葡萄柚籽提取物及其纳米乳对大肠杆菌和金黄色葡萄球菌生物菌膜的抑制作用

目的：研究葡萄柚籽提取物(grapefruitseedextract,GSE)及其纳米乳(grapefruitseedextract nanoemulsion,GNE)对大肠杆菌和金黄色葡萄球菌生物菌膜的抑制作用。方法：分析菌膜黏附菌数变化、胞外聚合物(extracellular polymeric substances,EPS)含量并进行微观结构观察，比较GSE和GNE对两菌菌膜(单种菌膜和混合菌膜)形成的抑制作用和已形成菌膜的清除效果。结果：与对照组相比，1/2最小抑菌浓度(minimum inhibitory concentration,MIC)GSE和GNE可以抑制两菌单种菌膜形成时黏附菌和EPS产生，且对金黄色葡萄球菌的抑制作用更强。扫描电子显微镜(scanning electron microcopy,SEM)和共聚焦激光扫描显微镜(confocal laser scanning microscope,CLSM)所观察到的微观结构变化也显示出GSE和GNE对两菌菌膜形成具有抑制作用。GSE和GNE对已形成菌膜也有良好清除效果，且对金黄色葡萄球菌菌膜的清除作用更强，但混合菌膜...

Inhibitory Effects of Grapefruit Seed Extract and Its Nanoemulsion on Biofilm Formation of Escherichia coli and Staphylococcus aureus

Purpose: To investigate the inhibitory effects of grapefruit seed extract (GSE) and its nanoemulsion (GNE) on biofilm formation of Escherichia coli and Staphylococcus aureus. Methods: The inhibitory effects of GSE and GNE on the formation of single and mixed-species biofilms were explored by analyzing the changes in the number of adherent cells and the content of extracellular polymeric substances (EPS) as well as microstructure observation, and the effectiveness of GSE and GNE in eliminating biofilms formed by E. coli and S. aureus was compared. Results: The number of adherent cells and EPS production during single-species biofilm formation were inhibited by GSE and GNE at 1/2 minimum inhibitory concentration (MIC), and S. aureus was more strongly inhibited. The changes of biofilm microstructure observed under a scanning electron microscope (SEM) and a confocal laser scanning microscope (CLSM) confirmed the inhibitory effect of GSE and GNE on biofilm formation by the two bacteria. GSE and GNE could also eliminate E. coli and S. aureus biofilms, and were more effective for S. aureus biofilm, but the resistance of the mixed-species biofilms was stronger than that of the single-species biofilms. GNE was more effective than GSE in inhibiting biofilm formation and eliminating biofilms. The amount of single-species biofilms formed by the two bacteria decreased by 0.6 (lg (CFU/cm2)) when treated with GNE at 1/2 MIC for 120 h compared with GSE, and the elimination rate of biofilms by 1.8% GNE increased by 7.7%–27.2% compared with GSE. Conclusion: GSE and GNE have inhibitory effect on on biofilm formation of Escherichia coli and Staphylococcus aureus. This study can provide a scientific basis for the application of GSE and GNE in biofilm control.