Abstract:

In order to understand the bacteriostatic mechanism of rhizoma coptidis extract （RCE） on Staphylococcus aureus， the mechanism of action of RCE on Staphylococcus aureus was explored through growth curve， oxidative damage experiment， cell wall membrane analysis， protein analysis and DNA analysis. The results showed that RCE had a significant inhibitory effect on Staphylococcus aureus with a minimum inhibitory concentration of 2.60 mg·mL^-1. RCE induced an increase in intracellular reactive oxygen species level of Staphylococcus aureus by 506.90%， an increase in extracellular β-galactosidase activity and nucleic acids by 258.28% and 23.82%， respectively， and also a significant amount of propidium iodide fluorescent staining than that of the control； the amount of total protein synthesis， cellular metabolic vigor and succinic dehydrogenase activity decreased by 30.83%， 30.89% and 54.05%， respectively. Ultraviolet absorption spectra and competitive fluorescence spectra of genomic DNA suggested that the RCE could be either groove-bound or electrostatically bound to Staphylococcus aureus DNA. As the above shows， RCE mainly achieved its bacteriostatic effect by increasing the level of intracellular reactive oxygen species and destroying the integrity and permeability of the cell wall membrane. Above results provided references for the comprehensive development and utilization of rhizoma coptidis and its application in the field of feed supplement.

Key words: Staphylococcus aureus, rhizoma coptidis extract, bacteriostatic mechanism

摘要：

为了解黄连提取物对金黄色葡萄球菌的抑菌机理，通过生长曲线、氧化损伤试验、细胞壁膜分析、蛋白质分析和DNA分析，探讨黄连提取物对金黄色葡萄球菌的作用机制。结果表明，黄连提取物对金黄色葡萄球菌有明显的抑制效果，最小抑菌浓度为2.60 mg·mL^-1。黄连提取物可引起金黄色葡萄球菌胞内活性氧水平增加506.90%，胞外β-半乳糖苷酶活性和核酸含量分别增加258.28%和23.82%，碘化丙啶荧光染色也明显多于对照；总蛋白合成量、细胞代谢活力以及琥珀脱氢酶活性分别降低30.83%、30.89%、54.05%。基因组DNA的紫外吸收光谱和竞争性荧光光谱显示，黄连提取物可以与金黄色葡萄球菌DNA进行小沟结合或静电结合。以上结果表明，黄连提取物主要通过增加胞内活性氧水平，破坏细胞壁膜完整性及通透性来达到抑菌效果。研究结果为黄连的综合开发利用及其在饲料添加剂领域的应用提供借鉴。

关键词: 金黄色葡萄球菌, 黄连提取物, 抑菌机理