微米级单分散微胶囊菌剂的可控制备及其菌体释放与存活调控机制研究

In view of serious soil salinization of Xinjiang, viable bacteria of free microbial agents are short survival time, poor persistent effect, and low stability, as well as the current microcapsule formulation is not fit for the application modes as drip irrigation and seed coating modes. So, alleviating salt stress and promoting growth bacteria screened autonomously were used as research object, the present study deals with the preparation of micron-scale monodispersed microcapsule bacterial agents, and the regulating mechanisms of its cell controlled release and survival. By revealing the correlation between microcapsule preparation methods, the process parameters and microstructure, performance of microcapsule, which can provide a theoretical basis for obtaining controllable preparation of micron-scale monodispersed microcapsule bacterial agent. By illustrating the effect of the microstructure and environmental factors on slow controlled mass transfer behavior and survivability of microencapsulated bacteria, the release kinetics model and survival stability model were constructed and the relationship between preparation methods, microstructure, cell release and survival of microcapsules bacterial agents could be confirmed. Through the in-depth study the growth metabolism, colonization and interaction with crop of microencapsulated bacteria could be constructed the regulatory mechanisms of cell release and survival characteristics of microcapsule microbial agents for better meeting the actual need of viable bacteria colonization amount during the growing process of crop. The research provides new ideas and methods for widening microbial agent’s application range and effect on agriculture, food and pharmaceutical industries. Thus, the investigation has significant research value and potential application promotion value.

针对新疆土壤盐渍化严重、游离生物菌剂活菌存活期短、持效性差、稳定性低，以及现有菌体微胶囊剂型不适于滴灌及种子包衣应用方式等问题，课题以自主筛选的解盐促生菌为研究对象，开展微米级单分散微胶囊菌剂制备及其菌体释放与存活调控机制研究，通过揭示菌体微胶囊的制备方法及过程参数与微胶囊微结构及性能的相关性，为获得微米级单分散微胶囊菌剂的可控制备提供理论基础；通过阐明微胶囊的微结构及环境因子对微胶囊化菌体的传质释放行为及存活性的影响规律，构建微胶囊化菌体释放动力学模型和存活稳定模型，确立微胶囊菌剂的制备方法-微结构-菌体释放与存活效应的关系；深入研究微胶囊化菌体的生长代谢、定殖及与作物互作效应，建立微胶囊菌剂的菌体释放与存活特性的调控机制，更好满足作物生长过程中对活菌定殖量的实际需求。该研究为拓宽微生物制剂在农业、食品及医药等行业的应用范围及效果提供新思路和新方法，具有重要的理论研究价值和应用推广价值。

开展了微米级单分散微胶囊菌剂的可控制备及其菌体释放与存活调控机制研究，主要体现如下：.第一、获得了菌株微囊化制备的关键技术参数：锐孔-凝固浴法复合壁材最优配比为海藻酸钠-膨润土-淀粉：1.5%-4%-3%，胶囊粒径在1000 μm左右；而内源乳化法微胶囊的最佳制备条件为海藻酸钠-明胶浓度2%和1.5%，菌胶比1:3，碳酸钙浓度2.5%；外源乳化法采用1.5%海藻酸钠和0.5%膨润土复合，菌胶比1:2，在转速1800 rpm，获得较好的结构特征和较高的包埋性能微胶囊。揭示了其对菌体微胶囊的微结构及性能的影响规律以及微结构与性能间的制-构关系。.第二、表明海藻酸钠-明胶微胶囊可以在35天内实现较高的释放量，25℃贮藏120天保持较好的菌体活性；海藻酸钠-膨润土微胶囊可以提高菌体存活量。微胶囊化对菌体产IAA，氨氮和溶磷的能力等促生特性基本没有影响，同时菌体在微胶囊中前3天累积释放较快，释放动力学两个阶段均符合Ritger-Peppas模型，揭示了菌体微胶囊的微结构及物理化学性能对微胶囊内菌体的释放特性与存活稳定性的影响规律。.第三、揭示壁材对微胶囊膜通透性与微胶囊表面孔径有关，同一壁材相同的储存条件下，随着标记物分子量增大膜扩散通透系数（P）逐渐减小。P值随着壁材中海藻酸钠或膨润土浓度增加而减小，随着储存温度，pH和盐浓度增加而增大。表明微胶囊释放过程大致分为前期的聚合物溶胀，恒定速率释放以及逐渐衰减的释放阶段。恒定释放阶段主要受扩散作用的影响，应用菲克扩散第二定律，分析菌体释放过程及释放机制。.第四、通过分析微胶囊菌剂中菌体从释放并成功定殖到植株根部促进生长的过程，构建了微胶囊化菌体缓控释放动力学模型；微胶囊化的菌剂对棉花的根长、鲜重及干重都表现出良好的促生作用；通过调节植株对矿物元素的吸收来缓解盐胁迫，提高植株耐盐能力，阐述了微胶囊化微生物菌肥根际定殖存活特性和解盐促生机制。.该项目的研究结果已发表SCI论文12篇，获得各类奖励21项，参加国内外学术会议8次，培养硕士研究生7人，其中毕业4名。