Multichannel bioelectronic sensing using engineered Escherichia coli

Abstract

To advance environmental health and hazard detection, researchers have developed whole-cell bioelectronic sensors by engineering extracellular electron transfer to be dependent on an analyte¹. However, these sensors regulate a single electron transfer pathway as an electrochemical channel, limiting the sensing information to a single analyte. We have developed a multichannel bioelectronic sensor where different chemicals regulate distinct extracellular electron transfer pathways within a single Escherichia coli cell. One channel utilizes the flavin synthesis pathway from Bacillus subtilis² and is controlled by a cadmium-responsive promoter. Another channel, the Mtr pathway from Shewanella oneidensis³, is controlled by an arsenite-responsive promoter and activates cytochrome CymA expression^{4, 5}. We exploit the differing redox potentials of the two extracellular electron transfer pathways⁶ to develop a redox-potential-dependent algorithm that efficiently converts biological signals into 2-bit binary outputs. This enables our bioelectronic sensor to detect and differentiate heavy metals at EPA limits. When deployed in complex environmental water samples with lower electroactivities, our sensor effectively and accurately encodes 2-bit binary signals across various analyte conditions. Thus, our multichannel bioelectronic sensor advances the field through simultaneous detection of different chemicals by a single cell, significantly expanding information transmission and helping to safeguard human and environmental health.