苏云金芽胞杆菌聚γ-谷氨酸-明胶微胶囊剂制备及其抗逆性

Formulation and Stress Resistance of Polyγ-glutamate-gelatin Microcapsulation of Bacillus thuringiensis

晶体蛋白是苏云金芽胞杆菌(Bacillus thuringiensis,简称Bt)的主要杀虫成分,其抗热处理能力及抗紫外照射能力差,造成在生产及使用过程中易失活,防效不稳定,残效期短.为改良Bt剂型,探讨了以聚γ-谷氨酸(γ-PGA)–明胶为囊壁材料的复凝聚相分离法制备Bt微胶囊剂的加工工艺,并对制得的Bt微胶囊剂进行了抗热及抗紫外能力分析,比较了Bt成囊前后的杀虫活性和芽胞存活率.结果表明,经紫外(30W)照射4h,Bt微胶囊和Bt原粉对棉铃虫3龄幼虫的相对致死率分别是53.57%和16.60%,芽胞存活率分别是46.63%和6.90%;于80℃处理100min后,对棉铃虫3龄幼虫的相对致死率分别是43.42%和26.11%;于100℃处理15min,Bt微胶囊和Bt原粉的芽胞存活率分别是72.53%和25.50%.Bt微胶囊化可显著提高Bt对热处理及紫外照射的抗逆性.

Crystal protein is the key ingredient for the toxicity of Bacillus thuringiensis （Bt） and it has a characteristic of low resistance to heating treatment and UV irradiation, which would lead to less activity and instability, and reduce the time of residual toxicity. In order to protect its toxicity, a technology of Bt microcapsule by double phase separation-coacervation using poly γ-glutamate（γ-PGA）- gelatin was investigated in this paper. The resistance of the microcapsule to UV irradiation and heating treatment was evaluated by comparing the survival rate of spores and lethality rate to Heliothis armigera of Bt technical and the microcapsule. It was shown that after UV irradiation （30 w） for 4 h, the lethality rates to H. armigera of the microcapsule and Bt technical were 53.57% and 16.60%, and the survival rates of spores of the microcapsule and Bt technical were 46.63% and 6.90%, respectively. It was also illustrated that after heating treatment at 80℃ for 100 min, the lethality rates to H. armigera of microcapsule and Bt technical were 43.42% and 26.11%, respectively. In the case of heating treatment at 100 ℃ for 15 min, the survival rates of the microcapsule and Bt technical were 72.53% and 25.50%, respectively. The microencapsulation technology can effectively increase the resistance ofB. thuringiensis formulation to heating treatment and UV irradiation.