# Metabolic basis of brain-like electrical signalling in bacterial communities

## TL;DR

This paper explores how bacterial biofilms use electrical signals mediated by potassium waves, linking metabolic stress transmission to brain-like electrical phenomena, supported by a new mathematical model and experimental validation.

## Contribution

Introduces a spatially-extended mathematical model combining metabolism and electrophysiology in bacterial biofilms, validated through experiments, revealing potassium waves as stress transmission mechanisms.

## Key findings

- Metabolic stress propagates via potassium waves in biofilms.
- Electrical signalling in bacteria resembles cortical spreading depression.
- Model validated by environmental and genetic perturbations.

## Abstract

Information processing in the mammalian brain relies on a careful regulation of the membrane potential dynamics of its constituent neurons, which propagates across the neuronal tissue via electrical signalling. We recently reported the existence of electrical signalling in a much simpler organism, the bacterium Bacillus subtilis. In dense bacterial communities known as biofilms, nutrient-deprived B. subtilis cells in the interior of the colony use electrical communication to transmit stress signals to the periphery, which interfere with the growth of peripheral cells and reduce nutrient consumption, thereby relieving stress from the interior. Here we explicitly address the interplay between metabolism and electrophysiology in bacterial biofilms, by introducing a spatially-extended mathematical model that combines the metabolic and electrical components of the phenomenon in a discretised reaction-diffusion scheme. The model is experimentally validated by environmental and genetic perturbations, and confirms that metabolic stress is transmitted through the bacterial population via a potassium wave. Interestingly, this behaviour is reminiscent of cortical spreading depression in the brain, characterised by a wave of electrical activity mediated by potassium diffusion that has been linked to various neurological disorders, calling for future studies on the evolutionary link between the two phenomena.