胡桃醌对大肠杆菌细胞膜的作用研究

Effect of Juglone on the Cell Membrane of Escherichia coli

通过考察胡桃醌对大肠杆菌细胞膜的作用来研究胡桃醌的抑菌机理。采用3种不同质量浓度的胡桃醌作用于大肠杆菌后,测定培养液中的相对电导率、蛋白质质量浓度和细胞内外K+、Na+含量的变化,并结合透射电镜图来分析胡桃醌对大肠杆菌细胞膜的影响。结果表明:胡桃醌能够改变大肠杆菌细胞膜的渗透性,大量带电离子和蛋白质外漏;菌体细胞内外K+、Na+含量与空白对照组相比变化显著。透射电镜观察,经胡桃醌作用后菌体细胞被破坏,细胞膜变薄,细胞个体之间界限变模糊,内容物流出。并且,随胡桃醌质量浓度的增加和作用时间的延长,对大肠杆菌细胞膜的破坏越显著。显示胡桃醌的抑菌活性与其对大肠杆菌细胞膜的破坏有直接关系。

Juglone （5-hydroxyl-1,4-naphthalene hydroquinone）, a natural antibacterial compound, has reportedly showed antibacterial effect on many microbial species. However, its antibacterial mechanism has never been reported. In this study, the effect ofjuglone on the cell membrane of Escherichia coli during culture in the presence ofjuglone at various concentrations was evaluated in terms of relative conductivity, protein content, K＋ and Na~ efflux, and also examined under transmission electron microscopy （TEM）. The results showed that juglone increased membrane permeability and therefore resulted in an outflow of charged ions and protein. Compared with the control samples, K＋ and Na＋ concentrations revealed a significant change. TEM observation exhibited that E. coli cells were destroyed by juglone, causing thin cell membrane, blurred cell boundary and outflowed cytoplasm. In addition, increasing juglone concentration could result in more obvious damage to the cell membrane in E. coli. In conclusion, the inhibitory activity of juglone is directly related to its damage to the cell membrane of E. coil