Illuminating Bacterial Electrophysiology

Abstract

The revelation that bacteria undergo rapid voltage transients sparked a potential union between the fields of microbiology and electrophysiology. Voltage transients in biology are canonically studied in neuronal and cardiac contexts, where a voltage depolarization induces calcium fluctuations. Using genetically encoded voltage and calcium indicators, we sought to uncover a physiological role for voltage depolarizations in E. coli. We found bacteria are similar to electrically excitable eukaryotic cells; voltage depolarization induces calcium influx, hinting at a potential signaling mechanism. Surprisingly, we found that changing the mechanical environment can trigger calcium influx and also alters gene expression. We hypothesize that, similar to sensory neurons, E. coli mechanosensation is mediated by a voltage-gated calcium channel. Further, we hypothesize that the calcium dynamics we observe mediate the correlated gene expression changes, akin to eukaryotic cells. Understanding how bacteria utilize voltage fluctuations to enact physiological change could lead to the development of novel antibiotics, and potentially give clues as to the origins of voltage as a signal in biology.