14株苏云金芽孢杆菌伴胞晶体蛋白对猪蛔虫第3期幼虫的毒性比较

14株苏云金芽孢杆菌经培养提取伴胞晶体蛋白并测定其蛋白含量。感染性蛔虫卵经胃感染小鼠 ,3d后宰杀并从小鼠肝脏内分离蛔虫第 3期幼虫 (L 3)。设置空白对照 ,将不同剂量的 Bt伴胞晶体蛋白与 L 3置于培养孔在 37℃的二氧化碳培养箱中 (含 5 % CO2 )培养 ,间隔 12 h检查幼虫活性 ,计算死亡率、校正死亡率及半数致死量。L D50 随着作用时间的延长而逐渐减小。14株细菌伴胞晶体蛋白对 L 3的毒力差异很大。 0 17株对 L 3的杀虫作用快速而持久、毒力最强 ,其 L D50 是所有 14个菌株中最小的 ,作用 12、2 4和 36 h时分别为 1.135 7、0 .2 32 2和 0 .15 32 g/ L。

Larvicidal Activities of 14 Bacillus thuringiensis Strains Spore-crystal Proteins to Third-stage Larvae of Ascaris Suum

The spore-crystal proteins of 14 Bacillus thuringiensis (Bt) strains were used to determine their larvicidal activities to third-stage larvae (L3) of Ascaris suum. L3 were separated from infected mice 3 d after inoculation. Although the crystal proteins of all the 14 Bt strains were effective to L3 of Ascaris suum, the larvicidal activities were very different. LD_(50) gradually decreased when the test was prolonged. 017 was the most effective strain and acted constantly in this test, and their LD_(50) were 1.135 7, 0.232 2 and 0.153 2 g/L respectively at 12, 24 and 36 h after its crystal proteins added.