Bacterial bioelectricity, the first 15 years: developments, tools, and remaining questions

Fifteen years after the first optical recordings of fast cell membrane-potential (“Vm”) transients in Escherichia coli using a genetically encoded rhodopsin-based reporter, bacterial bioelectricity has matured from a provocative observation into a quantitative, multi-scale research program. Early work established that bacterial Vm is dynamic and can exhibit spike-like events correlated with rapid ion efflux, suggesting that electrical state participates in regulating transport and stress responses. Subsequent studies revealed that ion channels can mediate long-range electrical communication in Bacillus subtilis biofilms via propagating K + waves that coordinate metabolic states across millimeter scales. In parallel, theory and experimental work formalized how community heterogeneity and spatial organization determine signal transmission, and how electrical dynamics can influence cell behaviors such as motility and recruitment into biofilms. Most recently, the field has entered a “perturb-and-measure” phase: optical, bioelectronic, and impedance-based platforms now enable controlled stimulation and more mechanistic tests of causality in bacterial electrophysiology, with emerging translational directions in antimicrobial control. Here we review these developments, highlight competing interpretations of bacterial “excitability,” identify key measurement and mechanistic gaps (especially absolute Vm quantification and causal linking to phenotype), and outline future opportunities at the interface of photobiology, bioelectronics, and microbial physiology.