title: Biopolymer microencapsulations of Bacillus thuringiensis crystal preparations for increased stability and resistance to environmental stress.
abstract: 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.
authors.affiliation: School of Life Science, Beijing Institute of Technology, Beijing, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: He
authors.affiliation: School of Life Science, Beijing Institute of Technology, Beijing, China.
authors.forename: Zhongqin
authors.initials: Z
authors.lastname: Sun
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China. klhe@ippcaas.cn.
authors.forename: Kanglai
authors.initials: K
authors.lastname: He
authors.affiliation: School of Life Science, Beijing Institute of Technology, Beijing, China. guosy@bit.edu.cn.
authors.forename: Shuyuan
authors.initials: S
authors.lastname: Guo
mesh_terms: D000464:Alginates / Q000737:chemistry; D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D061046:Biological Control Agents / Q000737:chemistry; D001704:Biopolymers / Q000737:chemistry; D002214:Capsules / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry; D003460:Crystallization; D003890:Desiccation; D004731:Endotoxins; D020723:Glucuronic Acid / Q000737:chemistry; D006460:Hemolysin Proteins; D006603:Hexuronic Acids / Q000737:chemistry; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007814:Larva; D009036:Moths; D010572:Pest Control, Biological / Q000379:methods; D013312:Stress, Physiological; D014466:Ultraviolet Rays
chemical_list: D000464:Alginates; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D061046:Biological Control Agents; D001704:Biopolymers; D002214:Capsules; D004731:Endotoxins; D006460:Hemolysin Proteins; D006603:Hexuronic Acids; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D020723:Glucuronic Acid; D048271:Chitosan
keywords: Bacillus thuringiensis; Bioinsecticide; Cry1Ac; Microcapsules; Parasporal crystals