title: New insights in mechanisms of bacterial inactivation by carvacrol.
abstract: OBJECTIVE
  To study the mechanism of bacterial inactivation by carvacrol and the influence of genetic and environmental factors in its antimicrobial activity.
  
  
  RESULTS
  In general, bacterial inactivation by carvacrol was higher in the Gram-positive Listeria monocytogenes than in the Gram-negative Escherichia coli and at acidic pH. At pH 4.0, 25 μl l(-1) of carvacrol for 5 h inactivated 1 and more than 5 log(10) cycles of E. coli and L. monocytogenes populations, respectively. Genetic and environmental factors also influenced cell resistance to carvacrol: rpoS and sigB deletion decreased carvacrol resistance in E. coli and L. monocytogenes, respectively; a heat shock induced a phenomenon of cross-protection to carvacrol treatments. Repair of sublethal injuries in cell envelopes suggested that carvacrol targets lipid fractions and proteins of these structures. This result was corroborated by attenuated total reflectance infrared microspectroscopy analysis.
  
  
  CONCLUSIONS
  This study shows critical genetic and environmental factors, such as rpoS or sigB and heat shocks, and reveals new microbial structures involved in the mechanism of bacterial inactivation by carvacrol.
  
  
  CONCLUSIONS
  A better understanding of the mechanisms of microbial inactivation is of great relevance to design more appropriate carvacrol treatments with high antimicrobial effects.
authors.affiliation: Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Ait-Ouazzou
authors.forename: L
authors.initials: L
authors.lastname: Espina
authors.forename: T K
authors.initials: TK
authors.lastname: Gelaw
authors.forename: S
authors.initials: S
authors.lastname: de Lamo-Castellví
authors.forename: R
authors.initials: R
authors.lastname: Pagán
authors.forename: D
authors.initials: D
authors.lastname: García-Gonzalo
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D002473:Cell Wall / Q000187:drug effects; D015169:Colony Count, Microbial; D000081007:Cymenes; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D018869:Heat-Shock Response; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000235:genetics; D050296:Microbial Viability; D039821:Monoterpenes / Q000494:pharmacology*; D012808:Sigma Factor / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D000081007:Cymenes; D039821:Monoterpenes; C079011:SigB protein, Bacteria; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; C073316:carvacrol