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Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment

Decisions regarding microbial risk assessment usually have to be carried out with incomplete information. This is due to the large number of possible scenarios and the lack of specific data for the problem considered. Consequently, risk assessment studies are based on the information obtained with a...

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Autores principales: Garre, Alberto, Egea, Jose A., Iguaz, Asunción, Palop, Alfredo, Fernandez, Pablo S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6066666/
https://www.ncbi.nlm.nih.gov/pubmed/30087669
http://dx.doi.org/10.3389/fmicb.2018.01663
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author Garre, Alberto
Egea, Jose A.
Iguaz, Asunción
Palop, Alfredo
Fernandez, Pablo S.
author_facet Garre, Alberto
Egea, Jose A.
Iguaz, Asunción
Palop, Alfredo
Fernandez, Pablo S.
author_sort Garre, Alberto
collection PubMed
description Decisions regarding microbial risk assessment usually have to be carried out with incomplete information. This is due to the large number of possible scenarios and the lack of specific data for the problem considered. Consequently, risk assessment studies are based on the information obtained with a small number of bacterial cells which are considered the most heat resistant and/or more capable of multiplying during storage. The identification of the most resistant strains is usually based on D and z-values, normally estimated from isothermal experiments. This procedure omits the potential effect that the shape of the dynamic thermal profile applied in industry has on the microbial inactivation. One example of such effects is stress acclimation, which is related to a physiological response of the cells during sub-lethal treatments that increases their resistance. In this article, we use a recently published mathematical model to compare the development of thermal resistance for Escherichia coli K12 MG1655 and E. coli CECT 515 using inactivation data already published for these strains. Based only on the isothermal experiments, E. coli K12 MG1655 would be identified as more resistant to the thermal treatment than the CECT 515 strain in the 50–65°C temperature range. However, we conclude that stress acclimation is strain (and/or media)-dependent; the CECT 515 strain has a higher capacity for developing a stress acclimation than K12 MG1655 (300% increase of the D-value for CECT 515, 50% for K12 MG1655). It, thus, has the potential to be more resistant to the thermal treatment than the K12 MG1655 strain for some conditions allowing acclimation. A methodology is proposed to identify for which conditions this may be the case. After calibrating the model parameters representing acclimation using real experimental data, the applicability of the proposed approach is demonstrated using numerical simulations, showing how the CECT 515 strain can be more resistant for some heating profiles. Consequently, the most resistant bacterial strain to a dynamic heating profile should not be identified based only on isothermal experiments (D- and z-value). The relevance of stress acclimation for the treatment studied should also be evaluated.
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spelling pubmed-60666662018-08-07 Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment Garre, Alberto Egea, Jose A. Iguaz, Asunción Palop, Alfredo Fernandez, Pablo S. Front Microbiol Microbiology Decisions regarding microbial risk assessment usually have to be carried out with incomplete information. This is due to the large number of possible scenarios and the lack of specific data for the problem considered. Consequently, risk assessment studies are based on the information obtained with a small number of bacterial cells which are considered the most heat resistant and/or more capable of multiplying during storage. The identification of the most resistant strains is usually based on D and z-values, normally estimated from isothermal experiments. This procedure omits the potential effect that the shape of the dynamic thermal profile applied in industry has on the microbial inactivation. One example of such effects is stress acclimation, which is related to a physiological response of the cells during sub-lethal treatments that increases their resistance. In this article, we use a recently published mathematical model to compare the development of thermal resistance for Escherichia coli K12 MG1655 and E. coli CECT 515 using inactivation data already published for these strains. Based only on the isothermal experiments, E. coli K12 MG1655 would be identified as more resistant to the thermal treatment than the CECT 515 strain in the 50–65°C temperature range. However, we conclude that stress acclimation is strain (and/or media)-dependent; the CECT 515 strain has a higher capacity for developing a stress acclimation than K12 MG1655 (300% increase of the D-value for CECT 515, 50% for K12 MG1655). It, thus, has the potential to be more resistant to the thermal treatment than the K12 MG1655 strain for some conditions allowing acclimation. A methodology is proposed to identify for which conditions this may be the case. After calibrating the model parameters representing acclimation using real experimental data, the applicability of the proposed approach is demonstrated using numerical simulations, showing how the CECT 515 strain can be more resistant for some heating profiles. Consequently, the most resistant bacterial strain to a dynamic heating profile should not be identified based only on isothermal experiments (D- and z-value). The relevance of stress acclimation for the treatment studied should also be evaluated. Frontiers Media S.A. 2018-07-24 /pmc/articles/PMC6066666/ /pubmed/30087669 http://dx.doi.org/10.3389/fmicb.2018.01663 Text en Copyright © 2018 Garre, Egea, Iguaz, Palop and Fernandez. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Microbiology
Garre, Alberto
Egea, Jose A.
Iguaz, Asunción
Palop, Alfredo
Fernandez, Pablo S.
Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment
title Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment
title_full Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment
title_fullStr Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment
title_full_unstemmed Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment
title_short Relevance of the Induced Stress Resistance When Identifying the Critical Microorganism for Microbial Risk Assessment
title_sort relevance of the induced stress resistance when identifying the critical microorganism for microbial risk assessment
topic Microbiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6066666/
https://www.ncbi.nlm.nih.gov/pubmed/30087669
http://dx.doi.org/10.3389/fmicb.2018.01663
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