E. coli and the microbiota-gut-brain axis: bioelectrical connection

Abstract

The complex interaction between the gut microbiota and the central nervous system, known as the microbiota-gut-brain (MGB) axis, has generated significant interest in recent years, leading to the emergence of neuromicrobiology as an exciting interdisciplinary field. Among the millions of resident bacteria, Escherichia coli (E. coli) is emerging as a promising probiotic platform for developing strains with the potential to regulate various metabolic and multifactorial diseases. Exploring the communication pathways between E. coli populations and neurons could unveil novel nutritional approaches to target the MGB axis. Here, we track and functionally alter the bioelectrical profile (electroma) within an E. coli population using the voltage-sensitive fluorescent dye DiBAC4(3) and the administration of established neurotransmitter drugs. Our goal is to elucidate the evolution of the bioelectrical profile throughout E. coli growth and its response to the inhibitory neurotransmitter γaminobutyric acid (GABA) and the excitatory neurotransmitter Glutamate (Glu). Furthermore, we assess the impact of neurotransmitter-induced bioelectrical changes on bacterial growth, viability, and cultivability through absorbance measurements, live/dead fluorescent probes, and viable counts. Our results demonstrate significant alterations in the bioelectrical profile of E. coli depending on the growth phase and neurotransmitter exposure, characterized by a decrease in depolarization in both scenarios. Interestingly, neurotransmitters do not affect bacterial viability or cultivability, suggesting that changes in membrane potential are solely attributed to neural stimuli and not to fundamental shifts in bacterial physiology. This investigation expands our comprehension of E. coli's bioelectric behaviour within the gut microbiota and highlights the potential for external stimuli to influence bacterial bioelectrical signalling, offering implications for strategies targeting the MGB axis.