E. coli Turned into Mercury Sensor

Syllabus: Science & Technology (UPSC Prelims)
Source: The Hindu

Context: Researchers have genetically engineered E. coli bacteria into a mercury sensor that can detect toxic metals in water.

About Escherichia coli (E. coli)

• A rod-shaped bacterium belonging to the Enterobacteriaceae family.
• Found in the intestines of humans and animals.
• Most strains are harmless and aid digestion, but some can cause illness.
• Diseases caused:
  • Some strains cause diarrhoea.
  • Others can lead to urinary tract infections, respiratory illness, pneumonia, and more.
• Transmission: Through contaminated food, water, or contact with infected fecal matter.
• How it makes you sick:
  • Certain strains produce Shiga toxin, which damages the small intestine → diarrhoea.
  • These are known as Shiga toxin-producing E. coli (STEC).
• Symptoms: Fever, persistent or bloody diarrhoea, vomiting.
• Treatment: Usually self-limiting; hydration is essential during illness.
• Reference: Vajiram & Ravi – E. coli

What is this Innovation?

• A living biosensor made using genetically modified E. coli.
• Detects mercury and converts it into an electrical signal readable by simple devices.
• Developed by Imperial College London and Zhejiang University.

Why was it Created?

• To design cheap and self-powered sensors.
• To enable real-time detection of harmful metals like mercury in water.

How Does it Work?

• E. coli engineered to act as a detector.
• Mercury activates a protein (MerR) in the bacteria.
• This triggers production of phenazines, which touch electrodes and generate an electric current.
• More mercury = stronger current, easily read by electronic devices.

Where Can it be Used?

• Safe Drinking Water: Detects mercury contamination.
• Environmental Monitoring: Tracks pollution in rivers, lakes, and industrial areas.
• Public Health: Acts as an early warning system for exposed communities.
• Portable Devices: Works with low-cost, field-ready electronics.
• Synthetic Biology: Expands research in bioelectronics and smart diagnostics.