From red to green: the propidium iodide-permeable membrane of Shewanella decolorationis S12 is repairable

Abstract

Viability is a common issue of concern in almost all microbial processes. Fluorescence-based assays are extensively used in microbial viability assessment, especially for mixed-species samples or biofilms. Propidium iodide (PI) is the most frequently used fluorescence indicator for cell viability based on the membrane permeability. Our results showed that the accumulation of succinate from fumarate respiration could induce PI-permeability in Shewanella decolorationis biofilm cells. Confocal laser scanning microscope further showed that the PI-permeable membrane could be repaired in situ when the extracellular succinate was eliminated by switching fumarate respiration to electrode respiration. Simultaneously with the membrane repair, the electrode respiring capacity of the originally PI-permeable cells was recovered. Agar-colony counts suggested that a major portion of the repaired cells were viable but nonculturable (VBNC). The results evidenced that S. decolorationis S12 has the capacity to repair PI-permeable membranes which suggests a reevaluation of the fate and function of the PI-permeable bacteria and expanded our knowledge on the flexibility of bacterial survival status in harsh environments.

Mechanisms of Action for Antimicrobial Peptides With Antibacterial and Antibiofilm Functions

“…Other dyes such as Sytox Green or PI can be used to establish whether HDPs damage cytoplasmic membranes and interact with intracellular nucleic acids (Sträuber and Müller, 2010;Davey and Hexley, 2011;Wenzel et al, 2015;Yang Y. et al, 2015;Pulido et al, 2016;Yasir et al, 2019). These dyes penetrate through membranes in which pores are present and can be used to probe differences in pore size and structure.…”

Determination of live and dead Komagataeibacter xylinus cells and first attempt at precise control of inoculation in nanocellulose production

“…However, PI uptake is actually dependent on the physiological state of the bacterial cells (Shi et al, 2007), and a recent study (Kirchhoff and Cypionka, 2017) found that the membrane potential of cells could also affect the uptake of PI in viable cells, which would lead to the erroneous conclusion that PI-stained cells were dead. It has also been reported that the accumulation of succinate from fumarate respiration could induce PI permeability in Shewanella decolorationis biofilm cells, and the PI-permeable membrane could be repaired in situ when the extracellular succinate was eliminated by switching fumarate respiration to electrode respiration (Yang et al, 2015). To eliminate possible errors, the cell membrane potential of K. xylinus strains and the uptake of PI in viable cells requires further investigation.…”

Antimicrobial effects of Photodynamic Therapy to gram negative bacteria envelope revealed by Cryo-electron tomography

“…Numerous reports 47,48,49 has been using Propidium iodide (PI) to characterize the dead or nonviable cells from living prokaryotic cells, as PI only stain cells with irreparably damaged membranes that can be described as nonviable or dead. The results of this study showed an increase of bacteria stained with PI after 1hour penicillin treatment and also after aPDT.…”