Yap PS, Krishnan T, Chan KG, Lim SH
Journal of Microbiology and Biotechnology, 2014
The purpose of this study was to investigate the mode of action of the cinnamon bark essential oil (CB) when use singly and in combination with piperacillin on its antimicrobial and synergistic activity against plasmid-conferred multi-drug resistant Escherichia coli J53 R1. Viable count of this combination showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis of the membrane permeabilizing effects of CB on treated cultures through their stability against sodium dodecyl sulfate (SDS) revealed that the essential oils played a role in disrupting the bacterial cell membrane. Scanning electron microscopy analysis and zeta potential measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, reduction in bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed the presence of potential quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry (GC-MS) of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%) and eugenol (6.57%) were found to be the major components in the essential oil. These findings suggest that CB has the potential to reverse bacteria resistance to piperacillin in E. coli J53 R1 and may operate via two mechanisms: alteration of outer membrane permeability and inhibition of bacterial QS.
Yap PS, Krishnan T, Chan KG, et al. Some evidences on the mode of action of Cinnamomum verum bark essential oil, alone and in combination with piperacillin against a multi-drug resistant Escherichia coli strain. J Microbiol Biotechnol. 2014. [Epub ahead of print].