Scientists turn Escherichia coli bacteria into a mercury sensor , Pg11

Key Highlights:

• Researchers from Imperial College London and Zhejiang University have engineered Escherichia coli bacteria into self-powered chemical sensors.
• The engineered bacteria can detect specific compounds and convert them into electrical signals, interfacing directly with electronics.
• One biosensor detected arabinose, a plant sugar, while another detected mercury ions in water, even at concentrations below the WHO safety limit.
• The team also demonstrated an 'AND' logic gate inside E. coli, producing a signal only when two specific molecules were present together.

Detailed Insights:

• Traditional biosensors are often fragile, costly, and slow, whereas whole-cell biosensors using living microorganisms can self-repair and operate in contaminated samples.
• The modular biosensor design includes a sensing module, an information processing module, and an output module that produces phenazines.
• The mercury sensor uses a genetic amplifier to enhance sensitivity, detecting mercury at just 25 nanomoles, below the WHO safety limit, within three hours.
• This research establishes a proof of concept for living, electronically integrated biosensors capable of detecting compounds, processing signals, and supplying data.

Scientific/Technical Concepts Involved:

• Escherichia coli (E. coli): A common bacterium used in biological research due to its simple genetic structure and rapid reproduction.
• Voltammetry: An electrochemical technique used to measure the current produced by a chemical reaction, providing quantitative data about the substance being analyzed.
• Phenazines: Nitrogen-containing organic molecules produced by the engineered bacteria that can be measured using voltammetry to detect the presence of specific compounds.