Christine Payne1
Duke University1
Cells generate a -10 mV to -100 mV electrical potential across the plasma membrane driven by an ion gradient. This resting membrane potential, in comparison to the action potentials of neurons and muscle cells, is present in all cells, including bacteria. A fundamental understanding of bacterial electrophysiology would lead to new methods for the control of engineered living materials, as well as significant advances in synthetic biology, cell growth in industrial bioreactors, and screening of anti-bacterial agents. Recent research in the Payne Lab is aimed at understanding bioelectricity in bacteria guided by questions of heterogeneity and cell growth with applications in materials science.The resting membrane potential of individual cells within a population is highly heterogeneous. In addition to cell-level heterogeneity, we also observe temporal heterogeneity with 2% of individual cells showing short bursts of hyperpolarization, referred to as “spiking.” We have developed methods to image and control resting membrane potential, simultaneously, on the single cell level to determine the underlying source of both the cellular and temporal heterogeneity. We use blue light, which can be patterned, to suppress cell growth in certain regions, creating patterned bacteria, in a way that is not possible using diffusible reagents that affect all cells equally. Blue light-mediated hyperpolarization is coupled with a range of cellular responses including generation of reactive oxygen species, altered enzymatic activity, and changes in membrane permeability, in addition to the inherent heterogeneity of this system. Our experiments are aimed at decoupling these cellular responses to determine what factors drive the associated decrease in cell growth. We hope these experiments will provide new insights in the growing field of bacterial electrophysiology.