Real-time environmental monitoring of contaminants using living electronic sensors

Real-time chemical sensing is needed to counter the global threats posed by pollution. We combine synthetic biology and materials engineering to develop a living bioelectronic sensor platform with minute detection times. Escherichia coli was programmed to reduce an electrode in a chemical-dependent manner using a modular, eight-component, synthetic electron transport chain. This strain produced significantly more current upon exposure to thiosulfate, an anion that causes microbial blooms. Incorporating a protein switch into the synthetic pathway and encapsulation of microbes with electrodes and conductive nanomaterials yielded a living bioelectronic sensor that could detect an endocrine disruptor within two minutes in riverine water, implicating the signal as mass transfer limited. These findings provide a new platform for miniature, low-power sensors that safeguard ecological and human health. One Sentence Summary Chemicals are detected electrically using an allosterically-regulated electron transfer pathway in designer microbes. ### Competing Interest Statement J.J.S., J.T.A., and G.N.B. have submitted a patent application (No 16/186,226) covering the use of fragmented proteins as chemical-dependent electron carriers, entitled Regulating electron flow using fragmented proteins.