Multichannel Bioelectronic Sensing Using Engineered Escherichia coli

Abstract

Whole cell bioelectronic sensors enable the conversion of chemical signals into electrical signals using extracellular electron transfer pathways. However, these sensors use a single extracellular electron pathway as a single electrochemical channel, severely limiting the capacity of the information exchange. To expand the information content, we report a multichannel bioelectronic sensor in which different chemical modules modulate distinct extracellular electron transfer pathways in Escherichia coli. We have introduced two reporting channels into a single Escherichia coli: 1) Mtr pathway from Shewanella oneidensis; 2) riboflavin synthesis pathway from Bacillus subtilis. By upregulating the exogenous riboflavin pathway, we doubled the extracellular flavin concentration. The presence of flavins yielded a distinct electrochemical signal at more negative potentials than the Mtr pathway. To demonstrate multichannel bioelectronic sensing of heavy metals, expression of the Mtr and RF pathways were placed under control of As and Cd responsive promoters. Using a redox-potential-dependent algorithm, multichannel bioelectronic sensors could distinguish As, Cd, and a combination of As and Cd in situ in environmental samples. These accomplishments provide a new platform for multichannel bioelectronic sensors that simultaneously detect different chemicals and expand the information content from biosensors to help safeguard human and environmental health.