家蝇幼虫分泌型抗菌肽对大肠埃希菌抑制作用

Anti-Escherichica coli effect of antibacterial peptides from Musca domestica larvae secretion

目的探讨家蝇幼虫分泌型抗菌肽的抗菌机制。方法利用透射电镜、十二烷基硫酸钠(SDS)-聚丙烯酰胺凝胶电泳(PAGE)及流式细胞仪等技术初步探索了家蝇幼虫分泌型抗菌肽对大肠埃希菌作用机理。结果经20、40及80μg/mL抗菌肽作用后,大肠埃希菌液的A570值分别增加了0.170、0.032、-0.030,对照组增加了0.363;菌体外胞内酶含量各组分别增加0.148、0.230、0.324,对照组无变化;电镜观察显示抗菌肽可使菌体皱缩,细胞内容物外泄;SDS-PAGE检测发现,作用后菌体的某些蛋白条带浓度降低或消失,有新的条带出现;流式细胞仪显示抗菌肽作用后处于细胞周期中复制期(R期)的细菌量只占总数的11.89%,而对照组占45.25%,比实验组高33%。结论家蝇幼虫分泌型抗菌肽可通过改变细菌细胞膜的通透性,抑制细菌某些蛋白的合成等发挥抗菌作用。

Objective To explore anti-Escherichia coli（E.coli） mechanism of antibacterial peptides from Musca domestica larvae secretion.Methods Electron microscope,sodium dodecyl sulfonate-polyacylate gel electrophoresis（SDS-PAGE）,and flow cytometry were used to study the anti-E.coli mechanism of antibacterial peptide extracted from housefly（Musca domestica） larvae.Results The bacterial number decreased obviously and the endoenzyme leaked out after the treatment of antibacterial peptide.Transmission electron microscope showed that the bacterial cells shrinked and became smaller and thinner.The cell contents of E.coli leaked out.SDS-PAGE electrophoregram showed that some of the solubility proteins of the bacterium diminished or even vanished and some new protein bands appeared.Cell cycle was affected and the count of bacteria increased in phase I but reduced in phase R（11.89% vs 45.25%） compared to that of the control.And the E.coli went into declining phase directly instead of normal logarithmic phase.Conclusion The permeability of cellular membrane of bacteria and the synthesis of protein associated with growth and cleavage of bacteria were changed by the antibacterial peptide.