Electrical signalling beyond diffusion-limited microbial interactions.

Ecological communication is traditionally interpreted through diffusion-limited chemical signalling. Here, we argue that bioelectricity provides a complementary dimension of microbial ecological interaction, arising from ion-driven electrical signalling between responsive cells and extracellular electron transport through redox-active or conductive pathways. These mechanisms operate over distinct physical regimes, with ion-driven signalling mediating information-bearing interactions when electrical or electrochemical perturbations are sensed and decoded by biological recipients, whereas extracellular electron transport enables metabolic and redox coupling. We define "handover distance" as the effective functional interaction range over which a biologically generated electrical or electrochemical perturbation can elicit a measurable response in a biological recipient. In analogy to the phycosphere, which describes the diffusionlimited chemical interaction radius surrounding microorganisms, handover distance provides an experimentally testable means of linking cellular electrophysiology to the spatial range of biological interactions. This Perspective proposes that bioelectrical interactions represent an underappreciated dimension of microbial ecology that complements established chemical communication across complex environments.