Ultrastructural studies on antimicrobial efficacy of thyme essential oils on Listeria monocytogenes

作者：Iraj Rasooli, Mohammad Bagher Rezaei, Abdolamir Allameh · 发表于：International Journal of Infectious Diseases · 年份：2006 · DOI：10.1016/j.ijid.2005.05.006 · 被引用次数：174 · 研究领域：Essential Oils and Antimicrobial Activity、Listeria monocytogenes in Food Safety、Insect Pest Control Strategies

OBJECTIVES: Listeria monocytogenes has gained increasing attention as a pathogen of public health importance owing to large numbers of food-borne outbreaks of listeriosis. Because of negative consumer perception of chemical preservatives, attention is shifting towards natural alternatives. Particular interest has been focused on the potential application of plant essential oils. The objective of the present study was to determine ultrastructural changes brought about by essential oils from two types of thyme, Thymus eriocalyx and Thymus x-porlock, on Listeria monocytogenes. MATERIALS AND METHODS: Minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations and bactericidal kinetics of the oils were determined. Listeria monocytogenes were treated with essential oils from two thyme species and observed under a transmission electron microscope. RESULTS: The oils from the above plants were found to be strongly antimicrobial. Analysis of the oils by gas chromatography and gas chromatography/mass spectrometry lead to the identification of 18 and 19 components in T. eriocalyx and T. x-porlock oils, respectively. Listeria monocytogenes treated with essential oils from the two thyme species exhibited a thickened or disrupted cell wall with increased roughness and lack of cytoplasm. CONCLUSION: The antilisterial effects of thyme oil are stronger than the action of electric shocks in combination with nisin reported in the literature. It is concluded that essential oils such as...