利用改性载体固定化大肠杆菌产琥珀酸

采用聚乙烯亚胺（PEI）和戊二醛（GA）对棉纤维进行化学修饰，考察了载体改性后的性能和对固定化大肠杆菌产丁二酸的影响。改性后的载体菌体负载量提高了63.3%。培养基中葡萄糖浓度为43 g/L，添加改性棉纤维120g/L，以MgCO3为缓冲盐，进行批式发酵，丁二酸浓度达到29.6 g/L，比未改性棉纤维提高了11.3%；丁二酸收率达到70.5%，比改性前提高了7.5%；丁二酸生产速率达到0.66 g/(L?h), 比改性前提高了37.5% 。对该材料固载的细胞进行7次重复批式发酵，丁二酸产量、转化率和产率没有下降趋势，具有一定的重复稳定性。

Succinic acid production with immobilized cells of Escherichia coli on modified carrier

Immobilization of Escherichia coli on cotton fiber modified by polyethylenimine coating and glutaraldehyde crossing-linking for succinic acid production was investigated. Compared with unmodified cotton fiber, static cell adhesion increased by 63.3% after the carrier was modified by PEI and GA. When 43 g/L glucose was put in fermentation medium, 120 g/L PEI-GA cotton fiber was added, and MgCO3 was used as neutralizer in batch fermentation, concentration of scuccinic acid was 29.6 g/L, productivity was 0.66 g/(L?h)and yield was 70.5%, increased by 11.3%, 37.5% and 7.5%, respectively. The batch fermentation of immobilized cells on PEI-GA cotton fiber was repeated seven times. The concentration of scuccinic acid, yield and productivity did not decrease. It suggested that PEI-GA cotton fiber as immobilization carrier was suitable for scuccinic acid production by Escherichia coli AFP111.