含cry8型基因苏云金芽孢杆菌的分离和鉴定

Isolation and Identification of Bacillus thuringiensis Strains Containing cry8 Genes

为发掘对蛴螬有防治作用的苏云金芽孢杆菌及其cry基因,在河北省各县市共采集土壤样品254份,采用温度筛选法分离出Bt菌株42株,经PCR-RFLP方法鉴定,其中10株含有cry8型基因。这些菌株有如下特点：同一菌株含1种或多种质粒;PCR-RFLP鉴定证明有多种cry8基因存在,多数菌株中含2种cry8基因,如cry8E和cry8F常共存于同一菌株中;Cry8杀虫晶体蛋白分子量约为130-140 k Da,晶体形态均为球形。这10株菌采样地点分布于保定、衡水、邯郸、廊坊、唐山和邢台等地,植被类型多样化,说明cry8型Bt菌株在河北省分布广泛,可为蛴螬类害虫的防治提供丰富的Bt资源。

It is very important to explore the source of both Bacillus thuringiensis and its cry gene for pest control. In this study,using a method that the soil suspensions were incubated at 80 ℃ for 20 min in a water bath,forty two Bt strains were isolated from 254 soil samples which were collected from different counties of Hebei province.Ten strains of them are identified that they contain the different plasmids harboring cry8 gene. PCR-RFLP analysis revealed that： One strain may have 1 or more kinds of plasmids; PCR-RFLP results showed that there were multiple cry8-type genes in the strains and one strain usually contained two subtypes of cry8 gene,for example,cry8 E and cry8 F which were often coexist in the same strain; The Cry8-type insecticidal crystal proteins has a molecular weight around 130- 140 k Da with spherical parasporal crystals in shape. The soil samples containing the cry8-type Bt strains were collected from Baoding,Hengshui,Handan,Langfang,Tangshan and Xingtai areas of Hebei province with various vegetation. These results implied that the cry8-type Bt strains extensively distribute in Hebei province and may provide abundant resources of Bt with insecticidal activity against the cockchafer pests.