Chorianopoulos N G, Lambert R J W, Skandamis P N, Evergetis E T, Haroutounian S A, Nychas G-J E
Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science and Technology, Agricultural University of Athens, Athens, Greece.
J Appl Microbiol. 2006 Apr;100(4):778-86. doi: 10.1111/j.1365-2672.2006.02827.x.
The minimum inhibitory concentration (MIC) of Satureja spinosa essential oil against Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, Salmonella serovar Enteritidis PT4 and Bacillus cereus was comparatively assessed with an established optical density method as well as a novel impedimetric method.
The impedimetric analysis takes into account information of microbial growth, such as detection time, maximum conductance, and slope of the conductance curve. For each pathogen two levels of inoculation were studied, a high (10(5) CFU ml(-1)) and a low level (10(2) CFU ml(-1)). Non-linear regression analysis was used to fit the data using a modification of a previously published model, from which a more exact value can be obtained for the MIC. Both methods gave similar MICs as shown by t-test statistical analysis. Salm. Enteritidis seems to be the least sensitive to the action of S. spinosa essential oil followed by L. monocytogenes, E. coli, B.cereus and Staph. aureus. The MICs of low inoculum were lower than that of high inoculum.
The new impedimetric assay of MIC of essential oils can be considered a reliable rapid method for screening antimicrobial effectiveness of natural additives.
Determination of the minimum inhibitory concentration of an essential oil with the simple conductance technique and further study of the mode of action of its components is a good combination for obtaining additional knowledge for industrial application of such natural additives.
采用既定的光密度法以及一种新型的阻抗法，比较评估刺山柑精油对金黄色葡萄球菌、大肠杆菌O157:H7、单核细胞增生李斯特菌、肠炎沙门氏菌、肠炎沙门氏菌血清型PT4和蜡样芽孢杆菌的最低抑菌浓度（MIC）。
阻抗分析考虑了微生物生长的信息，如检测时间、最大电导率和电导率曲线的斜率。针对每种病原体，研究了两种接种水平，即高接种水平（10⁵ CFU ml⁻¹）和低接种水平（10² CFU ml⁻¹）。使用先前发表模型的改进版，通过非线性回归分析对数据进行拟合，由此可获得更精确的MIC值。经t检验统计分析表明，两种方法得出的MIC值相似。肠炎沙门氏菌似乎对刺山柑精油的作用最不敏感，其次是单核细胞增生李斯特菌、大肠杆菌、蜡样芽孢杆菌和金黄色葡萄球菌。低接种量的MIC低于高接种量的MIC。
精油MIC的新型阻抗测定法可被视为一种可靠的快速方法，用于筛选天然添加剂的抗菌效果。
用简单的电导率技术测定精油的最低抑菌浓度，并进一步研究其成分的作用方式，是获取此类天然添加剂工业应用更多知识的良好组合。
