新疆家蚕抗菌肽抗菌作用的超微结构观察及抗菌机理初探

为探讨基因工程表达的新疆家蚕(Bombyx mori)抗菌肽(cecropin-XJ)的抗菌机制,通过紫外分光光度法研究抗菌肽的抑菌动力学,并采用透射电镜观察抗菌肽作用于金黄色葡萄球菌(Staphylococcus aureus)后的超微结构,对抗菌肽抗菌机理进行初步探讨。结果表明,抗菌肽抑菌作用比较明显,抗菌肽的活性与作用时间有关。抗菌肽可能是通过"桶-板"模式渗透细胞膜,从而影响细胞膜的结构和功能,使细胞膜形成许多孔道,增强了金黄色葡萄球菌细胞的通透性,造成细胞内的原生质扩散,并从孔道向胞外渗漏,影响了细菌的代谢系统,从而起到抑菌、杀菌作用。抗菌肽使金黄色葡萄球菌细胞内容物大量渗漏而死亡,死亡细胞的细胞壁保持完整,表明细胞膜是抗菌肽作用的主要靶位点。

Antimicrobial Effects and Antimicrobial Mechanism of Antimicrobial Peptides from Xinjiang Silkworm

The purpose of this study was to understand the antimicrobial effects of cecropin-XJ expressed by genetic engineering from Xinjiang Silkworm Bombyx mori.To further characterize the antimicrobial activity of cecropin-XJ,antimicrobial curve was drawn.Ultrastructural observation of Staphylococcus aureus treated with cecropin-XJ was also performed.It was showed that the ability of cecropin-XJ to kill S.aureus was effective and time-dependent.It might be through the "barrel-stave pore" mechanism that cecropin-XJ quickly penetrated and damaged the cell membrane.And then cecropin-XJ affected cytoplasmic membrane,disturbed the ordered arrangement of membrane lipid,and changed permeability of cytoplasmic membrane,leading to the leaking out of cytoplasmic contents.Finally,the affected S.aureus died due to leakage of the cell contents.The cell wall kept intact after cecropin-XJ treatment,suggesting that cecropin-XJ does not damage cell wall.These results indicate that cytoplasmic membrane is the main target attacked by cecropin-XJ.