一株对马铃薯瓢虫幼虫有特异活性的苏云金芽孢杆菌新菌株的研究

苏云金芽孢杆菌WZ-9是本室从河北省土壤中分离的对马铃薯瓢虫的幼虫有特异杀虫活性的新菌株，本文对该菌株的形态特征、生长特性、生物活性、基因型和蛋白型等方面进行了研究。结果表明该菌株可产生菱形伴孢晶体，SDS-PAGE检测表达的主要蛋白条带分子量约为130kDa，生长周期是24h，随菌株的生长培养基pH值发生变化；生物活性测定表明该菌对马铃薯瓢虫2龄幼虫72h校正死亡率达100%，LC50为2.95×107细胞/mL；基因型鉴定表明含有cry7基因，获得了一条总长为3781bp基因序列，其中包含了一个3414 bp的开放读码框，其编码的蛋白由1138个氨基酸残基组成，与Cry7Ab2具有99.65%的序列同源性，存在4个氨基酸差异，亲缘关系最近，该蛋白被Bt 杀虫晶体蛋白命名委员会命名为Cry7Ab3( 登录号为BI 1015188) 。

Study about A New Strain WZ-9 of Bacillus thuringiensis with Insecticidal Activity Against Henosepilachna vigintioctomaculata

A high toxicity Bacillus thuringiensis (Bt) strain WZ-9 against larvae of Henosepilachna vigintioctomaculata was isolated from soil of Hebei province. Bipyramidal inclusions could be observed by scanning electron microscopy. SDS-PAGE analysis indicated that the strain produced a 130 kDa protein. Growth cycle of this strain was 24h, and pH of the culture varied with the strain growth. The bioassay results showed that the WZ-9 strain was highly toxic to the 2 instar larvae of H. vigintioctomaculata.. Correct mortality is 100% at 72h, and LC50 is 2.95×107cell/mL. Genotype identify showed this strain had cry7 gene. Sequence analysis showed that the encoding gene contained a ORF of 3414 bps and encoded 1138 amino acids residues. The deduced amino acid sequence is 99.65% identical to that of the reported Cry7Ab2 sequences. By Bt δ-endotoxin nomenclature committee this gene was designated as Cry7Ab3 with accession number BI 1015188 in GenBank database.