论文部分内容阅读
利用海藻酸钠包埋法固定化Acinetobacter johnsonii G2细胞,在非水相介质中生物催化葛根素合成葛根素糖苷,考察了细胞的固定化条件、转化条件以及固定化细胞的操作稳定性.结果表明,最佳固定化条件为:海藻酸钠质量分数为2％,氯化钙质量分数为2％,细胞包埋量的体积分数为50％;最佳转化条件为:温度为40℃,pH为6.47,二甲基亚砜体积分数为20％.在最佳条件下,葛根素在催化体系中质量浓度提高至31.92 g/L,产率达93％,且固定化细胞的重复使用稳定性好.与游离细胞相比,固定化细胞对pH、温度及有机溶剂表现出更强的稳定性,且在非水相介质中催化效率更高.“,”An effective method to produce puerarin glycoside in non-aqueous media by using Acinetobacter johnsonii G2 cells immobilized in sodium alginate is described.The immobilization conditions,biotransformation conditions and operation stability of immobilized cell are investigated.The optimal immobilization conditions are shown as follows:the mass concentrations of both sodium alginate and calcium chloride are 2％ and the volumetric concentration of embeded cells is 50％;The optimal transform conditions are confirmed as that temperature is 40℃,pH is 6.47,and concentration of DMSO is 20％.The yield of puerarin glycosides can achieve 93％ by the immobilization cell using 31.92 g· L-1 puerarin as substrate under optimal conditions.The biosynthesis system remains higher recovery yield during repeated use for 10 reaction batch cycles.The immobilized cell exhibits stronger stability against pH,temperature and organic solvent than free cells,and appears higher catalytic efficiency in non-aqueous media.