This Article Full Text Full Text (PDF) Other Versions of this Article: AEM.00340-07v1 73/14/4484    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Burt, S. A. Articles by Veldhuizen, E. J. A. Search for Related Content PubMed PubMed Citation Articles by Burt, S. A. Articles by Veldhuizen, E. J. A. Agricola Articles by Burt, S. A. Articles by Veldhuizen, E. J. A.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, July 2007, p. 4484-4490, Vol. 73, No. 14
0099-2240/07/$08.00+0     doi:10.1128/AEM.00340-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Carvacrol Induces Heat Shock Protein 60 and Inhibits Synthesis of Flagellin in Escherichia coli O157:H7

Institute for Risk Assessment Sciences, Division of Veterinary Public Health,¹ Department of Infectious Diseases and Immunology,² Department of Farm Animal Health,³ Centre for Cell Imaging, Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands⁴

Received 12 February 2007/ Accepted 15 May 2007

The essential oils of oregano and thyme are active against a number of food-borne pathogens, such as Escherichia coli O157:H7. Carvacrol is one of the major antibacterial components of these oils, and p-cymene is thought to be its precursor in the plant. The effects of carvacrol and p-cymene on protein synthesis in E. coli O157:H7 ATCC 43895 cells were investigated. Bacteria were grown overnight in Mueller-Hinton broth with a sublethal concentration of carvacrol or p-cymene, and their protein compositions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and confirmed by Western blotting. The presence of 1 mM carvacrol during overnight incubation caused E. coli O157:H7 to produce significant amounts of heat shock protein 60 (HSP60) (GroEL) (P < 0.05) and inhibited the synthesis of flagellin highly significantly (P < 0.001), causing cells to be aflagellate and therefore nonmotile. The amounts of HSP70 (DnaK) were not significantly affected. p-Cymene at 1 mM or 10 mM did not induce HSP60 or HSP70 in significant amounts and did not have a significant effect on flagellar synthesis. Neither carvacrol (0.3, 0.5, 0.8, or 1 mM) nor p-cymene (0.3, 0.5, or 0.8 mM) treatment of cells in the mid-exponential growth phase induced significant amounts of HSP60 or HSP70 within 3 h, although numerical increases of HSP60 were observed. Motility decreased with increasing concentrations of both compounds, but existing flagella were not shed. This study is the first to demonstrate that essential oil components induce HSP60 in bacteria and that overnight incubation with carvacrol prevents the development of flagella in E. coli O157:H7.

Published ahead of print on 25 May 2007.