Bacteria-powered bioelectronic sensor detects chemicals in liquids

Researchers at Rice University have developed a novel bioelectronic sensor that harnesses living bacteria to detect specific chemicals in liquids by generating electrical signals. This sensor addresses longstanding challenges in microbial bioelectronics, such as the instability and toxicity of electron mediators that shuttle electrons between bacteria and electrodes in liquid environments. The team created a soft hydrogel made from chitosan—a natural polymer from crustacean shells—that traps active bacteria close to the electrode while allowing liquids to flow through. The chitosan was chemically modified to anchor redox mediators, enabling stable electron transfer and maintaining a robust electronic connection. The researchers demonstrated the sensor’s capability by engineering a strain of the probiotic bacterium L. plantarum to detect sakacin P, an antimicrobial peptide used as a food preservative, in milk. When exposed to sakacin P, the bacteria produced a measurable electrical current within hours, which was transmitted through the hydrogel to the electrode. Because the hydrogel and bacteria are safe, renewable, and commonly