Document Detail

Heat and acid tolerance responses of Listeria monocytogenes as affected by sequential exposure to hurdles during growth.
MedLine Citation:
PMID:  19681263     Owner:  NLM     Status:  MEDLINE    
This study aimed to evaluate the effects of the level and sequence of hurdles, applied during growth, on the subsequent heat and acid tolerances of a 10-strain composite of Listeria monocytogenes. Individual strains were grown in glucose-free tryptic soy broth with 0.6% yeast extract (TSBYE-G). Then cultures were mixed and inoculated in fresh TSBYE-G (0.5% NaCl, pH 7.42; control), TSBYE-G that was supplemented with 3% NaCl (3.5% NaCl in total), or TSBYE-G with pH adjusted to 6.01 or 5.04 with lactic acid and incubated at 30 degrees C for 24 h. Furthermore, the culture composite was exposed to the following five combinations of double sequential hurdles (12 h in each at 30 degrees C): NaCl then pH 6.01, NaCl then pH 5.04, pH 7.42 then NaCl, pH 5.04 then NaCl, and pH 6.01 then NaCl. The heat and acid tolerances of the culture were assessed at 57 degrees C (for 2 h) and at pH 3.5 (for 7 h), respectively, in TSBYE-G. No significant (P > or = 0.05) differences in thermotolerance were observed among cultures exposed to various stresses. In contrast, the acid resistance followed the order: pH 6.01 = NaCl > NaCl then pH 5.04 > pH 6.01 then NaCl = pH 5.04 > pH 5.04 then NaCl > pH 7.42 then NaCl > control. The results suggest that exposure of L. monocytogenes to NaCl and low pH during growth may not affect its heat (57 degrees C) tolerance, but it may increase its acid (pH 3.5) resistance, depending on the sequence and intensity of the applied stresses.
Panagiotis N Skandamis; Jarret D Stopforth; Yohan Yoon; Patricia A Kendall; John N Sofos
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of food protection     Volume:  72     ISSN:  0362-028X     ISO Abbreviation:  J. Food Prot.     Publication Date:  2009 Jul 
Date Detail:
Created Date:  2009-08-17     Completed Date:  2009-09-01     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703944     Medline TA:  J Food Prot     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1412-8     Citation Subset:  IM    
Center for Meat Safety and Quality and Food Safety Cluster, Department of Animal Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
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MeSH Terms
Adaptation, Physiological*
Colony Count, Microbial
Food Contamination / prevention & control
Food Handling / methods*
Hot Temperature*
Hydrogen-Ion Concentration
Listeria monocytogenes / drug effects,  growth & development,  physiology*
Microbial Sensitivity Tests
Osmolar Concentration
Sodium Chloride / pharmacology*
Time Factors
Reg. No./Substance:
7647-14-5/Sodium Chloride

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

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