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Viability and reconstitution of delta-endotoxins from Bacillus thuringiensis var. israelensis extracts after forty years of storage against Aedes aegypti (Diptera: Culicidae)
Egyptian Journal of Biological Pest Control ( IF 2.4 ) Pub Date : 2021-03-03 , DOI: 10.1186/s41938-021-00381-x
David Fernández-Chapa , Hugo Alberto Luna-Olvera , Jesica Ramirez-Villalobos , Guadalupe Rojas-Verde , Katiushka Arévalo-Niño , Luis Jesús Galán-Wong

Bacillus thuringiensis subsp. israelensis (Bti) produces insecticidal endotoxins known as Cry and Cyt. Its efficiency and specificity make it the most widely used substance as a biopesticide for controlling disease from vector insects, such as mosquitoes, responsible for important human diseases such as malaria, filariasis, dengue, and yellow fevers. To date, it is proven difficult to develop a commercial product that has more than 2 years of shelf life, and there is little information on the viability of these commercial proteins under prolonged storage conditions. This study aimed to evaluate biological activity of reconstituted Bti endotoxins after 40 years of storage against the mosquito Aedes aegypti larvae. Five concentrations of Bti extracts were used for bioassays against 3rd and 4th instars of A. aegypti larvae. All reconstituted endotoxins from stored extracts showed a potency increase. The strain HD-500 from extract 3260 was the most effective insecticide (LC50 = 0.0014 mg/l), followed by 3756 (LC50 = 0.0037 mg/l). These strains were particularly notable, increasing their larvicidal potency one hundredfold and one thousandfold, respectively. Protein profiles in polyacrylamide gels revealed a greater presence of Cyt toxins compared to the stored Bti extracts, which maintained their activity at high concentrations. The reconstituted Bti strains presented a great biological activity against A. aegypti larvae, specially extract 3260 (median lethal concentration (LC50) value = 0.0014 mg/l). This considerable larvicidal activity after 40 years under storage was an encouraging signal for the development of future formulation strategies regarding their useful life. The stability of extracts of stored endotoxins produced by Bti decreased significantly, particularly Cyt1A protein, which is responsible for their synergistic activity.

中文翻译:

苏云金芽孢杆菌变种δ-内毒素的活力和重组。以色列伊蚊Aedes aegypti)储存40年后的提取物(双翅目:Cu科)

苏云金芽孢杆菌亚种。以色列(Bti)生产称为Cry和Cyt的杀虫内毒素。它的效率和特异性使其成为控制病媒昆虫(例如蚊子)疾病的生物杀虫剂,是一种最广泛使用的物质,蚊子是导致人类重要疾病(例如疟疾,丝虫病,登革热和黄热病)的原因。迄今为止,已证明难以开发具有超过2年的保存期限的商业产品,并且关于这些商业蛋白质在延长的储存条件下的生存能力的信息很少。这项研究旨在评估重组的Bti内毒素在储存40年后对蚊埃及伊蚊幼虫的生物学活性。使用五种浓度的Bti提取物对埃及伊蚊的第三龄和第四龄幼虫进行生物测定。来自储存的提取物的所有重构的内毒素均显示出效力增加。来自提取物3260的HD-500菌株是最有效的杀虫剂(LC50 = 0.0014 mg / l),其次是3756(LC50 = 0.0037 mg / l)。这些菌株特别引人注目,其杀幼虫能力分别提高了一百倍和一千倍。与储存的Bti提取物相比,聚丙烯酰胺凝胶中的蛋白质谱显示出Cyt毒素的存在更多,后者在高浓度下仍能保持其活性。重组的Bti菌株对埃及伊蚊的幼虫具有很大的生物学活性,特别是提取物3260(中位致死浓度(LC50)值= 0.0014 mg / l)。储存40年后,这种相当大的杀幼虫活性为有关其使用寿命的未来制剂策略的发展提供了令人鼓舞的信号。Bti产生的储存的内毒素提取物的稳定性显着下降,尤其是Cyt1A蛋白,这是它们协同作用的原因。
更新日期:2021-03-04
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