Song Lingli, Gao Meiying, Dai Shunying, Wu Yan, Yi Dan, Li Rongsen
Wuhan Institute of Virology, Chinese Academy of Sciences, Xiaohongshan 44, Wuhan City, Hubei Province 430071, PR China.
J Invertebr Pathol. 2008 Jun;98(2):169-76. doi: 10.1016/j.jip.2008.02.006. Epub 2008 Feb 20.
Bacillus thuringiensis (Bt) has played an important role in biocontrol of pests. However, insecticidal activity of B. thuringiensis against locusts has been rarely reported. Bt strain BTH-13 exhibiting specific activity to locusts was isolated from a soil sample in China and characterized. Its bipyramidal parasporal crystal is mainly composed of a protein of 129kDa, and produces a mature toxin of 64kDa after activation. The pattern of total DNA from BTH-13 showed a large and three small plasmid bands. Known delta-endotoxin genes, cry1Aa, cry1Ab, cry1Ac, cry1C, cry3, cry4 and cry7Aa were not found from strain BTH-13 by PCR amplification. The sequence analysis of a DNA fragment produced by PCR amplification with degenerate cry-selective primers revealed that the fragment encoded a delta-endotoxin segment, which exhibited some similarity to several Cry proteins (41% of the highest similarity to Cry7Ba1). Toxicity tests were performed against Locusta migratoria manilensis, and the results demonstrated that trypsin-treated sporulated cultures and crystal proteins had high toxicity to larval and adult locusts. Cry toxin of BTH-13 was detected on the midguts of treated locusts using immunofluorescent technology, which confirmed the site of action of the crystal proteins in their toxicity for locusts.
苏云金芽孢杆菌（Bt）在害虫生物防治中发挥了重要作用。然而，苏云金芽孢杆菌对蝗虫的杀虫活性鲜有报道。从中国的一份土壤样本中分离出了对蝗虫具有特异性活性的Bt菌株BTH - 13并对其进行了表征。其双锥形伴孢晶体主要由一种129kDa的蛋白质组成，激活后产生一种64kDa的成熟毒素。BTH - 13的总DNA图谱显示有一条大的和三条小的质粒带。通过PCR扩增，在菌株BTH - 13中未发现已知的δ-内毒素基因cry1Aa、cry1Ab、cry1Ac、cry1C、cry3、cry4和cry7Aa。用简并cry选择性引物进行PCR扩增产生的一个DNA片段的序列分析表明，该片段编码一个δ-内毒素片段，其与几种Cry蛋白表现出一定的相似性（与Cry7Ba1的最高相似性为41%）。对东亚飞蝗进行了毒性试验，结果表明，经胰蛋白酶处理的芽孢化培养物和晶体蛋白对幼虫和成虫蝗虫具有高毒性。利用免疫荧光技术在处理过的蝗虫中肠中检测到了BTH - 13的Cry毒素，这证实了晶体蛋白对蝗虫毒性的作用位点。
