Bio-Sensors Developed Using E. coli

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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