绞股蓝内生真菌对金黄色葡萄球菌的抗菌机制

Antibacterial mechanisms of endophytic fungi from Gynostemma pentaphyllum on Staphylococcus aureus

目的研究绞股蓝内生真菌JY25对金黄色葡萄球菌的抗菌机制。方法采用二倍稀释法测定发酵液最小抑菌浓度(MIC)和最小杀菌浓度(MBC);MIC浓度的发酵液对金黄色葡萄球菌生长的抑制作用;扫描电镜法观察发酵液对菌体形态结构的影响;同时,测定β-半乳糖酶、碱性磷酸酶和电导率检测发酵液对细胞膜和细胞壁的影响;电泳分析发酵液对蛋白质合成和核酸结构的影响。结果 JY25发酵液对金黄色葡萄球菌的MIC为0.875g/L、MBC为7g/L;MIC浓度的发酵液使细菌对数生长期延迟8h,菌体形态发生严重的畸形和破损,破坏其生物膜的形成;随着作用时间的延长,β-半乳糖酶含量和电导率增加,菌体蛋白质合成异常,未检测到碱性磷酸酶和核酸结构变化。结论绞股蓝内生真菌JY25主要是破坏细菌细胞膜及影响细菌蛋白质合成发挥抗菌作用,进而破坏其生物膜的形成延迟耐药性的产生。

Objective To investigate the antibacterial mechanisms of endophytic fungi named JY25 from Gynostemma pentaphyllum on S. aureus. Methods The method of double dilution was adopted to determine the minimum inhibitory concentration （MIC） and minimum bactericidal concentration （MBC） of fermentation filtrate to S. aureus. Then, the fermentation filtrate with MIC concentrations was used to inhibit the growth of S. aureus, and the effect of S. aureus morphology were observed by scanning electron microscope. Meanwhile, β-galactosidase, alkaline phosphatase and conductivity were employed for the determination of fermentation filtrate on S. aureus cell membrane and cell wall. Finally, the effects of protein synthesis and nucleic acid structure of S. aureus were detected by gel electrophoresis. Results The results showed that MIC of JY25 fermentation filtrate to S. aureus was 0.875g/L, MBC was 7 g/L, and the fermentation filtrate with MIC concentration could delay the logarithmic growth of S. aureus up to 8 h, with severe deformity and damage of cell morphology, destroy the biofilm formation. With the extension of treating time, both the β-galactosidase activity and conductivity increased, and the protein synthesis was abnormal. The alkaline phosphatase and nucleic acid structure did not be change. Conclusion The antibacterial mechanisms of JY25 endophytic fungi from Gynostemma pentaphyllum on S. aureus are related with damaging the cell membranes and impacting protein synthesis, and then damage the biofilm formation for delayed the development of drug resistance.