Document Detail

Intracellular pH as an indicator of viability and resuscitation of Campylobacter jejuni after decontamination with lactic acid.
MedLine Citation:
PMID:  19720418     Owner:  NLM     Status:  MEDLINE    
The aim of the study was to determine intracellular pH (pH(i)) as an indicator of the physiological state of two Campylobacter jejuni strains (603 and 608) at the single cell level after bactericidal treatment with lactic acid (3% v/v lactic acid, pH 4.0, 0.85% w/v NaCl) and during recovery and survival using Fluorescence Ratio Imaging Microscopy (FRIM). After exposure to lactic acid solution a decline in pH(i) to 5.5 (FRIM detection limit) was observed in the majority of cells (75-100%) within 2 min. The enumeration data revealed that after 2 min of lactic acid exposure, approx. 90% of the initial population became unculturable. In the following 10 min of exposure, a further decrease in the cell count was observed resulting in 3.53 and 3.21 log CFU/ml reduction of culturable cells at the end of the treatment. On the contrary, the FRIM results revealed that the subpopulations with pH(i)>5.5 increased between 2 and 12 min of exposure to lactic acid. Removing the acid stress and incubating the cells suspension under the more favourable conditions resulted in an immediate increase in cell population with pH(i)>pH(ex) for both C. jejuni strains. Further 24 h incubation at 37 degrees C resulted in increased pH(i) and colony count (recovery study). On the contrary, 24 h incubation at suboptimal temperature of 4 degrees C, showed pH(i) decrease to pH(ex)=6.0 (no pH gradient) in the whole population of C. jejuni cells. Rather than dying, cells exposed for longer time (72 and 120 h) to 4 degrees C increased the subpopulation of the cells with positive pH gradient, mostly comprised of the cells with DeltapH>0.5, indicating the ability of C. jejuni cells to regulate their metabolic activity under suboptimal conditions.
Nada Smigic; Andreja Rajkovic; Dennis Sandris Nielsen; Henrik Siegumfeldt; Mieke Uyttendaele; Frank Devlieghere; Nils Arneborg
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-08-04
Journal Detail:
Title:  International journal of food microbiology     Volume:  135     ISSN:  1879-3460     ISO Abbreviation:  Int. J. Food Microbiol.     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-09-28     Completed Date:  2010-01-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8412849     Medline TA:  Int J Food Microbiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  136-43     Citation Subset:  IM    
Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium.
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MeSH Terms
Adaptation, Physiological*
Campylobacter jejuni / growth & development,  physiology*
Colony Count, Microbial
Hydrogen-Ion Concentration*
Lactic Acid*
Microbial Viability*
Microscopy, Fluorescence / methods
Stress, Physiological
Reg. No./Substance:
50-21-5/Lactic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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