植物精油的熏蒸抗菌活性及其机理研究

本文采用平板熏蒸法测定六种植物精油在气相状态下对四种常见细菌的最低抑菌浓度(Minimum Inhibitory Concentration,MIC)和最小杀菌浓度(Minimum Bactericidal Concentration,MBC),对效果好的精油进行复配研究并将其应用于小米椒保鲜,通过透射电镜和电导率来阐述肉桂精油熏蒸对大肠杆菌的抗菌机制。结果表明,六种精油中抑菌效果显著的是香茅精油、肉桂精油和罗勒精油,在精油浓度为0.125μL/mL时可以抑制所有的供试菌,而杀菌效果较好的是香茅精油和肉桂精油,除铜绿假单胞菌外,在精油浓度为0.125μL/mL时可杀死其余供试菌。将香茅精油、肉桂精油和罗勒精油进行复配,当三者比例为4:1:8时联合熏蒸抗菌效果最好,复配精油对大肠杆菌和沙门氏菌表现出协同增效作用,而对金黄色葡萄球菌则表现为拮抗作用。GC-MS结果表明,香茅精油的熏蒸抗菌能力主要来自香茅醛、香叶醇和香茅醇;肉桂精油主要来自于肉桂醛;罗勒精油则主要来自于草蒿脑、芳樟醇。当复合精油空间浓度为0.125μL/mL时,对小米椒具有较好的防腐保鲜效果。透镜结果显示经肉桂精油熏蒸后的大...

Study of the Fumigation Antimicrobial Activity and Mechanism of Essential Oil

In this study, the antibacterial effects of six plant essential oils against four common bacteria in the vapor phase was investigated by plate fumigation method with the measurement of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The combination of essential oils with better bactericidal effect was studied and applied to keep fresh of capsicum frutescens. The antibacterial mechanism of cinnamon essential oil against Escherichia coli (E. coli) was also determined by transmission electron microscopy (TEM) and electric conductivity. The results showed that citronella essential oil, cinnamon essential oil and basil essential oil had more significant antibacterial effect, which could inhibit all tested bacteria at the concentration of 0.125 μL/mL. Citronella essential oil and cinnamon essential oil had better bactericidal effect, which could kill all the tested bacteria except Pseudomonas aeruginosa at the concentration of 0.125 μL/mL. Blended essential oils with the ratio of citronella essential oil, cinnamon essential oil and basil essential oil being 4:1:8, demonstrated the best antibacterial activity. The blended essential oils showed synergistic effects on E. coli and Salmonella, but antagonistic effect on Staphylococcus aureues. GC-MS indicated that the antibacterial ability of citronella essential oil mainly came from citronellal, geraniol and citronellol, cinnamon essential oil came from cinnamaldehyde and basil essential oil came from estragole and linalool. The application of blended essential oil in modified atmosphere preservation of capsicum frutescens had a better preservative and fresh-keeping effects when the spatial concentration of blended essential oil was 0.125 μL/mL. TEM showed morphological changes and cell membrane shrinkage of E. coli after fumigation with cinnamon essential oil. The conductivity test showed that the membrane permeability of E. coli increased after fumigation, which resulted in electrolyte leakage. In conclusion, the possible antibacterial mechanism of vapor-phase cinnamon essential oil against E. coli is to change the cell morphology and membrane permeability.