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Limits of propidium iodide as a cell viability indicator for environmental bacteria
Author(s) -
Shi Lei,
Günther Susanne,
Hübschmann Thomas,
Wick Lukas Y.,
Harms Hauke,
Müller Susann
Publication year - 2007
Publication title -
cytometry part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.316
H-Index - 90
eISSN - 1552-4930
pISSN - 1552-4922
DOI - 10.1002/cyto.a.20402
Subject(s) - propidium iodide , bacteria , viability assay , pi , biology , staining , vital stain , cell growth , sphingomonas , flow cytometry , microbiology and biotechnology , cell , biochemistry , apoptosis , programmed cell death , genetics , pseudomonas
Background: Viability measurements of individual bacteria are applied in various scopes of research and industry using approaches where propidium iodide (PI) serves as dead cell indicator. The reliability of PI uptake as a cell viability indicator for dead (PI permeable) and viable (PI impermeable) bacteria was tested using two soil bacteria, the gram − Sphingomonas sp. LB126 and the gram + Mycobacterium frederiksbergense LB501T. Methods: Bacterial proliferation activities observed viaDAPI and Hoechst 33342 staining were linked to the energy charge and the proportion of dead cells as obtained by diOC 6 (3)‐staining and PI‐uptake, respectively. Calibration and verification experiments were performed using batch cultures grown on different substrates. Results: PI uptake depended on the physiological state of the bacterial cells. Unexpectedly, up to 40% of both strains were stained by PI during early exponential growth on glucose when compared to 2–5% of cells in the early stationary phase of growth. Conclusions: The results question the utility of PI as a universal indicator for the viability of (environmental) bacteria. It rather appears that in addition to nonviable cells, PI also stains growing cells of Sphingomonas sp. and M. frederiksbergense during a short period of their life cycle. © 2007 International Society for Analytical Cytology