A method based on syringe pump extrusion with the droplet-forming technique has been developed for micro-encapsulation of crystals and spores from Bacillus thuringiensis within calcium alginate gel microspheres. By utilizing our apparatus, the microspheres with the average size of 20 μm could be obtained through adjusting the weight on plug and pressure of air. SDS-PAGE analysis and plate counting evaluation showed that Bt crystals and spores encapsulated in the mierospheres suffered less destruction resulting from UV irradiation compared with those nonencapsulated. Bioassay a- gainst Plutella xylostella also support the conclusion that encapsulation of crystals and spores within calcium alginate mi-crospheres could decrease the loss of toxicity owing to UV irradiation. The procedure for producing microspheres in this study might be applicable to a wide variety of microencapsulation processes.%采用基于注射挤压器的液滴形成技术制备包裹了苏云金杆菌晶体和芽胞的海藻酸钙凝胶微球.通过调节该装置的活塞重量和空气压力,获得了平均直径为20μm的微球.SDS-PAGE分析与平板菌落涂布实验表明,凝胶微球可有效减少紫外线对苏云金杆菌晶体和芽胞的损伤作用.利用小菜蛾进行的毒力生测发现,凝胶微球可有效防止紫外线引起的晶体和芽胞杀虫毒力的下降.本研究的液滴形成技术也可适用于其它微球包裹过程.
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