Synthetic Whole-Cell Bioelectronic Chemical Sensing with In Situ Genetic Computing

Biosensors exploit the capabilities of biological systems to acquire a huge variety of chemical or physical information and convert molecular signals into actionable data. Here we took a bottom-up synthetic biology approach to combine the versatility and programmability of whole-cell bacterial biosensors with the sensitivity of electrochemical sensing devices. We built genetic modules to produce different phenazines and wired these to various sensing and information processing modules. A whole-cell bioelectronic sensor with a T7 RNAP-based signal amplifier was first constructed that detected mercury contaminants below the level of WHO safe limit for drinking water. We demonstrated the modularity and programmability of the sensor design by incorporating Boolean logic computation into a dual-input sensor. We subsequently engineered a sensor strain that can produce two phenazine types, giving a two-channel electrochemical output signal based on the detection of differentiated midpoint potentials. Our modular bioelectronic sensor therefore can be readily adapted for different applications and forms the basis for development of low-cost, field-deployable sensing devices.