Antibacterial mechanisms of thyme essential oil nanoemulsions against Escherichia coli O157:H7 and Staphylococcus aureus: Alterations in membrane compositions and characteristics
Antibacterial mechanisms of thyme essential oil nanoemulsions against Escherichia coli O157:H7 and Staphylococcus aureus: Alterations in membrane compositions and characteristics
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DOI：
10.1016/j.ifset.2021.102902
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发表时间：
2021-12-20
影响因子：
6.6
通讯作者：
Guo, Mingming
中科院分区：
文献类型：
--
作者：
He, Qiao;Zhang, Lianjiao;Guo, Mingming
以超声波（US）和高压均质（HPH）法制备的百里香精油纳米乳（TEON）为研究材料，通过最小抑菌浓度（MIC）、最小杀菌浓度（MBC）和时效曲线分析对TEON的抑菌活性进行了评价。与TEON-HPH相比，TEON-US具有更好的抑菌和杀菌效果，这与其具有更好的物理化学特性（包括更小的液滴尺寸和更高的ζ电位）有关。专门针对大肠杆菌O157:H7（革兰氏阴性菌）和金黄色葡萄球菌（革兰氏阳性菌）的细胞膜研究了潜在的抗菌机制。其中，细胞膜崩解，胞质包涵体大量渗漏。此外，膜功能障碍（包括膜电位去极化和流动性降低）可能与暴露于TEONs后脂肪酸组成的改变有关，并最终导致细菌死亡。这些结果揭示了TEONs的抗菌作用模式，为其在食品基质中的应用提供了重要的理论依据。
In this study, the antibacterial activities of thyme essential oil nanoemulsions (TEON) prepared by ultrasonication (US) and high-pressure homogenization (HPH) were evaluated via minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-killing curve analyses. TEON-US presented superior bacteriostatic and bactericidal effects, which was found to be correlated with its better physicochemical characteristics (including smaller droplet size and higher zeta potential) compared to TEON-HPH. The underlying antibacterial mechanisms were specifically investigated targeting cell membranes of Escherichia coli O157:H7 (Gram-negative bacterium) and Staphylococcus aureus (Gram-positive bacterium). Thereinto, membrane disintegrations were observed followed by massive leakage of cytoplasmic inclusions. Furthermore, the membrane dysfunctions (involving membrane potential depolarization and fluidity reduction) were likely associated with the modifications seen in the fatty acid composition upon TEONs exposure, and ultimately causing bacterial death. These results deciphered the mode of antibacterial action of TEONs, providing a critical theoretical basis for their future application in food matrix.