Programming Electronic Communication in Microbial Consortia for Environmental Sensing

Microbial extracellular electron transfer (EET) has been rewired by synthetic biology to develop bioelectronic sensors that can detect environmental stimuli and generate electrical signals. These sensors have been successfully employed to rapidly detect pollutants in the environment. However, prior works have been restricted to a few EET model organisms, limiting the sensor design spectrum and the deployable environments. We recently indicated that the probiotic bacterium Lactiplantibacillus plantarum can use the naphthoquinone DHNA secreted by quinone-producing bacteria to perform EET and generate electrical current proportional to DHNA concentrations. Inspired by these discoveries, we develop new bioelectronic sensing strategies by programming the quinone-mediated electronic communication in microbial consortia. We create synthetic co-cultures capable of EET by inoculating L. plantarum with a DHNA-producing bacterium, such as Escherichia coli or Lactococcus lactis. We then engineer DHNA as the signal intermediate for bioelectronic sensing by controlling DHNA synthesis with genetic circuits. When the analyte is present, E. coli or L. lactis secrete DHNA as the signal amplifier, which mediates EET in L. plantarum, resulting in the generation of electrical currents. Using this strategy, we achieve bioelectronic sensing of antimicrobial peptides, organic compounds, reactive oxygen species, and heavy metals. This system holds intrinsic modularity on the strain and genetic levels and can be adapted for sensing other analytes of interest for electrical outputs. Taken together, we demonstrate the potential of rewiring EET in microbial consortia for bioelectronic sensing and communication. These co-cultured based bioelectronic sensors could play a vital role in environmental, food, and health monitoring.