Synthetic microbial co-cultures for modular bioelectronic sensing in diverse environments.

Human disruption of ecosystems poses a significant threat to global health, driving the need for low-cost, low-power, and easily deployable sensors for environmental and health monitoring. Microbial bioelectronic sensors are particularly well-suited as they generate electrical signals and can be integrated into compact electronic devices for field deployment over extended periods. However, current engineering strategies for bioelectronic sensors lack modularity, are limited to a few microbial chassis, and depend on specialized instruments for signal detection. Here, we present the electroactive co-culture sensing system (e-COSENS), a plug-and-play platform for bioelectronic sensor development. This system comprises a "sender" bacterium that produces electron mediators in response to analytes and a "receiver" bacterium that utilizes the electron mediators to generate electrical signals via extracellular electron transfer (EET). By modularly swapping the sender bacterium and its associated genetic sensing elements, we achieved bioelectronic sensing of metals, small molecules, and peptides in distinct environmental, food, and human-relevant settings. Moreover, we designed a centimetre-sized bioelectronic device that enables low-cost, portable signal readout from e-COSENS using a household digital multimeter. The e-COSENS platform greatly simplifies the bioelectronic sensor design and opens unprecedented potential for bioelectronic sensor applications.