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首页> 外文期刊>African Journal of Biotechnology >Isolation and characterization of native Bacillus thuringiensis isolates from Saudi Arabia
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Isolation and characterization of native Bacillus thuringiensis isolates from Saudi Arabia

机译：沙特阿拉伯苏云金芽孢杆菌天然菌株的分离和鉴定

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A total of 500 soil samples were collected from different localities across the kingdom to isolate native?Bacillus thuringiensis?(Bt) strains. Sodium acetate- (0.25 M) -selection heat-pasteurization, and 50% ethanol treatment methods were used for Bt isolation. Phenotypic characterization and identification of recovered Bt isolates was accomplished on the basis of morphological characteristics of colonies, parasporal crystal, and spores, as well as hemolytic activity, motility, susceptibility to antibiotics, and carbohydrate utilization (API 50CH system). Analysis of 16S rRNA gene was performed to further confirm Bt species identity and differentiate the spore-forming bacilli. Bioassay tests were conducted on larvae of?Aedes caspius?and?Culex pipiens. Based on results, a total of 64 Bt isolates were recovered and the overall Bt index corresponding to the whole sampling areas was 0.25. Most of Bt isolates showed spherical crystals (56%), while, irregular, bipyramidal, and attached crystal to the spores constituted 14, 10 and 6% respectively. The most common biochemical type (31%) was as that of the reference Bt subsp.?kurstaki?(Btk).?The 16S rRNA gene analysis, using the universal primer, provided an efficient identification of Bt isolates and their discrimination from the closely related?Bacillus cereus, as well as from other spore forming bacilli. Bioassay showed that only one Bt isolate exhibited anti-diptera activity similar to Btk strain while most of the native Bt isolates exhibited weak (<30% mortality) or non insecticidal activity. However, results of motility, hemolytic activity, antibiotic-susceptibility patterns, and crystal shape, seem to suggest that many of our Bt isolates may exhibit parasporins activity.
机译：从沙特阿拉伯不同地方收集了总共500个土壤样品，以分离出苏云金芽孢杆菌（Bt）。 Bt分离使用乙酸钠（0.25 M）选择热巴氏灭菌和50％乙醇处理方法。根据菌落，孢子旁晶体和孢子的形态特征，以及溶血活性，运动性，对抗生素的敏感性和碳水化合物利用（API 50CH系统），对回收的Bt分离物进行表型鉴定和鉴定。进行16S rRNA基因分析以进一步确认Bt物种身份并区分形成孢子的细菌。对“伊蚊”和“淡色库蚊”的幼虫进行了生物测定测试。根据结果​​，总共回收了64个Bt分离株，对应于整个采样区域的总Bt指数为0.25。大多数Bt分离物显示出球形晶体（56％），而不规则，双锥体和附着在孢子上的晶体分别占14、10和6％。最常见的生化类型是参考Bt亚种kurstaki Btk（31％）。使用通用引物进行的16S rRNA基因分析可有效鉴定Bt分离株，并从严密的分离中鉴别它们。相关的蜡状芽孢杆菌，以及其他孢子形成杆菌。生物测定法显示，只有一种Bt分离物表现出与Btk菌株相似的抗双翅目活性，而大多数天然Bt分离物表现出较弱的（<30％死亡率）或非杀虫活性。然而，运动性，溶血活性，抗生素敏感性模式和晶体形状的结果似乎表明，我们的许多Bt分离株都可能具有副孢菌素活性。

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