The local entomopathogenic bacterium, Bacillus thuringiensis (Bt) was isolated and characterized from 16 soil samples collected from different governorates in Egypt. Among 56 bacterial colonies obtained, only 16 colonies were characterized by traits of Bacillus. All the 16 isolates were toxic to the neonates of the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). Damietta and El-Sharkyia bacterial isolates showed appreciable mortality rates (100 and 96.6%), respectively, which were higher than that caused by the standard isolates of Bt entomocidus (that produce Cry1 C toxin) for which they were selected for further characterization. Scanning electron microscope of Damietta bacterial isolate showed the presence of a bipyramidal crystal protein; consistent with the presence of Cry1 toxin class, however, El-Sharkyia bacterial isolate produced spherical-shaped crystals consistent of Cry2 toxin class. Electrophoretic patterns of different isolates and standards revealed different molecular weight bands, ranged from 195 to 8KDa. Damietta and El-Sharkyia bacterial isolates produced major protein bands with molecular weights of 130 KDa, which was also present in Bt entomocidus. Both isolates also shared protein bands with Bt entomocidus with molecular weights of 80, 70, 65, 51, and 22 KDa. The 16S rRNA sequences of both isolates were submitted to the NCBI Gene Bank database, with accession numbers of LC070660 for Damietta isolate and LC070661 for El-Sharkiya isolate. The existence of different Cry genes in the 2 isolates was studied by PCR, using general primers of 5 Cry genes. Cry1 gene was detected in both isolates; however, Cry 2 gene was detected only in Damietta isolate.

中文翻译：

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来自埃及不同土壤的当地致病菌苏云金芽孢杆菌的分离和鉴定

从埃及不同省份收集的16个土壤样品中分离并鉴定了当地致病细菌苏云金芽孢杆菌（Btillus thuringiensis）（Bt）。在获得的56个细菌菌落中，只有16个菌落具有芽孢杆菌的特征。所有这16种分离株均对棉叶蠕虫（Spodoptera littoralis）（Boisd。）（鳞翅目：夜蛾科）的新生儿有毒。Damietta和El-Sharkyia细菌分离株分别显示出可观的死亡率（100和96.6％），高于由Bt昆虫病原体（产生Cry1 C毒素）的标准分离株引起的死亡率，为此选择了它们进行进一步表征。达米埃塔细菌分离物的扫描电子显微镜显示存在双锥体晶体蛋白。与Cry1毒素类别的存在一致，但是，El-Sharkyia细菌分离物产生了与Cry2毒素类一致的球形晶体。不同分离物和标准品的电泳图谱显示不同的分子量带，范围从195到8KDa。Damietta和El-Sharkyia细菌分离物产生了分子量为130 KDa的主要蛋白带，该蛋白带也存在于Bt昆虫中。两种分离物还与Bt昆虫虫共享蛋白条带，分子量分别为80、70、65、51和22 KDa。两种分离物的16S rRNA序列均已提交至NCBI基因库数据库，Damietta分离物的登录号为LC070660，El-Sharkiya分离物的登录号为LC070661。使用5个Cry基因的通用引物，通过PCR研究了2个分离物中不同Cry基因的存在。在两个分离株中均检测到Cry1基因；然而，