银离子对几种细菌的杀菌效应

Mechanism underlying prolonged antibacterial effect of silver ion

  • 摘要: 由抗生素导致的耐药性问题日益严重,因此新型抗菌药物的研发迫在眉睫。银离子因具有抗菌作用,以及安全、无耐药性、稳定性高等优点而备受关注。为了探究银离子的抗菌机制,本实验选择几种常见水生细菌,研究其对银离子的耐受性和细菌种内、种间的“僵尸效应”(被银离子杀死的细菌可以杀死其他新鲜的细菌),以进一步明确银离子长效杀菌的机理。结果显示,银离子对5种细菌都表现出了明显的生长抑制。同种细菌和异种细菌之间都表现出明显的“僵尸效应”,并且随着银离子浓度的提高,“僵尸效应”的效果越明显。为进一步研究银离子杀菌机制,通过透射电镜观察银离子处理后的嗜水气单胞菌和无乳链球菌,结果显示银离子处理后的细菌出现胞质皱缩,细胞膜呈弥散状态,甚至破裂,细胞内容物外流,最终致使细菌死亡。研究表明,银离子对5种细菌都有明显的生长抑制效应,并发现细菌之间存在“僵尸效应”,可为研发新型的抗菌药物提供参考。

     

    Abstract: Drug resistance mainly caused by the abuse of antibiotics is becoming more and more serious, therefore there is an urgent need to develop novel antibacterial agents. Due to its safety, non-resistance, and high stability, the antibacterial activity of silver ion (Ag+) has attracted the attention of more and more researchers. In order to explore the antibacterial mechanism of Ag+, several common aquatic bacteria (Escherichia coli, Aeromonas hydrophila, Streptococcus agalactiae, Bacillus subtilis, Edwardsiella ictaluri), were used to test the Ag+ tolerance or bactericidal activity and its "zombie effect" (the bacteria killed by Ag+ can kill other fresh bacteria). The results of tolerance experiments of bacteria to Ag+ showed that Ag+ had significant growth inhibition on all the five bacteria. The higher concentration of Ag+, the more apparent "zombie effect" was observed in the same species of bacteria as well as different species of bacteria. To further investigate the mechanism underlying the antibacterial activity of Ag+, the Ag+ treated A. hydrophila and S. agalactiae were observed by transmission electron microscopy (TEM). The TEM results demonstrated that Ag+ could cause the separation of the cytoplasmic membrane (CM) from the cell wall and discharge of cytoplasmic organelles, so it could cause the lysis of the bacterial cell wall. In summary, this study reveals the prolonged antibacterial mechanism of Ag+, which will pave a new way for the development of novel antibacterial agents.

     

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