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Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance

Persistent bacteria are a microbial subpopulation that, exposed to bactericidal treatment, is killed at a slower rate than the rest of the population they are part of. They can be triggered either following stress or stochastically without external signals. The hallmark of persistent bacteria is the...

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Autores principales: Nalbone, Luca, Sorrentino, Giorgia, Giarratana, Filippo, Schiopu-Mariean, Aurelian, Ziino, Graziella, Giuffrida, Alessandro
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PAGEPress Publications, Pavia, Italy 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10102965/
https://www.ncbi.nlm.nih.gov/pubmed/37064513
http://dx.doi.org/10.4081/ijfs.2023.10880
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author Nalbone, Luca
Sorrentino, Giorgia
Giarratana, Filippo
Schiopu-Mariean, Aurelian
Ziino, Graziella
Giuffrida, Alessandro
author_facet Nalbone, Luca
Sorrentino, Giorgia
Giarratana, Filippo
Schiopu-Mariean, Aurelian
Ziino, Graziella
Giuffrida, Alessandro
author_sort Nalbone, Luca
collection PubMed
description Persistent bacteria are a microbial subpopulation that, exposed to bactericidal treatment, is killed at a slower rate than the rest of the population they are part of. They can be triggered either following stress or stochastically without external signals. The hallmark of persistent bacteria is the biphasic killing curve, a sign that, within a microbial population, two subpopulations are inactivated at a different rate. Furthermore, when plated into a fresh medium and in the absence of stressors, persistent bacteria typically remain in the lag phase longer before resuming active replication. This study aims to evaluate in vitro whether the formation of persistent cells in a strain of Listeria monocytogenes can be triggered by exposure to osmotic stress and if this phenomenon can increase heat resistance in the bacterial population. In a first experiment, the lag time distribution of a L. monocytogenes strain grown in a 6% NaCl broth was evaluated using the software ScanLag. A stationary phase broth culture was inoculated on agar plates placed on an office scanner inside an incubator at 37°C. The plates were scanned every 20’ for 4 days and the acquired images were automatically elaborated with the aid of MatLab software in order to evaluate the appearance times of every single colony. The experiment was also carried out on a control culture obtained by growing the strain in the broth without salt. In a second experiment, the same broth cultures, after proper dilutions to rebalance NaCl concentration, were subjected to a heat treatment at 51°C and the death curves obtained were parameterized using the GinaFit system. Results showed that the lag phase of 31.40% of the salt culture colonies was long enough to suppose the formation of persistent bacteria. Analyses of the thermal survival curves showed that the shoulder and tail model was the one that best represented the inactivation trend of the salt culture, unlike the control culture, whose trend was essentially linear. Results of the present study show how exposure to salt could induce the formation of persistent bacteria in a L. monocytogenes strain. The last raises concerns as persistent cells may not only be undetected with common analytical techniques but they even show a greater heat resistance.
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spelling pubmed-101029652023-04-15 Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance Nalbone, Luca Sorrentino, Giorgia Giarratana, Filippo Schiopu-Mariean, Aurelian Ziino, Graziella Giuffrida, Alessandro Ital J Food Saf Article Persistent bacteria are a microbial subpopulation that, exposed to bactericidal treatment, is killed at a slower rate than the rest of the population they are part of. They can be triggered either following stress or stochastically without external signals. The hallmark of persistent bacteria is the biphasic killing curve, a sign that, within a microbial population, two subpopulations are inactivated at a different rate. Furthermore, when plated into a fresh medium and in the absence of stressors, persistent bacteria typically remain in the lag phase longer before resuming active replication. This study aims to evaluate in vitro whether the formation of persistent cells in a strain of Listeria monocytogenes can be triggered by exposure to osmotic stress and if this phenomenon can increase heat resistance in the bacterial population. In a first experiment, the lag time distribution of a L. monocytogenes strain grown in a 6% NaCl broth was evaluated using the software ScanLag. A stationary phase broth culture was inoculated on agar plates placed on an office scanner inside an incubator at 37°C. The plates were scanned every 20’ for 4 days and the acquired images were automatically elaborated with the aid of MatLab software in order to evaluate the appearance times of every single colony. The experiment was also carried out on a control culture obtained by growing the strain in the broth without salt. In a second experiment, the same broth cultures, after proper dilutions to rebalance NaCl concentration, were subjected to a heat treatment at 51°C and the death curves obtained were parameterized using the GinaFit system. Results showed that the lag phase of 31.40% of the salt culture colonies was long enough to suppose the formation of persistent bacteria. Analyses of the thermal survival curves showed that the shoulder and tail model was the one that best represented the inactivation trend of the salt culture, unlike the control culture, whose trend was essentially linear. Results of the present study show how exposure to salt could induce the formation of persistent bacteria in a L. monocytogenes strain. The last raises concerns as persistent cells may not only be undetected with common analytical techniques but they even show a greater heat resistance. PAGEPress Publications, Pavia, Italy 2023-03-08 /pmc/articles/PMC10102965/ /pubmed/37064513 http://dx.doi.org/10.4081/ijfs.2023.10880 Text en ©Copyright: the Author(s) https://creativecommons.org/licenses/by-nc/4.0/This article is distributed under the terms of the Creative Commons Attribution Noncommercial License (by-nc 4.0) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
spellingShingle Article
Nalbone, Luca
Sorrentino, Giorgia
Giarratana, Filippo
Schiopu-Mariean, Aurelian
Ziino, Graziella
Giuffrida, Alessandro
Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance
title Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance
title_full Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance
title_fullStr Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance
title_full_unstemmed Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance
title_short Effects of osmotic stress on Listeria monocytogenes ATCC 7644: persistent cells and heat resistance
title_sort effects of osmotic stress on listeria monocytogenes atcc 7644: persistent cells and heat resistance
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10102965/
https://www.ncbi.nlm.nih.gov/pubmed/37064513
http://dx.doi.org/10.4081/ijfs.2023.10880
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