Whole-genome sequencing and genetic analysis reveal novel stress responses to individual constituents of essential oils in Escherichia coli

Article Article scientifique Article Whole-genome sequencing and genetic analysis reveal novel stress responses to individual constituents of essential oils in Escherichia coli eng 2018 author Chueca Beatriz author Renzoni Adriana Maria 134435 author Berdejo Martinez Daniel 909612 author Pagán Rafael author Kelley William 28396 author García-Gonzalo Diego e02538-17 10.1128/AEM.02538-17 29374037 0099-2240 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5861813/ Food preservation by the use of essential oils (EOs) is being extensively studied because of the antimicrobial properties of their individual constituents (ICs). Three resistant mutants (termed CAR, CIT, and LIM) of Escherichia coli MG1655 were selected by subculturing with the ICs carvacrol, citral, and (+)-limonene oxide, respectively. These derivative strains showed increased MIC values of ICs and concomitantly enhanced resistance to various antibiotics (ampicillin, trimethoprim, chloramphenicol, tetracycline, kanamycin, novobiocin, norfloxacin, cephalexin, and nalidixic acid) compared to those for the parental strain (wild type [WT]). Whole-genome sequencing (WGS) of these hyperresistant strains permitted the identification of single nucleotide polymorphisms (SNPs) and deletions in comparison to the WT. In order to analyze the contribution of these mutations to the increased antimicrobial resistance detected in hyperresistant strains, derivative strains were constructed by allelic reversion. A role of the SoxR D137Y missense mutation in CAR was confirmed by growth in the presence of some ICs and antibiotics and by its tolerance to ICs but not to lethal heat treatments. In CIT, increased resistance relied on contributions by several detected SNPs, resulting in a frameshift in MarR and an in-frame GyrB ΔG157 mutation. Finally, both the insertion resulting in an AcrR frameshift and large chromosomal deletions found in LIM were correlated with the hyperresistant phenotype of this strain. The nature of the obtained mutants suggests intriguing links to cellular defense mechanisms previously implicated in antibiotic resistance.IMPORTANCE The antimicrobial efficacy of ICs has been proven over the years, together with their potential to improve traditional heat treatments by reducing treatment intensity and, consequently, adverse effects on food quality. However, the mechanisms of bacterial inactivation by ICs are still not well understood, in contrast to antibiotics. We performed WGS of three E. coli strains that are hyperresistant to ICs. The information provided detailed insight into the mechanisms of bacterial resistance arising from exposure to carvacrol, citral, and (+)-limonene oxide. Future experiments will undoubtedly yield additional insights into genes and pathways contributing to the acquisition of endogenous resistance to ICs. Acyclic Monoterpenes Anti-Bacterial Agents/pharmacology Cyclohexane Monoterpenes Cymenes Drug Resistance Bacterial/genetics Escherichia coli/drug effects/genetics/physiology Food Preservation Microbial Sensitivity Tests Monoterpenes/pharmacology Oils Volatile/pharmacology Stress Physiological Whole Genome Sequencing Dewey 616 Swiss National Science Foundation Staphylococcus aureus Environmental Sensing Systems 310030_146540 CH Project funding 54 Département de microbiologie et médecine moléculaire 21B 56 Département de médecine 221 false 1281 Endoribonucleases : des outils pour le diagnostic des pathogènes 1004 400 Virologie clinique 668 Applied and Environmental Microbiology 84 7 84af97d6-4db6-41ad-9d9c-46b1f15dee24 Article (Published version) Restricted Whole-Genome_sequencing_genetic_analysis_reveal_novel_stress_responses_individual_constituents_essential_oils_Escherichia_coli.pdf 926942 application/pdf restrictedAccess Faculté de médecine / Section de médecine fondamentale / Département de microbiologie et médecine moléculaire Faculté de médecine / Section de médecine clinique / Département de médecine

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Whole-genome sequencing and genetic analysis reveal novel stress responses to individual constituents of essential oils in Escherichia coli	Applied and Environmental Microbiology			2018	273	0

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Berdejo Martinez, Daniel