Effect of Immobilization on Metabolism of Escherichia Coli: Research Planning Grant

在过去几年中，固定化全细胞进行生化转化的使用显著增加。其中一个最重要的领域是固定化对细胞内在代谢的影响。关于固定化如何影响碳流、能量产生和产物形成，特别是关于大肠杆菌的报道很少。初步结果表明，固定化后代谢发生显著变化。在海藻酸盐中生长的大肠杆菌细胞每个细胞合成的-半乳糖苷酶显著增加，正常代谢副产物醋酸盐、丙酮酸盐和乳酸盐的数量也有所增加。与自由细胞相比。这些结果支持了固定化改变碳消耗和碳增长相对速率的假设。这项工作的具体目标是测试以下两个假设：1)固定细胞消耗的多余碳被转移到酸副产物或诱导蛋白的合成中；ii)对酸副产物去除的传质限制导致了所观察到的代谢变化。最终目标是利用固定化诱导的代谢变化来过量生产重组蛋白。

The use of immobilized whole cells to conduct biochemical conversions has increased significantly in the last several years. One of the most important areas is the effects of immobilization on the intrinsic metabolism of the cells employed. Little has been reported, particularly with respect to E. coli, on how immobilization affects carbon flow, energy production, and product formation. Preliminary results have shown that significant changes in metabolism occur upon immobilization. E. coli cells grown in alginate synthesize significantly more beta-galactosidase per cell, and elevated quantities of the normal metabolic byproducts acetate, pyruvate, and lactate, compared to free cells. These results support the hypothesis that immobilization changes the relative rates of carbon consumption and growth. The specific objectives of this work are to test the following two hypotheses: i) that the excess carbon consumed by immobilized cells is diverted to the synthesis of acid byproducts or of inducible protein; and ii) that mass transfer limitations on the removal of acid byproducts cause the observed changes in metabolism. The ultimate goal is to exploit immobilization-induced metabolic changes for the overproduction of recombinant proteins.