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

Whole-cell bioelectronic sensors are particularly well-suited for environmental and health monitoring as they can be integrated into compact electronic devices for field deployment over extended periods. However, current engineering strategies lack modularity, are limited to a few microbial chassis and depend on specialized instruments for signal detection. We present the electroactive co-culture sensing system (e-COSENS), a plug-and-play system for whole-cell bioelectronic sensor development. Here a 'sender' bacterium produces electron mediators in response to analytes and a 'receiver' bacterium utilizes the electron mediators to generate electrical signals via extracellular electron transfer. Modularly swapping the sender bacterium and its associated genetic sensing elements achieved bioelectronic sensing of metals, small molecules and peptides in distinct environments, such as urban waterways, milk, saliva and microbial communities. We designed a centimeter-sized bioelectronic device for portable signal readout using a household digital multimeter. The e-COSENS system simplifies the whole-cell bioelectronic sensor design and expands the potential of bioelectronic sensor applications.