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采用固定化Pseudomonas putida CGMCC3830转化3-氰基吡啶制备烟酸。选择海藻酸钠作为包埋材料进行固定化,考察固定化细胞的制备条件、转化条件以及批次稳定性。结果表明,优化的固定化条件为:海藻酸钠2 g/dL,氯化钙0.4 g/dL,固化时间6 h;最适转化条件为:温度35℃,pH 7.0,底物浓度100 mmol/L。批次转化实验结果显示,当底物浓度为100 mmol/L时,固定化细胞重复使用10次,酶活仍保留59.1%,产物烟酸的得率为91.8 g/g细胞干重,而游离细胞的使用3次后,酶活下降至45.6%。
Nicotinic acid was prepared by converting 3-cyanopyridine into immobilized Pseudomonas putida CGMCC3830. Sodium alginate was chosen as the immobilized material, and the preparation conditions, transformation conditions and batch stability of immobilized cells were investigated. The results showed that the optimal immobilization conditions were as follows: sodium alginate 2 g / dL, calcium chloride 0.4 g / dL, and curing time 6 h. The optimum conditions were: temperature 35 ℃, pH 7.0, substrate concentration 100 mmol / L. Batch transformation experiments showed that when the substrate concentration was 100 mmol / L, the immobilized cells were reused 10 times, the enzyme activity still retained 59.1%, the yield of niacin was 91.8 g / g dry cell weight, while the free After three cell uses, enzyme activity dropped to 45.6%.