利用固定化重组大肠杆菌细胞生产D-塔格糖  

D-tagatose Production Utilizing Immobilized Recombinant Escherichia coli cells

作　　者：付凤根[1] 徐铮[1] 李贵祥[1] 李莎[1] 冯小海[1] 徐虹[1] 

机构地区：[1]南京工业大学食品与轻工学院材料化学工程国家重点实验室,南京210009

出　　处：《中国生物工程杂志》2011年第7期85-90,共6页China Biotechnology

基　　金：高等学校博士点专项科研基金(20103221110006);国家自然科学基金(20906050);江苏省自然科学基金(BK2009357);江苏省高校自然科学研究计划(08KJB530004)资助项目

摘　　要：利用经海藻酸钙包埋的重组大肠杆菌细胞催化D-半乳糖生产D-塔格糖,考察了细胞包埋量、反应条件对固定化细胞催化效率以及对D-塔格糖生产稳定性的影响。确定的最优转化条件为:温度65℃,pH 6.5,添加终浓度为1 mmol/L Mn2+,底物(D-半乳糖)浓度100 g/L,重组大肠杆菌细胞用量40 g/L。固定化小球在0.3%戊二醛溶液中交联30 min可以显著提高其在高温下的机械强度。考察了异构化反应体系中硼酸与底物间的摩尔比对产率的影响。研究结果表明,添加适量的硼酸可以改变原有的化学反应平衡,实现D-塔格糖的高产。利用D-半乳糖为底物在最优的反应条件下催化24 h,固定化细胞对D-半乳糖的转化率最高,可达65.8%,连续转化8批次的平均转化率为60.6%,为工业化生产D-塔格糖奠定了基础。Recombinant E. coli ceils were immobilized with calcium alginate for the isomerization of D- galactose to D-tagatose. The influences of immobilization process and reaction conditions on the catalytic efficiency and D-tagatose production stability of the immobilized cells are investigated. The optimal conditions were as follows： the temperature, pH and mental ion were 65℃ ,6.5 and lmmol/L Mn2^＋, respectively. The optimal substrate （D-galactose） and cell concentrations of 100 g/L and 40 g/L were selected, respectively. Stability of the alginate beads under high temperatures was enhanced after cross-linked by 0.3% glutaraldehyde for 30min. The effect of molar ratio between borate and substrate on isomerization was studied, it was found that borate could change the initial chemical equilibrium of D-galactose isomerization and lead to a high production of D-tagatose. After conversion for 24h, the highest conversion rate for D-tagatose using D-galactose as the substrate reached to 65.8% by immobilized recombinant E. coli cells, and the average conversion rate of eight repeated batch conversions was 60.6%, which laid the foundation for industrial production of D-tagatose.

关 键 词：D-塔格糖 固定化细胞 重组大肠杆菌 硼酸 L-阿拉伯糖异构酶 

分 类 号：Q784[生物学—分子生物学]