Excitable membrane-potential dynamics in bacteria (FitzHugh-Nagumo model)

Electrical stimulation as a probe of living response is far older than the bacterial work. J. C. Bose (1902) reported electric response in inorganic substances, measured by conductivity variation.¹ In 1906 he wrote that plants and animals both give multiple responses under constant thermal, chemical or electrical stimulus.² He also judged electrical stimulus poorly suited to some experiments, because it tends to cause fatigue and, through polarisation, some tissue change.³ In 1918 he described a retarding effect of electric stimulus on growing specimens.⁴ In 1923 he reported that in one Mimosa specimen, electric stimulus applied 30 mm from the responding pulvinus caused the leaf to fall, giving a velocity of 16 mm per second.⁵ Bose's work concerned plants and inorganic matter, not bacteria.

Stratford and colleagues (2019) sought a conceptual account of distinct responses to an identical electrical stimulus. They used a framework based on the FitzHugh-Nagumo neuron model, which they describe as originally published over half a century earlier and as paradigmatic in neuroscience for its simplicity.⁷ Their extension kept that simplicity. It had two parameters, the resting-state membrane potential and the K+ transmembrane gradient.⁷ The authors say the direction of K+ flux, influx or efflux, depends on these two quantities.⁸

Simulations gave a prediction. An external electrical stimulus causes hyperpolarization in proliferative cells. The same stimulus produces a relaxation response from depolarization in inhibited cells.⁸ The authors tested this prediction experimentally. They report that the stimulus induced hyperpolarization in unperturbed cells and depolarization in inhibited cells.⁶ They propose using this difference to detect proliferative cells, and to tell them from nonproliferative cells, within a minute of stimulation.⁶

Later work links bacterial membrane potential to other cell functions. Hada and colleagues (2026) review efflux pumps of the RND family, such as AcrB. They state that these pumps draw on the proton motive force, so altering the membrane potential affects pump activity.⁹ Citing Whittle and colleagues (2024), they report that Salmonella strains lacking AcrB, or carrying mutations that block proton translocation, show higher membrane potential than wild-type cells.⁹ This concerns resting potential, not electrical stimulation.