Evaluation of Ultrasound-Induced Damage to Escherichia coli and Staphylococcus aureus by Flow Cytometry and Transmission Electron Microscopy
Evaluation of Ultrasound-Induced Damage to Escherichia coli and Staphylococcus aureus by Flow Cytometry and Transmission Electron Microscopy
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通过流式细胞术和透射电子显微镜评估超声波对大肠杆菌和金黄色葡萄球菌的损伤
DOI：
10.1128/aem.03080-15
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发表时间：
2016-03-01
影响因子：
4.4
通讯作者：
Ding, Tian
中科院分区：
文献类型：
--
作者：
Li, Jiao;Ahn, Juhee;Ding, Tian
超声波作为一种非热杀菌技术，在食品保鲜领域引起了人们极大的兴趣。在这项研究中，流式细胞仪和透射电子显微镜研究超声诱导的损伤大肠杆菌和金黄色葡萄球菌。对于流式细胞术研究，用碘化丙啶（PI）或羧基荧光素二乙酸酯（cFDA）进行的单染色显示，超声处理通过损害膜完整性、使细胞内酯酶失活和抑制代谢性能而引起细胞死亡。结果表明，超声波损伤是独立的初始细菌浓度，而根据细菌的种类不同的细胞损伤的机制。革兰氏阴性菌E.在大肠杆菌中，超声波首先作用于外膜而不是细胞质膜。基于双染色结果，我们推断超声处理可能是一个全有或全无的过程：被超声破碎和解体的细胞不能复活，这可以被认为是超声相对于其他非热技术的优势。透射电子显微镜研究表明，超声波引起的损伤机制是多靶点失活，涉及细胞壁，细胞质膜和内部结构。了解超声波的不可逆抑菌作用，对其在食品工业中的进一步应用具有重要意义。
ABSTRACT As a nonthermal sterilization technique, ultrasound has attracted great interest in the field of food preservation. In this study, flow cytometry and transmission electron microscopy were employed to investigate ultrasound-induced damage to Escherichia coli and Staphylococcus aureus. For flow cytometry studies, single staining with propidium iodide (PI) or carboxyfluorescein diacetate (cFDA) revealed that ultrasound treatment caused cell death by compromising membrane integrity, inactivating intracellular esterases, and inhibiting metabolic performance. The results showed that ultrasound damage was independent of initial bacterial concentrations, while the mechanism of cellular damage differed according to the bacterial species. For the Gram-negative bacterium E. coli, ultrasound worked first on the outer membrane rather than the cytoplasmic membrane. Based on the double-staining results, we inferred that ultrasound treatment might be an all-or-nothing process: cells ruptured and disintegrated by ultrasound cannot be revived, which can be considered an advantage of ultrasound over other nonthermal techniques. Transmission electron microscopy studies revealed that the mechanism of ultrasound-induced damage was multitarget inactivation, involving the cell wall, cytoplasmic membrane, and inner structure. Understanding of the irreversible antibacterial action of ultrasound has great significance for its further utilization in the food industry.