Engineered Bacteria Shine Light On Air Pollution

Detecting indoor air pollutants can safeguard human health, but existing approaches are time consuming, expensive, and require trained technicians. Now, researchers have developed a simple and inexpensive device that uses bioluminescent bacteria to monitor air quality and alert people of potentially unsafe conditions (Anal. Chem. 2015, DOI: 10.1021/ac5038208).

If bacteria encounter hazardous substances in the environment, they launch a system to repair damaged DNA and maintain other functions, says Robert S. Marks of Ben-Gurion University of the Negev, in Israel. By adding the genes that make luciferase—a glow-inducing protein—to the same part of the bacteria’s genome as the microbial repair response, scientists have created bacteria that glow in response to chemicals that are toxic to cells. Marks’s team embedded engineered Escherichia coli in a small, 0.6-mm-diameter cylinder of nutrient-rich gel. This disposable bacterial gel pad was attached to a photomultiplier tube via a light guide, which directs light from the bacteria to the tube. The photomultiplier captures emitted photons and converts them into an electrical signal that the researchers can detect and analyze.

To test the device, the researchers placed it into a 30-m² office, says Marks. Then they mimicked a chemical accident by spilling 2 mL of acetone or up to 10 mL of chloroform in the room. After 40 minutes, the bacterial glow increased four- and 25,000-fold, respectively. In another experiment, the researchers could detect concentrations as low as 10 ppb for a wide range of chemicals, including formaldehyde and methanol. Currently, the device only detects whether a toxic chemical is present in the air, but Marks hopes that by incorporating bacteria with different chemical sensitivities, he may be able to identify chemicals with the device as well.