School of Life Science, Beijing Institute of Technology, Beijing, China.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Appl Microbiol Biotechnol. 2017 Apr;101(7):2779-2789. doi: 10.1007/s00253-016-8070-y. Epub 2017 Jan 3.
Parasporal crystals synthesized by Bacillus thuringiensis (Bt) have been widely used as microbial pesticides because of their toxicity to the larval stages of specific insects. However, parasporal crystals can be damaged by environmental stresses, such as high temperature, ultraviolet radiation, and desiccation. To reduce environmental susceptibility of parasporal crystals and extend the duration of their activity, we developed a new type of protection by making microcapsules of crystals (MCs). The microcapsules were self-assembled by alternate deposition (layer by layer) of low-cost chitosan and sodium alginate (or sodium carboxymethyl cellulose) on the crystal surface. Crystal toxins (Cry1Ac) were released from microcapsules at pH values above 9.0. Bioassay results demonstrated that microencapsulated preparations had larvicidal toxicity equivalent to the non-encapsulated form. Microencapsuled crystals were protected from environmental stresses such as high temperature and desiccation. The results indicate that microcapsule protection can enhance the efficacy of Bt in pest control, especially to Lepidoptera larvae that have a alkaline midgut.
苏云金芽孢杆菌（Bt）合成的伴孢晶体因其对特定昆虫幼虫阶段的毒性而被广泛用作微生物农药。然而，伴孢晶体可能会受到环境压力的破坏，如高温、紫外线辐射和干燥。为了降低伴孢晶体对环境的敏感性并延长其活性持续时间，我们通过制作晶体的微胶囊（MCs）开发了一种新的保护方法。微胶囊通过在晶体表面交替沉积（层层）低成本壳聚糖和海藻酸钠（或羧甲基纤维素钠）自组装而成。晶体毒素（Cry1Ac）在 pH 值高于 9.0 时从微胶囊中释放。生物测定结果表明，微囊化制剂具有与非囊化形式相当的杀虫毒性。微囊化晶体受到高温和干燥等环境压力的保护。结果表明，微胶囊保护可以提高 Bt 在害虫防治中的功效，特别是对具有碱性中肠的鳞翅目幼虫。
