Electrically induced bacterial membrane-potential dynamics correspond to cellular proliferation capacity

Area of Science:

• Microbiology
• Electrophysiology
• Cell Biology

Background:

• Bacterial membrane potential dynamics are crucial for intra- and intercellular electrical signaling and cellular proliferation.
• The influence of cellular proliferative capacity on responses to external electrical stimuli remains largely unexplored.

Purpose of the Study:

• To investigate the impact of cellular proliferation on bacterial responses to electrical stimuli.
• To develop a method for simultaneous electrical stimulation and single-cell membrane potential monitoring in bacteria.

Main Methods:

• Development of a bespoke apparatus for exogenous electrical stimulation and single-cell time-lapse microscopy of bacteria.
• Utilizing model organisms *Bacillus subtilis* and *Escherichia coli*.
• Employing measurements of intracellular K+ and K+ channel deletion, alongside a modified FitzHugh-Nagumo neuron model.

Main Results:

• Identical electrical stimuli induced opposite membrane polarization dynamics (hyperpolarization vs. depolarization) depending on cellular proliferation state.
• Hyperpolarization in unperturbed cells was attributed to K+ efflux via K+ channels.
• Pre-exposure to specific light wavelengths or treatments (antibiotics, protonophore, alcohol) shifted the resting membrane potential, leading to depolarization upon electrical stimulation.

Conclusions:

• Bacterial membrane potential dynamics are sensitive to proliferative capacity and external conditions.
• Electrically induced membrane potential changes offer a novel method for rapid bacterial detection and antimicrobial sensitivity testing at the single-cell level.