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Updated: May 21, 2026
An Automated Differential Nuclear Staining Assay for Accurate Determination of Mitocan Cytotoxicity
Published on: May 12, 2020
Sodium chloride affects propidium monoazide action to distinguish viable cells
Valdir C Barth1, Fernanda Cattani, Carlos A S Ferreira
1Laboratório de Imunologia e Microbiologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre/RS CEP 90619-900, Brazil.
Abstract:
Propidium monoazide (PMA) is a DNA-intercalating agent used to selectively detect DNA from viable cells by polymerase chain reaction (PCR). Here, we report that high concentrations (>5%) of sodium chloride (NaCl) prevents PMA from inhibiting DNA amplification from dead cells. Moreover, Halobacterium salinarum was unable to maintain cell integrity in solutions containing less than 15% NaCl, indicating that extreme halophilic microorganisms may not resist the concentration range in which PMA fully acts. We conclude that NaCl, but not pH, directly affects the efficiency of PMA treatment, limiting its use for cell viability assessment of halophiles and in hypersaline samples.
Insights
High salt concentrations interfere with propidium monoazide (PMA) effectiveness in distinguishing viable cells via PCR. This limits PMA
Area of Science:
- Microbiology
- Molecular Biology
- Biotechnology
Background:
- Propidium monoazide (PMA) is a vital DNA-intercalating dye used to differentiate between viable and dead cells in molecular analyses.
- PMA selectively enters cells with compromised membranes (dead cells), where it binds to DNA and prevents amplification by polymerase chain reaction (PCR).
- Accurate viability assessment is crucial in various fields, including environmental microbiology and clinical diagnostics.
Purpose of the Study:
- To investigate the impact of sodium chloride (NaCl) concentration on the efficacy of PMA in viability assays.
- To determine the tolerance limits of extreme halophilic microorganisms, such as Halobacterium salinarum, to NaCl concentrations relevant to PMA treatment.
- To assess the influence of pH and NaCl on PMA's ability to inhibit DNA amplification from dead cells.
Main Methods:
- Experiments were conducted using varying concentrations of sodium chloride (NaCl) and different pH levels.
- The effectiveness of propidium monoazide (PMA) in preventing DNA amplification from dead cells was assessed using polymerase chain reaction (PCR).
- Cell integrity of Halobacterium salinarum was monitored in solutions with different NaCl concentrations.
Main Results:
- High concentrations of sodium chloride (>5%) were found to inhibit the effectiveness of PMA in preventing DNA amplification from dead cells.
- Halobacterium salinarum demonstrated sensitivity to low NaCl concentrations (<15%), compromising cell integrity.
- Sodium chloride concentration directly influenced PMA efficiency, whereas pH did not show a significant effect within the tested ranges.
Conclusions:
- The efficacy of PMA for cell viability assessment is significantly compromised in the presence of high NaCl concentrations.
- Extreme halophilic microorganisms may not be compatible with PMA-based viability assays due to their specific salt tolerance requirements.
- PMA treatment is limited in hypersaline environments and for studying halophilic microbes due to NaCl interference.
