昆虫病原线虫共生菌胞内外蛋白的提取及杀虫活性比较

Comparison of Toxicity between Extracellular and Intracellular Proteins of Entomopathogenic Nematode Symbiotic Bacteria against Helicoverpa armigera

通过超声波破碎、硫酸铵盐析等方法从10株昆虫病原线虫共生菌的发酵液中分离出各菌株的胞内和胞外蛋白,测定各蛋白样品含量及其对棉铃虫初孵幼虫的生长抑制毒性,并用Native-PAGE和SDS-PAGE对各粗蛋白组分进行初步分析。结果表明有7个菌株的胞内和胞外蛋白对棉铃虫初孵幼虫生长均显示出不同程度的抑制生长活性。其中以嗜线虫致病杆菌3个菌株CB6、All和Bw活性最强,其胞内蛋白的活性分别达97.1%、97.9%、97.2%,胞外蛋白分别达95.8%9、6.3%、88.6%。不同菌株胞内胞外蛋白产量各不相同。电泳图谱表明,不同菌株间及同一菌株胞内胞外蛋白有差异,但近缘菌株相似。

In this study the extracellular and intracellular proteins were extracted from the fermentation culture of ten strains of the symbiotic bacteria by means of cell disruption, ammonium sulfate precipitation. The protein concentrations were determined. Their oral toxicities against neonatal larvae of Helicoverpa armigera Htibner were tested. The protein components were analyzed with the techniche of Nativepolyacrylamide gel electrophoresis （Native-PAGE） and sodium dodecyl sulphate-polyacrylamide gel electrophoresis （SDS-PAGE）. The results indicated that there were various inhibitory activities of the extracellular proteins and intracellular proteins from seven strains against the larva of H. armigera. Three strains of Xenorhabdus nematophila CB6, All and Bw showed significant weight inhibition. The inhibition percentages reached to 97.1%, 97.9%, 97.2% for intracellular proteins and 95.8%, 96.3%, 88.6% for extracellular proteins respectively. The effect of intracellular proteins seems stronger than that of extracellular ones. In addition, the concentrations of the extracellular and intracellular proteins vary with strains. According to the profiles of Native-PAGE and SDS-PAGE, proteins from different strains showed different bands, but the similar bands appeared from the 3 strains of the same species of Xenorhabdus nematophila.