文摘
Product yields in microbial synthesis are ultimately limited by the mechanism utilizedfor glucose transport. Altered expression of phosphoenolpyruvate synthase wasexamined as a method for circumventing these limits. Escherichia coli KL3/pJY1.216Awas cultured under fed-batch fermentor conditions where glucose was the only sourceof carbon for the formation of microbial biomass and the synthesis of product3-dehydroshikimic acid. Shikimate pathway byproducts 3-deoxy-D-arabino-heptulosonicacid, 3-dehydroquinic acid, and gallic acid were also generated. An optimal expressionlevel of phosphoenolpyruvate synthase was identified, which did not correspond tothe highest expression levels of this enzyme, where the total yield of 3-dehydroshikimicacid and shikimate pathway byproducts synthesized from glucose was 51% (mol/mol).For comparison, the theoretical maximum yield is 43% (mol/mol) for synthesis of3-dehydroshikimic acid and shikimate pathway byproducts from glucose in lieu ofamplified expression of phosphoenolpyruvate synthase.