【作者】 王爱玲；

【导师】 闫云君；

【作者基本信息】 华中科技大学 ， 微生物学， 2007， 硕士

【摘要】 海藻酸钠明胶微胶囊是起源于海藻酸钠凝胶珠的一种固定化体系,它不仅具有海藻酸钠凝胶珠来源广泛、价格低廉、固定化条件温和、操作简单、生物相容性好以及基质和产物扩散阻力小等诸多优点,而且还能提供更大的固定化空间,更有利于内外物质的扩散,因而是一种有广阔发展前景的新型微胶囊体系。采用海藻酸钠与明胶协同固定化制备微胶囊,考察了海藻酸钠、明胶浓度等因子对微胶囊直径与机械强度的影响,以及牛血清蛋白与葡萄糖向微胶囊的扩散情况,并利用非稳态传递模型计算了这两种物质在微胶囊中的有效扩散系数,结果显示随着海藻酸钠质量浓度的升高,微胶囊的直径与机械强度逐渐增大。制备的最优条件是:海藻酸钠、明胶浓度均为1.25%,CaCl2浓度为10%,滴定速度为180滴/min,浸泡时间为30 min。在此条件下,葡萄糖与牛血清蛋白的有效扩散系数分别为4.63×10-5 cm2/min和1.01×10-7 cm2/min。在此基础上,利用海藻酸钠明胶复合载体固定化荧光假单胞菌脂肪酶LipaseAK,考察了载酶量、颗粒直径等因子对固定化效果的影响,比较了固定化酶和游离酶对温度、pH等条件的稳定性,研究了不同因素对制备固定化荧光假单胞菌脂肪酶的影响以及固定化酶的酶学性质。结果表明,制备固定化脂肪酶的最优条件为:每克载体给酶量为300 IU,选用6号针头(内径为0.5 mm),固定化酶最适温度为55℃,最适pH为8.0,将其在80℃下保温1 h后,仍保留85%的酶活力,而自由酶在同条件下却只有75%左右,固定化酶的pH稳定性与自由酶相比也有一定程度的提高。常见金属离子对固定化酶的活力影响较小。利用自制的固定化荧光假单胞菌脂肪酶催化大豆油制备生物柴油工艺的探索,并系统研究了固定化LipaseAK催化大豆油与甲醇酯交换反应合成生物柴油工艺中各种因子(如酶量、反应温度、甲醇流加方式、醇油比等)的影响。结果表明,通过催化4.585 g大豆油合成生物柴油的最佳反应工艺参数为:固定化酶25%,醇油比4:1,含水量6%,反应温度40℃;在此条件下反应35 h后,甲酯的最高得率可达82%。更多还原

【Abstract】 Sodium alginate-gelatin microcapsule stems from the Ca-alginate bead. It not only possesses the advantages of Ca-alginate bead, such as broad source, inexpensive cost, gentle immobilization conditions, easy operation, good biocompatibility, as well as less resistance to the substrates, but also provides more space for immobilized materials. Therefore, the sodium alginate-gelatin microcapsule is a promising immobilization carrier.During the preparation of sodium alginate-gelatin microcapsule, the effects of concentrations of sodium alginate(SA)and gelatin(GT)on the diameter and compression intensity of the microcapsule were examined, the diffusion coefficients of substrate from the solution into the microcapsule were measured with of glucose and bovine serum albumin fraction(BSA), according to the established mathematical model. The results showed that with the increasing of sodium alginate concentration, the diameter and compression intensity of the microcapsule became bigger. The optimum operation conditions were: the concentration of calcium chloridea 10%, drop rate 180 droplets/min, dipped in calcium chloridea 30min, under which conditions, the effective diffusion parameters of glucose and BSA measured were 4.63×10-5 cm2/min and 1.01×10-7 cm2/min, respectively.By following the above method, lipase from Pseudomonas fluorescens was immobilized. And the effects of immobilization conditions and immobilized enzyme stability against temperature and pH were studied. The results indicated that the optimum immobilized operation conditions were: lipase/sodium alginate ratio 300 IU, the diameter of the pinhead 6(0.5 mm), temperature 55℃and pH 8.0. Metalions and short-chain enathol had an insignificant effect on the immobilized enzyme.Then, the immobilized lipase was used to catalyze the transesterification reaction of soybean oil with methanol to produce biodiesel. The effects of enzyme amount, reaction temperature, adding ways of methanol, molar ratio of substrate on esterification were examined in details. The opitimal conditions of the methanolysis were: enzyme 25% of oil weight, methanol/oil molar ratio 4:1, reacting at 40℃for 35 h, and under which condition, the maximum metyl esters yield was over 82%.更多还原