Document Detail


Effect of environmental stresses on the mean and distribution of individual cell lag times of Escherichia coli O157:H7.
MedLine Citation:
PMID:  16815581     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of starvation, heat or acid stress on duration of individual cell lag time (tau) and standard deviation (SD) of tau was investigated using Escherichia coli O157:H7. Cells were stressed by exposure to acid (pH 3.5), heat (50 degrees C), or starvation in either glucose-free mineral medium (MOPS), tryptic soy broth (TSB) or Luria broth (LB). Stressed cells were then diluted into wells of a Bioscreen plate to obtain single cells per well. Replicate time to detection (td) values were obtained using the Bioscreen and used to calculate the tau and SD. Significant (P< or =0.05) increases in tau over untreated controls were found for the following treatments: 14 days in acid; 2 h of heating; 3 days starvation in MOPS; and 2 days starvation in either TSB or LB. The largest increase in tau was >2-fold from 2.5 to 5.6 h observed with the heat treatment. MOPS starvation was more detrimental to the cells than was acid treatment over the same time period. A significant increase in SD was found with 21 days acid treatment, and 2 days starvation in either TSB or LB. No significant increase in SD was found for MOPS starvation or heat treatment. Lognormal, Gamma, ExtremeValue and Weibull distributions were fitted to the tau data using BestFit. The results suggest that the Lognormal distribution is suitable for fitting tau data from either stressed or unstressed cells.
Authors:
Yaqin Li; Joseph A Odumeru; Mansel Griffiths; Robin C McKellar
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-07-11
Journal Detail:
Title:  International journal of food microbiology     Volume:  110     ISSN:  0168-1605     ISO Abbreviation:  Int. J. Food Microbiol.     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-07-31     Completed Date:  2006-09-18     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8412849     Medline TA:  Int J Food Microbiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  278-85     Citation Subset:  IM    
Affiliation:
Laboratory Service Division, University of Guelph, 95 Stone Road West, Guelph, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Colony Count, Microbial
Culture Media / chemistry*
Environment
Escherichia coli O157 / growth & development*
Food Microbiology
Hot Temperature*
Hydrogen-Ion Concentration*
Kinetics
Mathematics
Models, Biological*
Models, Statistical
Predictive Value of Tests
Chemical
Reg. No./Substance:
0/Culture Media

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


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