Abstract: The conditions of extraction and parification of the larvicidal toxins of Bacillus sphaericus C_3-41 and Bs_-10 and the toxin characteristics were reported in this paper. Preliminary extract of toxic protein was obtained by freezing and thawing the spore-arystal complex. Then the larvicidal toxins were purified by Sephadex G-75 and DEAE-52 chromatography. When subjected to PAGE under denaturing conditions, the toxic proteins of strains C_3-41 and Bs_-10 migrated in positions corresponding to 40 kilodaltons(kDa). The LC₅₀ values of the toxins of C_3-41 and Bs_-10 against the third instar larvae of Culex quinquefasciatus were 26.99 and 37.92ng/ml respectively. The toxic proteins from strain C_3-41 and Bs_-10 were not stable by heat-treatment for 20 minutes at 50-80℃ and by treatment with 0.05-0.2N NaOH for 24 hrs. The toxicity of the larvicidal toxins can be destroyed by pronase but not by trypsin. The experimental results showed that both hydrolysazed toxins by acid were composed of sixteen kinds of amino acid and the toxic composition of C_3-41 and Bs_-10 were similar to those of B.s.2297 and Bacillus thuringiensis subspecies israelensis.

摘要： 本文以球形芽孢杆菌C_3-41、Bs_-10和2362菌株为材料,研究了从冻融芽孢中提取和纯化杀蚊毒素蛋白的条件,并对其毒蛋白的分子量、杀蚊活性、稳定性及氨基酸组成进行了检测,用0.05N NaOH溶解得到的毒蛋白粗制品,经SephadexG-75和DEAE-52两次柱层析,可得到纯化的毒蛋白。C_3-41)和Bs_-10的毒素蛋白的分子量均为40KDa,对Ⅲ龄致倦库蚊幼虫感染24小时的LC₅₀值分别为26.99ng/ml和37.92ng/ml,该毒蛋白对热处理(50～80℃,20分钟)和0.05～0.2N NaOH处理(24小时)具有不稳定性。对胰蛋白酶具有机性,但链霉蛋白酶可使其完全丧失杀蚊活性,在pH9～10中保存48小时对其毒性没有影响。C_3-41和Bs_-10的毒蛋白由16种氨基酸组成。C_3-41毒蛋白的氨基酸组成与B.s.2297和B.t.i的毒素相同,但与Bs_-10毒素略有差异。

关键词: 球形芽孢杆菌C_3-41菌株, 致倦库蚊, 毒素蛋白, 氨基酸分析