| Rapid assessment of cell viability of Lactobacillus delbrueckii subsp. bulgaricus by measurement of intracellular pH in individual cells using fluorescence ratio imaging microscopy. | |
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MedLine Citation:
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PMID: 11999117 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The aim of this study was to investigate if the measurement of intracellular pH (pHi) of individual cells by fluorescence ratio imaging microscopy (FRIM) could be utilized as a rapid method for determining the bacterial viability, using Lactobacillus delbrueckii subsp. bulgaricus as a model organism. Five different standardized cultures with equal cell densities but varying viability were prepared on a trial-to-trial basis by combining aliquots of frozen and lyophilized cells with a 50-fold difference in viability, determined by the ability to form colonies on solid growth media. The acidification of milk and Acidification Power Test were used to determine the activity of these cultures. As expected, the cultures containing a higher proportion of viable cells acidified milk faster and performed better in the Acidification Power Test. All cells were fluorescent after staining with carboxyfluorescein diacetate succinimidyl ester but frozen cells reached higher fluorescence intensities than lyophilized cells. The number of strongly fluorescent cells determined by flow cytometry exceeded the number of viable cells determined by CFU. Analysis of pHi of individual cells by FRIM at an extracellular pH of 6.0 revealed two populations of cells with an average pHi of 6.9 +/- 0.1 and 6.1 +/- 0.1. As the number of cells maintaining a pH-gradient of 0.9 +/- 0.1 correlated well with CFU, we suggest that FRIM can be used as a rapid method for the determination of viability of L. delbrueckii subsp. bulgaricus. Measurement of pHi on a single cell basis is expected to provide accurate prediction of the fermentation performance in a wider range of industrial fermentation. |
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Authors:
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K Björn Rechinger; Henrik Siegumfeldt |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: International journal of food microbiology Volume: 75 ISSN: 0168-1605 ISO Abbreviation: Int. J. Food Microbiol. Publication Date: 2002 May |
Date Detail:
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Created Date: 2002-05-09 Completed Date: 2002-07-30 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8412849 Medline TA: Int J Food Microbiol Country: Netherlands |
Other Details:
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Languages: eng Pagination: 53-60 Citation Subset: IM |
Affiliation:
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Department of Dairy and Food Science, Food Microbiology, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark. br@foss-electric.dk |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Colony Count, Microbial Culture Media Flow Cytometry Fluoresceins / metabolism Hydrogen-Ion Concentration Lactobacillus / chemistry*, cytology*, growth & development Microscopy, Fluorescence / methods Staining and Labeling |
| Chemical | |
Reg. No./Substance:
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0/Culture Media; 0/Fluoresceins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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