The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Yan Long - One of the best experts on this subject based on the ideXlab platform.
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Optimization of staining with SYTO 9/Propidium Iodide: interplay, kinetics and impact on Brevibacillus brevis.
BioTechniques, 2020Co-Authors: Ying Deng, Lili Wang, Yujia Chen, Yan LongAbstract:Fluorophores SYTO 9 and Propidium Iodide (PI) are extensively applied in medicine, food industry and environmental monitoring to assess the viability of bacteria. However, the actual performance of...
C. W. Keevil - One of the best experts on this subject based on the ideXlab platform.
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Validation of SYTO 9/Propidium Iodide Uptake for Rapid Detection of Viable but Noncultivable Legionella pneumophila
Microbial Ecology, 2008Co-Authors: M S Giao, M. J. Vieira, S A Wilks, N F Azevedo, C. W. KeevilAbstract:Legionella pneumophila is an ubiquitous environmental microorganism that can cause Legionnaires’ disease or Pontiac fever. As a waterborne pathogen, it has been found to be resistant to chlorine disinfection and survive in drinking water systems, leading to potential outbreaks of waterborne disease. In this work, the effect of different concentrations of free chlorine was studied (0.2, 0.7, and 1.2 mg l^−1), the cultivability of cells assessed by standard culture techniques (buffered charcoal yeast extract agar plates) and viability using the SYTO 9/Propidium Iodide fluorochrome uptake assay (LIVE/DEAD® Bac Light™). Results demonstrate that L. pneumophila loses cultivability after exposure for 30 min to 0.7 mg l^−1 of free chlorine and in 10 min when the concentration is increased to 1.2 mg l^−1. However, the viability of the cells was only slightly affected even after 30 min exposure to the highest concentration of chlorine; good correlation was obtained between the rapid SYTO 9/Propidium Iodide fluorochrome uptake assay and a longer cocultivation with Acanthamoeba polyphaga assay, confirming that these cells could still recover their cultivability. These results raise new concerns about the assessment of drinking water disinfection efficiency and indicate the necessity of further developing new validated rapid methods, such as the SYTO 9/Propidium Iodide uptake assay, to assess viable but noncultivable L. pneumophila cells in the environment.
Angela Ivask - One of the best experts on this subject based on the ideXlab platform.
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Propidium Iodide staining underestimates viability of adherent bacterial cells
Scientific reports, 2019Co-Authors: Merilin Rosenberg, Nuno F. Azevedo, Angela IvaskAbstract:Combining membrane impermeable DNA-binding stain Propidium Iodide (PI) with membrane-permeable DNA-binding counterstains is a widely used approach for bacterial viability staining. In this paper we show that PI staining of adherent cells in biofilms may significantly underestimate bacterial viability due to the presence of extracellular nucleic acids (eNA). We demonstrate that gram-positive Staphylococcus epidermidis and gram-negative Escherichia coli 24-hour initial biofilms on glass consist of 76 and 96% PI-positive red cells in situ, respectively, even though 68% the cells of either species in these aggregates are metabolically active. Furthermore, 82% of E. coli and 89% S. epidermidis are cultivable after harvesting. Confocal laser scanning microscopy (CLSM) revealed that this false dead layer of red cells is due to a subpopulation of double-stained cells that have green interiors under red coating layer which hints at eNA being stained outside intact membranes. Therefore, viability staining results of adherent cells should always be validated by an alternative method for estimating viability, preferably by cultivation.
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Propidium Iodide staining underestimates viability of adherent bacterial cells
2018Co-Authors: Merilin Rosenberg, Nuno F. Azevedo, Angela IvaskAbstract:Combining membrane impermeable DNA-binding stain Propidium Iodide (PI) with membrane-permeable DNA-binding counterstains is a widely used approach for bacterial viability staining. In this paper we show that PI staining of adherent cells in biofilms may significantly underestimate bacterial viability due to the presence of extracellular nucleic acids. We demonstrate that gram-positive Staphylococcus epidermidis and gram-negative Escherichia coli 24-hour initial biofilms on glass consist of 76 and 96% PI-positive red cells in situ, respectively, even though 68% the cells of either species in these aggregates are metabolically active. Furthermore, 82% of E. coli and 89% S. epidermidis are cultivable after harvesting. Confocal laser scanning microscopy (CLSM) revealed that this false dead layer of red cells is due to a subpopulation of double-stained cells that have green interiors under red coating layer which hints at extracellular DNA (eDNA) being stained outside intact membranes. Therefore, viability staining results of adherent cells should always be validated by an alternative method for estimating viability, preferably by cultivation.
Ying Deng - One of the best experts on this subject based on the ideXlab platform.
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Optimization of staining with SYTO 9/Propidium Iodide: interplay, kinetics and impact on Brevibacillus brevis.
BioTechniques, 2020Co-Authors: Ying Deng, Lili Wang, Yujia Chen, Yan LongAbstract:Fluorophores SYTO 9 and Propidium Iodide (PI) are extensively applied in medicine, food industry and environmental monitoring to assess the viability of bacteria. However, the actual performance of...
M S Giao - One of the best experts on this subject based on the ideXlab platform.
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Validation of SYTO 9/Propidium Iodide Uptake for Rapid Detection of Viable but Noncultivable Legionella pneumophila
Microbial Ecology, 2008Co-Authors: M S Giao, M. J. Vieira, S A Wilks, N F Azevedo, C. W. KeevilAbstract:Legionella pneumophila is an ubiquitous environmental microorganism that can cause Legionnaires’ disease or Pontiac fever. As a waterborne pathogen, it has been found to be resistant to chlorine disinfection and survive in drinking water systems, leading to potential outbreaks of waterborne disease. In this work, the effect of different concentrations of free chlorine was studied (0.2, 0.7, and 1.2 mg l^−1), the cultivability of cells assessed by standard culture techniques (buffered charcoal yeast extract agar plates) and viability using the SYTO 9/Propidium Iodide fluorochrome uptake assay (LIVE/DEAD® Bac Light™). Results demonstrate that L. pneumophila loses cultivability after exposure for 30 min to 0.7 mg l^−1 of free chlorine and in 10 min when the concentration is increased to 1.2 mg l^−1. However, the viability of the cells was only slightly affected even after 30 min exposure to the highest concentration of chlorine; good correlation was obtained between the rapid SYTO 9/Propidium Iodide fluorochrome uptake assay and a longer cocultivation with Acanthamoeba polyphaga assay, confirming that these cells could still recover their cultivability. These results raise new concerns about the assessment of drinking water disinfection efficiency and indicate the necessity of further developing new validated rapid methods, such as the SYTO 9/Propidium Iodide uptake assay, to assess viable but noncultivable L. pneumophila cells in the environment.
