31株苏云金芽孢杆菌杀虫晶体蛋白基因型鉴定及表达产物研究

利用已建立的苏云金芽孢杆菌cry基因的PCRRFLP鉴定体系，鉴定了31株Bt菌株的cry基因类型，并进行了SDSPAGE分析和杀虫生物活性测定。研究表明：25株含cry1基因，表达蛋白130～150kD;其中16株含有对鞘翅目和鳞翅目害虫皆有活性的cry1I基因，其表达蛋白为81kD;15株同时含有cry1和cry2基因(13株表达蛋白约为60kD)；10株含有未知待定基因；6株不含所鉴定的cry基因(其中2株有表达产物)。室内生物测定表明：cry1、cry2基因表达的菌株对鳞翅目害虫具有高杀虫活性，7株对舞毒蛾和膜翅目——杨叶蜂幼虫具有较高杀虫活性；含有cry1Aa\,cry1Ac\,cry2或cry1Ab\,cry1Ac\,cry2基因组合的菌株对棉铃虫幼虫均显示杀虫活性，其中6、12、30号菌株毒力最强。不含上述cry基因的菌株均无杀虫活性。以上结果证明，通过cry基因类型鉴定和表达产物的SDSPAGE分析可以预测菌株的杀虫活性。

IDENTIFICATION OF CRY- TYPE GENES OF 31 BACILLUS THURINGIENSIS ISOLATES AND ANALYSIS OF THEIR EXPRESSION PRODUCT

In this study, cry-type gene of 31 isolates of Bt had been identified using PCR-RFLP identification system, and SDS-PAGE analysis and bioassay had been performed. 25 strains containing cry1 type gene express 130-150 kD protein and 16 of them contain cry1I gene, which codes 80 kD protein and is larvicidal to both lepidopteran and coleopteran species. 15 strains contain both cry1 and cry2 type gene; 10 strains contain unknown cry-type gene; 6 strains don't contain seven identified cry-type gene. Result of bioassay shows that the strains containing both cry1 and cry2 gene have high toxicity to lepidopteran order, 7 of them are strongly insecticidal to Pristiphora beijingensis and Lymantria dispar larvae; the strains containing cry1Ab + 1Ac + 2A or cry1Aa + 1Ac + 2A have high activity to Heliothis armigera; no cry gene, no activity. It is indicated that identification of cry-type gene and its analysis of SDS-PAGE protein can predict insecticidal activity of Bt isolates, and it is no pertinency between cry-type gene and serotype of Bt strain.