Biodegradable Calcium Alginate Microspheres as Protection System for Crystals and Spores from Bacillus thuringiensis against UV Degradation

A method based on syringe pump extrusion with the droplet-forming technique has been developed for microencapsulation 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 microspheres suffered less destruction resulting from UV irradiation compared with those nonencapsulated.Bioassay against Plutella xylostella also support the conclusion that encapsulation of crystals and spores within calcium alginate microspheres 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.