茶多酚对金黄色葡萄球菌和铜绿假单胞菌的抑菌机理

Antimicrobial Mechanisms of Tea Polyphenol Against Staphyloccocus aureus and Pseudomonas aeruginosa

摘要:

以革兰氏阳性的金黄色葡萄球菌和革兰氏阴性的铜绿假单胞菌为试验菌, 通过测定茶多酚与两种菌作用前后细菌培养液的电导率和可溶性总糖的变化, 以及菌体在磷代谢和蛋白质表达方面的变化, 初步阐明了茶多酚对这两种菌的抑菌机理。研究结果表明, 茶多酚对金黄色葡萄球菌和铜绿假单胞菌均有抑菌活性, 但对金黄色葡萄球菌的抑菌活性更强。经茶多酚处理后, 细菌培养液的电导率和总糖浓度均增大, 表明了茶多酚可破坏细胞膜的结构、导致细胞通透性增加, 进而使细胞内容物外泄。另一方面, 经茶多酚处理后的两种菌对磷的消耗量降低, 以致严重影响了核酸、磷脂等细胞重要成分的合成以及能量代谢; 通过SDS-PAGE分析, 证实茶多酚可以阻碍细菌蛋白质的正常表达, 以致影响其细胞的结构组成以及酶的催化活性, 最终导致细菌正常生理功能的丧失。

Abstract:

The antimicrobial mechanisms of tea polyphenol against Gram-positive S. aureus and Gram-negative P. aeruginosa were investigated by determining the changes in electric conductivity and total sugar concentration of broth for bacteria treated by tea polyphenol, as well as the changes in phosphorous metabolism and protein expression of bacteria. As the results showed, tea polyphenol had antimicrobial activity against S. aureus and P. aeruginosa, but stronger against the former. The facts that the electric conductivity and total sugar concentration of microbial broth increased indicated that tea polyphenol could damage the structure of cell membrane, which resulted in the increase of permeability of cell membrane and release of cell components. Besides, the consumption of phosphorous decreased in the tea-polyphenol-treated bacteria, which seriously influenced the synthesis of important cell components such as nucleic acid and phospholipid and energy metabolism. SDS-PAGE assay demonstrated that tea polyphenol could block the protein expression in bacteria, which influenced the cell structure composition and catalyzing activity of enzyme, and finally leading to the lost of normal physiological function of bacterium.