw milk, vegetables, and sprouts.

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