Cell dualism: presence of cells with alternative membrane potentials in growing populations of bacteria and yeasts

Abstract

It is considered that all growing cells, for exception of acidophilic bacteria, have negatively charged inside cytoplasmic membrane (Δψ⁻-cells). Here we show that growing populations of microbial cells contain a small portion of cells with positively charged inside cytoplasmic membrane (Δψ⁺-cells). These cells were detected after simultaneous application of the fluorescent probes for positive membrane potential (anionic dye DIBAC⁻) and membrane integrity (propidium iodide, PI). We found in exponentially growing cell populations of Escherichia coli and Saccharomyces cerevisiae that the content of live Δψ⁻-cells was 93.6 ± 1.8 % for bacteria and 90.4 ± 4.0 % for yeasts and the content of live Δψ⁺-cells was 0.9 ± 0.3 % for bacteria and 2.4 ± 0.7 % for yeasts. Hypothetically, existence of Δψ⁺-cells could be due to short-term, about 1 min for bacteria and 5 min for yeasts, change of membrane potential from negative to positive value during the cell cycle. This change has been shown by the reversions of K⁺, Na⁺, and Ca²⁺ ions fluxes across the cell membrane during synchronous yeast culture. The transformation of Δψ(⁻-cells to Δψ⁺-cells can be explained by slow influx of K⁺ ions into Δψ⁻-cell to the trigger level of K⁺ concentration ("compression of potassium spring"), which is forming "alternative" Δψ⁺-cell for a short period, following with fast efflux of K⁺ ions out of Δψ⁺-cell ("release of potassium spring") returning cell to normal Δψ⁻ state. We anticipate our results to be a starting point to reveal the biological role of cell dualism in form of Δψ⁻- and Δψ⁺- cells.

Trk2 Potassium Transport System in Streptococcus mutans and Its Role in Potassium Homeostasis, Biofilm Formation, and Stress Tolerance

“…We then hypothesized that in low extracellular K ϩ , the intracellular levels of K ϩ could be manipulated to collapse internal pH homeostasis of cells and affect the transmembrane potential. Cells typically maintain a negative intracellular potential, except for acidophilic cells and except during certain phases in the cell cycle when cells undergo "alternate positive potential" (72). The defect in membrane potential of SM⌬trk2 mutants reinforces its phenotypes' requirement of a high K ϩ concentration for cellular functions and pH sensitivity.…”

Cross-limb communication during Xenopus hind-limb regenerative response: non-local bioelectric injury signals

“…S2C). As a result of these control experiments, and in light of the extensive literature implicating DiBAC 4 (3) as a sensor for depolarized cells (Adams and Levin, 2012a,b;Adams et al, 2007Adams et al, , 2016Beane et al, 2011Beane et al, , 2013Blackiston et al, 2011;Chernet and Levin, 2013;Ivanov et al, 2013;Jang et al, 2011;Jia et al, 2013;Oviedo et al, 2008;Pai et al, 2012;Vandenberg et al, 2011;Wolff et al, 2003), we will refer to DiBAC 4 (3) + cells as depolarized in this paper, though additional factors that can contribute to this signal are described in the Discussion section.…”