用海藻酸钠对Amycolatopsis sp.ST2710细胞进行固定化处理。以固定化细胞的机械强度以及分段发酵无锡他汀的转化率为指标,考察了海藻酸钠浓度、CaCl2浓度、固定化时间和包埋菌体量对固定化细胞分段发酵无锡他汀的影响,得到最佳的固定化条件为:海藻酸钠浓度20 g/L、CaCl2浓度10 g/L、固定化时间1 h、包埋菌体量2 mL菌悬液/10 mL凝胶。对固定化细胞分段发酵无锡他汀的特点进行了研究,结果显示:Amycolatopsissp.ST2710经过固定化处理后,大幅度提升了其对底物洛伐他汀的耐受性,显著降低了对发酵培养基中的淀粉需求量,可重复利用。当发酵两阶段pH分别为7.5和5.5、发酵时间分别为48 h和10 h、洛伐他汀添加量3 g/L、转化培养基中淀粉浓度15 g/L时,中间产物Ⅰ对洛伐他汀转化率为64%,无锡他汀对中间产物Ⅰ的转化率为75%。连续发酵5批后,产物转化率仍能维持较高的水平。

In this paper,the whole cell of Amycolatopsis sp.ST2710 was immobilized by alginate sodium.In order to obtain the optimal immobilization conditions for mechanical strength and conversion,some factors including alginate sodium concentration,calcium chloride concentration,immobilization time,and strain embedded volume were investigated.The optimal condition was: alginate sodium 20 g/L,calcium chloride 10 g/L,immobilization time 1 h,and 2 mL strain embedded in 10 mL beans.After immobilizing,the tolerance to lovastatin concentration was promoted greatly,starch concentration in transformation medium was obviously reduced,and the immobilization cells could be reused.Under the condition of 3 g/L lovastatin and 15 g/L starch in the transformation medium,the conversion rate reached 64% with pH 7.5 for 48 h in the first stage,and the conversion rate reached 75% with pH 5.5 for 10 h in the second stage.After 5 batches fermentation,the conversion rate still maintains at high levels.