Yi Jian, Li Kai, Draths K M, Frost J W
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Biotechnol Prog. 2002 Nov-Dec;18(6):1141-8. doi: 10.1021/bp020101w.
Product yields in microbial synthesis are ultimately limited by the mechanism utilized for glucose transport. Altered expression of phosphoenolpyruvate synthase was examined as a method for circumventing these limits. Escherichia coli KL3/pJY1.216A was cultured under fed-batch fermentor conditions where glucose was the only source of carbon for the formation of microbial biomass and the synthesis of product 3-dehydroshikimic acid. Shikimate pathway byproducts 3-deoxy-D-arabino-heptulosonic acid, 3-dehydroquinic acid, and gallic acid were also generated. An optimal expression level of phosphoenolpyruvate synthase was identified, which did not correspond to the highest expression levels of this enzyme, where the total yield of 3-dehydroshikimic acid and shikimate pathway byproducts synthesized from glucose was 51% (mol/mol). For comparison, the theoretical maximum yield is 43% (mol/mol) for synthesis of 3-dehydroshikimic acid and shikimate pathway byproducts from glucose in lieu of amplified expression of phosphoenolpyruvate synthase.
微生物合成中的产物产量最终受到葡萄糖转运机制的限制。研究了磷酸烯醇丙酮酸合酶表达的改变，作为一种规避这些限制的方法。在补料分批发酵罐条件下培养大肠杆菌KL3/pJY1.216A，其中葡萄糖是形成微生物生物质和合成产物3-脱氢莽草酸的唯一碳源。还生成了莽草酸途径的副产物3-脱氧-D-阿拉伯庚糖酸、3-脱氢奎尼酸和没食子酸。确定了磷酸烯醇丙酮酸合酶的最佳表达水平，该水平与该酶的最高表达水平不一致，此时由葡萄糖合成的3-脱氢莽草酸和莽草酸途径副产物的总产量为51%（摩尔/摩尔）。作为比较，在未扩增磷酸烯醇丙酮酸合酶表达的情况下，由葡萄糖合成3-脱氢莽草酸和莽草酸途径副产物的理论最大产量为43%（摩尔/摩尔）。
