Thymus maroccanus essential oil, a membranotropic compound active on Gram-negative bacteria and resistant isolates
Article first published online: 28 AUG 2012
© 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 113, Issue 5, pages 1120–1129, November 2012
How to Cite
Fadli, M., Chevalier, J., Bolla, J.-M., Mezrioui, N.-E., Hassani, L. and Pages, J.-M. (2012), Thymus maroccanus essential oil, a membranotropic compound active on Gram-negative bacteria and resistant isolates. Journal of Applied Microbiology, 113: 1120–1129. doi: 10.1111/j.1365-2672.2012.05401.x
- Issue published online: 17 OCT 2012
- Article first published online: 28 AUG 2012
- Accepted manuscript online: 19 JUL 2012 03:51AM EST
- Manuscript Accepted: 13 JUL 2012
- Manuscript Revised: 8 JUN 2012
- Manuscript Received: 27 FEB 2012
- inner and outer membrane;
- membrane permeability;
- multidrug resistance;
- protein release;
- Thymus maroccanus
The effects of Thymus maroccanus essential oil (EO) on the integrity of the cell membranes and the permeability of the outer membrane (OM) and inner membrane (IM) of Escherichia coli, Enterobacter aerogenes and Salmonella enterica Typhimurium were investigated.
Methods and Results
The bacterial release of intracellular proteins, cytoplasmic β-galactosidase and periplasmic β-lactamase induced by T. maroccanus EO was compared to the membranotropic activity of polymyxin B (PB) known as an effective permeabilizer of the membrane of Gram-negative bacteria. Results showed that T. maroccanus EO increased the permeability of the OM and IM of studied bacteria and induced the release of intracellular proteins into the external medium.
The effect of T. maroccanus EO on the outer membrane was comparable to that of PB, and both T. maroccanus EO and PB induce similar levels of β-lactamase release. In addition, it also promoted the release of the cytoplasmic β-galactosidase. Moreover, the lipopolysaccharide molecules and the overexpression of efflux pumps seem to play a crucial role in the level of susceptibility of studied bacteria to the permeabilizing effect of T. maroccanus EO.
Significance and Impact of Study
These results demonstrate that T. maroccanus EO can restore antibiotic activity by targeting the two bacterial membranes and would be attractive candidates for developing new adjuvants for combating resistant Gram-negative bacteria.