非水相体系中海藻酸钠-壳聚糖微胶囊粒径及强度性能

Size and strength of alginate-chitosan microcapsules in nonaqueous system

固定化技术是提高生物催化剂在非水相中活性和稳定性的一种很有工业应用潜力的手段。采用乳化-内部凝胶化与络合反应制备海藻酸钠-壳聚糖(AC)微胶囊作为固定化载体,筛选5种有机溶剂构建了培养基-有机溶剂两相体系,模拟酵母细胞培养条件,将AC微胶囊在培养基-有机溶剂两相体系中振荡48h,5种两相体系对AC微胶囊形态没有明显影响;在培养基-癸二酸二丁酯两相体系中,当壳聚糖分子量在40000～100000、成膜反应时间在2～5min范围内变化时,分子量小(40000)和成膜时间长(5min)的AC微胶囊粒径稳定,破碎率较低、机械强度较大,适于用作进一步非水相细胞催化的固定化载体。两相体系中AC微囊化酵母细胞活性保持良好,能实现生物转化生产。

Immobilization technology is of potential in industrial application for improving activity and stability of biocatalyst in nonaqueous systems.Alginate-chitosan（AC）microcapsules as immobilization carrier were prepared by emulsification-internal gelation and complexation reaction,and five solvents were selected to form culture medium-solvent two phase systems.At simulating yeast culture condition,AC microcapsules were put into the two phase systems and oscillated for 48 h.The morphology of AC microcapsules had no change for different two phase systems.For culture medium-dibutyl sebacate system,molecular weight of chitosan and formation time of microcapsule membrane were varied in a range of 40000—100000 and of 2—5 min,respectively,AC microcapsules with stable size,low broken rate and high mechanical strength were produced at conditions of low Mw（40000）chitosan and long formation time（5 min）.These results showed that AC microcapsules prepared with above condition could be applied as immobilization carrier of biocatalyst.Moreover,yeast cells with biotransformation ability was used as a model of biocatalyst and entrapped in AC microcapsules.The growth of yeast cells entrapped in AC microcapsules to produce 2-phenylethanol was investigated in the culture medium-solvent two phase systems.The results showed that entrapped cells still keep its activity and can normal grow,which means that two phase systems have no adverse effect on it.Therefore,the immobilized yeast cells are of high biotransformation ability in the culture medium-solvent two phase systems with substrate concentration of 8—16 g·L-1.