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Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration

(+)-limonene is a lipophilic antimicrobial compound, extracted from citrus fruits' essential oils, that is used as a flavouring agent and organic solvent by the food industry. A recent study has proposed a common and controversial mechanism of cell death for bactericidal antibiotics, in which h...

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Autores principales: Chueca, Beatriz, Pagán, Rafael, García-Gonzalo, Diego
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3976388/
https://www.ncbi.nlm.nih.gov/pubmed/24705541
http://dx.doi.org/10.1371/journal.pone.0094072
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author Chueca, Beatriz
Pagán, Rafael
García-Gonzalo, Diego
author_facet Chueca, Beatriz
Pagán, Rafael
García-Gonzalo, Diego
author_sort Chueca, Beatriz
collection PubMed
description (+)-limonene is a lipophilic antimicrobial compound, extracted from citrus fruits' essential oils, that is used as a flavouring agent and organic solvent by the food industry. A recent study has proposed a common and controversial mechanism of cell death for bactericidal antibiotics, in which hydroxyl radicals ultimately inactivated cells. Our objective was to determine whether the mechanism of Escherichia coli MG1655 inactivation by (+)-limonene follows that of bactericidal antibiotics. A treatment with 2,000 μL/L (+)-limonene inactivated 4 log(10) cycles of exponentially growing E. coli cells in 3 hours. On one hand, an increase of cell survival in the ΔacnB mutant (deficient in a TCA cycle enzyme), or in the presence of 2,2′-dipyridyl (inhibitor of Fenton reaction by iron chelation), thiourea, or cysteamine (hydroxyl radical scavengers) was observed. Moreover, the ΔrecA mutant (deficient in an enzyme involved in SOS response to DNA damage) was more sensitive to (+)-limonene. Thus, this indirect evidence indicates that the mechanism of exponentially growing E. coli cells inactivation by 2,000 μL/L (+)-limonene is due to the TCA cycle and Fenton-mediated hydroxyl radical formation that caused oxidative DNA damage, as observed for bactericidal drugs. However, several differences have been observed between the proposed mechanism for bactericidal drugs and for (+)-limonene. In this regard, our results demonstrated that E. coli inactivation was influenced by its physiological state and the drug's concentration: experiments with stationary-phase cells or 4,000 μL/L (+)-limonene uncovered a different mechanism of cell death, likely unrelated to hydroxyl radicals. Our research has also shown that drug's concentration is an important factor influencing the mechanism of bacterial inactivation by antibiotics, such as kanamycin. These results might help in improving and spreading the use of (+)-limonene as an antimicrobial compound, and in clarifying the controversy about the mechanism of inactivation by bactericidal antibiotics.
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spelling pubmed-39763882014-04-08 Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration Chueca, Beatriz Pagán, Rafael García-Gonzalo, Diego PLoS One Research Article (+)-limonene is a lipophilic antimicrobial compound, extracted from citrus fruits' essential oils, that is used as a flavouring agent and organic solvent by the food industry. A recent study has proposed a common and controversial mechanism of cell death for bactericidal antibiotics, in which hydroxyl radicals ultimately inactivated cells. Our objective was to determine whether the mechanism of Escherichia coli MG1655 inactivation by (+)-limonene follows that of bactericidal antibiotics. A treatment with 2,000 μL/L (+)-limonene inactivated 4 log(10) cycles of exponentially growing E. coli cells in 3 hours. On one hand, an increase of cell survival in the ΔacnB mutant (deficient in a TCA cycle enzyme), or in the presence of 2,2′-dipyridyl (inhibitor of Fenton reaction by iron chelation), thiourea, or cysteamine (hydroxyl radical scavengers) was observed. Moreover, the ΔrecA mutant (deficient in an enzyme involved in SOS response to DNA damage) was more sensitive to (+)-limonene. Thus, this indirect evidence indicates that the mechanism of exponentially growing E. coli cells inactivation by 2,000 μL/L (+)-limonene is due to the TCA cycle and Fenton-mediated hydroxyl radical formation that caused oxidative DNA damage, as observed for bactericidal drugs. However, several differences have been observed between the proposed mechanism for bactericidal drugs and for (+)-limonene. In this regard, our results demonstrated that E. coli inactivation was influenced by its physiological state and the drug's concentration: experiments with stationary-phase cells or 4,000 μL/L (+)-limonene uncovered a different mechanism of cell death, likely unrelated to hydroxyl radicals. Our research has also shown that drug's concentration is an important factor influencing the mechanism of bacterial inactivation by antibiotics, such as kanamycin. These results might help in improving and spreading the use of (+)-limonene as an antimicrobial compound, and in clarifying the controversy about the mechanism of inactivation by bactericidal antibiotics. Public Library of Science 2014-04-04 /pmc/articles/PMC3976388/ /pubmed/24705541 http://dx.doi.org/10.1371/journal.pone.0094072 Text en © 2014 Chueca et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Chueca, Beatriz
Pagán, Rafael
García-Gonzalo, Diego
Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration
title Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration
title_full Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration
title_fullStr Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration
title_full_unstemmed Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration
title_short Differential Mechanism of Escherichia coli Inactivation by (+)-Limonene as a Function of Cell Physiological State and Drug's Concentration
title_sort differential mechanism of escherichia coli inactivation by (+)-limonene as a function of cell physiological state and drug's concentration
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3976388/
https://www.ncbi.nlm.nih.gov/pubmed/24705541
http://dx.doi.org/10.1371/journal.pone.0094072
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