Bacteria hyperpolarize in response to oxygen drop

Aerobic microbes use oxygen as a terminal electron acceptor to establish an electrochemical gradient across their cell membranes. While this membrane potential (ΔΨ) is essential for multiple cellular processes, it is unknown if and how it is maintained in bacteria during shifts in oxygen availability. We find that bacteria hyperpolarize in response to drops in oxygen. Focusing on Bacillus subtilis and guided by modeling, we report that hyperpolarization magnitude scales with the degree of electron acceptor deprivation. We find that potassium efflux contributes to the response. Surveying mutants, we uncover genes involved in potassium homeostasis and oxygen stress that contribute to hyperpolarization. We show that hyperpolarization scales with faster growth rates resulting from nutrient type and colony spatial heterogeneity. Finally, we demonstrate that oxygen shift increases susceptibility to antibiotics. Our results demonstrate a conserved link between ΔΨ and oxygen stress, suggesting a common mechanism for responding to shifting oxygen availability.