Tyrell D J, Bulla L A, Andrews R E, Kramer K J, Davidson L I, Nordin P
J Bacteriol. 1981 Feb;145(2):1052-62. doi: 10.1128/jb.145.2.1052-1062.1981.
Parasporal crystals of Bacillus thuringiensis subspp. kurstaki, tolworthi, alesti, berliner, and israelensis were compared by electron microscopy, polyacrylamide gel electrophoresis, amino acid analysis, tryptic peptide mapping, immunological analysis, and insecticidal activity. Spore coats also were compared by polyacrylamide gel electrophoresis. B. thuringiensis subsp. israelensis crystals were lethally toxic to mosquito larvae and nontoxic to tobacco hornworm larvae. Conversely, crystals from the other subspecies killed tobacco hornworm larvae but were ineffective against mosquitoes. Crystalline inclusion bodies of all subspecies contained a protoxic subunit that had an apparent molecular weight of approximately 1.34 X 10(5). However, polyacrylamide gel electrophoretic patterns of solubilized crystals revealed a small-molecular-weight component (apparent molecular weight, 26,000) in B. thuringiensis subsp. israelensis that was absent in the other subspecies. Also, differences were noted in amino acid composition and tryptic peptide fingerprints. Crystal proteins were found in spore coats of all subspecies. The results suggest that insecticidal specificity is due to unique polypeptide toxins.
通过电子显微镜、聚丙烯酰胺凝胶电泳、氨基酸分析、胰蛋白酶肽图谱分析、免疫分析和杀虫活性，对苏云金芽孢杆菌库尔斯塔克亚种、托尔沃思亚种、阿莱斯蒂亚种、贝林纳亚种和以色列亚种的伴孢晶体进行了比较。还通过聚丙烯酰胺凝胶电泳对芽孢衣进行了比较。苏云金芽孢杆菌以色列亚种的晶体对蚊虫幼虫具有致命毒性，而对烟草天蛾幼虫无毒。相反，其他亚种的晶体可杀死烟草天蛾幼虫，但对蚊虫无效。所有亚种的晶体包涵体都含有一个原毒素亚基，其表观分子量约为1.34×10⁵。然而，溶解晶体的聚丙烯酰胺凝胶电泳图谱显示，苏云金芽孢杆菌以色列亚种中有一个小分子质量组分（表观分子量为26,000），而其他亚种中没有。此外，在氨基酸组成和胰蛋白酶肽指纹图谱方面也发现了差异。在所有亚种的芽孢衣中都发现了晶体蛋白。结果表明，杀虫特异性是由于独特的多肽毒素所致。
