In this study, potential of the native Bacillus thuringiensis Berliner was investigated against the root knot nematode, Meloidogyne incognita (Kofoid and White) under laboratory and greenhouse conditions. Fourteen out of 50 Bt isolates obtained from root zone of vegetable crops of north western zone of Tamil Nadu, India, were found to be encoded with nematicidal cry genes, confirmed by gene-specific PCR. Nine different Cry protein profiles were obtained from native Bt. Spore-crystal mixtures of 6 isolates out of 14 (at 0.5%) showed 100% inhibition to J2 juveniles emergence from egg masses of M. incognita within 72 h of treatment. Analysis by SEM revealed that fluffy egg masses were observed in untreated samples due to hatching, whereas egg masses were covered by gelatinous matrix, when treated with spore-crystal mixture of nematicidal Bt. Two (BC and BD) of the 6 isolates were selected based on their highest nematicidal activity against J2 of M. incognita with LC50 values of 0.12 and 0.23 μg/ml of protein. The spore-crystal mixtures of isolates BC and BD when applied to tomato plants under greenhouse conditions exhibited the enhanced biocontrol potential by suppressing number of egg masses, reduction of female population and decreased root gall index, when compared to control and chemical treatments.

中文翻译：

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苏云金芽胞杆菌对根结线虫Meloidogyne incognita（Kofoid和White）的杀线虫活性

在这项研究中，在实验室和温室条件下，研究了苏云金芽孢杆菌柏林菌对根结线虫根结线虫（Meloidogyne incognita）（Kofoid和White）的潜力。经基因特异性PCR证实，从印度泰米尔纳德邦西北部蔬菜作物根部获得的50个Bt分离株中，有14个被编码为杀线虫基因。从天然Bt获得了九种不同的Cry蛋白谱。14个分离物中的6个分离物的孢子-晶体混合物（0.5％）显示在处理72小时内100％抑制了隐孢子虫卵团中J2幼虫的出苗。SEM分析表明，在未处理的样品中由于孵化而观察到蓬松的卵块，而当用杀线虫Bt的孢子-晶体混合物处理时，卵块被胶状基质覆盖。根据六种分离物对线虫J2的最高杀线虫活性，选择LC50为0.12和0.23μg/ ml的蛋白质中的两种（BC和BD）。与对照和化学处理相比，当在温室条件下将分离株BC和BD的孢子-结晶混合物施用于番茄植物时，通过抑制卵量，减少雌性种群和降低根胆指数，它们具有更高的生物防治潜力。