Mechanism of action of Melaleuca armillaris (Sol. Ex Gaertu) Sm. essential oil on six LAB strains as assessed by multiparametric flow cytometry and automated microtiter-based assay
Mechanism of action of Melaleuca armillaris (Sol. Ex Gaertu) Sm. essential oil on six LAB strains as assessed by multiparametric flow cytometry and automated microtiter-based assay
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DOI：
10.1016/j.foodchem.2008.04.044
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发表时间：
2008-12-01
期刊：
影响因子：
8.8
通讯作者：
Hamdi, Moktar
中科院分区：
文献类型：
--
作者：
Hayouni, El Akrem;Bouix, Marielle;Hamdi, Moktar
关于精油（EOs）对乳酸菌（LAB）的作用，无论是人类胃肠道微生物群还是工业过程中涉及的乳酸菌，我们所知甚少。经GC和GC/MS分析，鉴定出68种化合物，占蜜环千层油的99.6%。桉叶油醇（1,8-桉叶油脑）是主要化合物（68.9%），主要成分为氧化单萜烯组分（77.3%）。先用圆盘扩散法检测其抗乳酸菌活性。在第二阶段，使用自动微滴法（Bioscreen C）建立每个菌株在增加EO浓度（0.25、2.5、5和25 μ g/ml）下孵育的时间存活动力学。抑菌或杀菌效果取决于所研究的菌株和EO的应用浓度。动力学的数学模型表明，随着蜜环菌EO浓度的增加，生长滞后期延长（0.69% ~ 97.5%），生长速度和最终细胞密度均降低。我们注意到不同菌株的变化。采用多参数流式细胞术（结合二醋酸羧酸荧光素（cFDA）和碘化丙啶（PI）荧光探针）对每个样本培养物进行双染色，以区分活细胞、死细胞和应激细胞。在3天的培养过程中，通过量化每个亚种群的相对百分比来评估每个菌株在蜜环乳杆菌EO浓度增加时的行为。结果显示不同模式的亚种群揭示了细胞行为的动态变化。这可能是由于在整个潜伏期内EO成分对细胞生理特性的不同影响。本研究证明，多参数流式细胞术是一种方便、快速的评估LAB活力的工具，且与板计数结果具有良好的相关性。该研究有助于了解如何充分利用乳酸菌作为益生菌或潜在的候选菌来改善食品卫生和保证食品质量；即当它们与天然防腐剂（如EOs）相关联时。(c) 2008 Elsevier Ltd.版权所有。
Little is known concerning the effects of essential oils (EOs) against lactic acid bacteria (LAB), either of the human gastrointestinal microflora or those involved in industrial processes. GC and GC/MS analysis of Melaleuca armillaris EO resulted in the identification of 68 compounds comprising 99.6% of the oil. Eucalyptol (1,8-cineole) was the major compound (68.9%) and the composition was largely dominated by the oxygenated monoterpenes fraction (77.3%). The anti-LAB activities of the EO were first checked by the disc diffusion assay. In a second phase, time-survival kinetics of each strain incubated with increasing concentrations of the EO (0.25, 2.5, 5 and 25 mu g/ml) were established using an automated microtiter assay (Bioscreen C). Bacteriostatic or bactericidal effects were noticed depending on the studied strain and on the applied concentration of the EO. The mathematical modelling of the kinetics showed that in presence of increasing concentrations of M. armillaris EO, the lag phases of growth were extended (0.69%-97.5%) and both the growth rate and final cell density were reduced. Variations depending on the strain were noticed.Live/dead assays of the multiparametric flow cytometry technique (combining carboxyfluorescein diacetate (cFDA) and propidium iodide (PI) fluorescent probes) were performed by dual staining of each sample culture to differentiate viable, dead and stressed cells. The behaviour of each strain, in presence of increasing concentrations of M. armillaris EO, was evaluated by quantifying the relative percentages of each subpopulation throughout 3 days of culture. Results displayed disparate patterns of subpopulations which revealed dynamic changes in cell behaviour. This is probably due to disparate influences of the EO components on cellular physiological properties throughout the incubation period. This study proved that multiparametric flow cytometry was a convenient and rapid tool to evaluate the viability of LAB, and was well correlated with plate count results. Such study could be useful to understand how to fully take advantage of LAB as probiotics or as potential candidates to improve food hygiene and to assure food quality; namely when they are associated with natural preservatives such as EOs. (c) 2008 Elsevier Ltd. All rights reserved.