苏云金杆菌（Bt）微胶囊剂的研制

【作者】 朱丽云；

【导师】 孙培龙； 张立钦；

【作者基本信息】 浙江工业大学 ， 农药学， 2002， 硕士

【摘要】 由于苏云金杆菌(Bacillus thuringiensis简称Bt)杀虫有效成份为生物活体，抗紫外能力较差，因此在野外防治过程中易受外界不良环境的影响而失活。为保证其贮存稳定性并在田间充分发挥作用，选择合适的剂型是很重要的。微胶囊剂是目前最好的控制释放技术之一，能大大增强微生物农药的抗逆性，解决微生物农药贮藏稳定性和田间使用的持效性问题。本研究旨在从生产上使用的4种主要Bt菌株中选择一种优良菌株，对其进行微胶囊剂型的研究。现取得结果如下： 1．菌株的确定和培养：对4种苏云金杆菌的形状特征及与制备微胶囊相关的抗逆性性能进行了研究，其中从扬州农科所提供的菌粉中分离得到的苏云金杆菌(记为Bt1)为制备微胶囊的最佳菌株。Bt1对紫外照射抵抗力较差，照射2小时，活性从100％下降到60％。 2．微胶囊加工工艺的研究：比较了单凝聚相法、复凝聚相法及凝固浴法等方法制备Bt1微胶囊剂，结果复凝聚相法制备的微胶囊中，不同壁材所得的微胶囊化包囊率、平均粒径、贮存稳定性等指标均高于其他方法。分别以①明胶-阿拉伯胶、②明胶-果胶、③明胶-海藻胶、④明胶-羧甲基纤维素钠为壁材的复凝聚相法制备微胶囊剂，其中以①、②为壁材的微胶囊剂包囊率、平均粒径、贮存稳定性等指标明显优于其他方法。 3．微胶囊剂的毒力测定：将菜叶浸泡于各种微胶囊剂悬浮液中3分钟，自然晾干，经紫外照射2hr后用来喂食小菜蛾，结果发现对小菜蛾的毒力以明胶-阿拉伯胶壁、明胶-果胶壁的微胶囊剂最高，其校正死亡率分别为66.7％、60％。对家蚕的毒力测定结果类似于对小菜蛾的结果，其校正死亡率分别为60％、50％。 以包囊率、平均粒径、贮存稳定性、毒力测定为指标，经综合评价确定明胶-阿拉伯胶、明胶-果胶为壁材的复凝聚相法工艺为制备Bt1微胶囊剂的最佳制备工艺，其工艺配方如下： ①明胶-阿拉伯胶为壁材的最佳工艺配方：1％菌液浓度，3％明胶，3％阿拉伯胶，体系温度50℃，搅拌转速为200r/min。其包囊率为80.1％，平均粒径为53.6μm。 ②明胶-果胶为壁材的最佳工艺配方：5％菌液浓度，5％明胶，2％果胶，体系温度40℃，搅拌转速为300r／min。其包囊率为83.2％，平均粒径为55.5μm。更多还原

【Abstract】 Due to Bacillus thuringiensis biologic activity and their poor power in preventing from ultraviolet, Bacillus thuringiensis is prone to lost activity and to represent instability because of bad condition during the course of prevention and cure in the field. So, it is important to select appropriate preparation to assure the stability in deposited and to exert the full measure of its effect in the field. Microcapsule preparation was known as one of the best controlled release preparation, It was shown that the resistance to harmful conditions is strengthened, it would last the effect when it used in the field and could enhance its storing stability. Microcapsulation of the excellent strain of Bacillus thuringiensis that selected from 4 strains of Bacillus thuringiensis in used widely was studied in this paper. The conclusions have been obtained as follows:1. Selecting and culturing Bacillus thuringiensis stain. The appearance, characteristic and resistance to harmful conditions related to microcapsulation was studied on the present four stains of Bacillus thuringiensis, The excellent Bacillus thuringiensis strain(Btl) is separated from bacterium preparation of yangzhou. The resistant to ultraviolet irradiation is poor and its activity come down from 100% to 60% after irradiating 2 hours.2. Microcapsulation process. The microcapsulation methods of Bacillus thuringiensis, such as phase separation-coacervation, double phase separation-coacervation and freeze immersion were studied in this paper, the microcapsules preparation which made by the double phase separation-coacervation method was better than the other preparation in terms of their inwrap rate, average diameter, storing stability. The microcapsulation materials of double phase separation-coacervation, such as Gelatin glue-Acacia glue, Gelatin glue-Pectin glue, Gelatin glue-Alginic glue, Gelatin glue-Sodium Carboxymethyl Cellulose glue were also studied. The above-mentioned parameter of two former materials were better than other materials evidently.3. Tested poisonous power of microcapsules. The small cabbage moths were fed treated vegetables that immersed 3min microcapsules suspension and dried by airing, then lighted up by ultraviolet 2 hours. The poisonous power to small cabbage moths treated by the Gelatin glue -Acacia glue microcapsule and Gelatin glue-Pectin glue microcapsule were higher. Accordingly, their rectified death rate to small cabbage moth was 66.7% and 60% separately. The similar results gained in silkworm’s testing of poisonous power and the rectified death rate of the Gelatinglue -Acacia glue microcapsule and Gelatin glue-Pectin glue microcapsule to silkworm’s rectified was 60% and 50% separately.In terms of inwrap rate, average diameter, storing stability, virulence test of microcapsules preparation, confirmed that the double phase separation-coacervation method with the Gelatin glue-Acacia glue or the Gelatin glue-Pectin glue was the better the preparation method.The best technique conditions of the microcapsules preparation with the Gelatin glue-Acacia glue were: the concentration of Bacillus 1%, the concentration of Gelatin glue and Acacia glue 3% separately, the system temperature 50 and the rotate speed 200r/min. Its inwrap rate was 80.1%, and average diameter was 53.6 n m.The best technique conditions of the microcapsules preparation with the Gelatin glue-Pectin glue were: the concentration of Bacillus 5%, the concentration of Gelatin glue 5, Pectin glue 3%, the system temperature 40 and the rotate speed 300r/min. Its inwrap rate was 83.2%, and average diameter was 55.5 u m.更多还原