Construction of Recombinant Escherichia coli with a High L-Phenylalanine Production Yield from Glucose

Abstract

L-phenylalanine is an important aromatic amino acid that is widely used in the area of feed, food additives, and pharmaceuticals. Among the different strategies of L-phenylalanine synthesis, direct microbial fermentation from raw substrates has attracted more and more attention due to its environment friendly process and low-cost raw materials. In this study, a rational designed recombinant Escherichia coli was constructed for L-phenylalanine production. Based on wild type E. coli MG1655, multilevel engineering strategies were carried out, such as directing more carbon flux into the L-phenylalanine synthetic pathway, increasing intracellular level of precursors, blocking by-product synthesis pathways and facilitating the secretion of L-phenylalanine. During 5 L fed batch fermentation, recombinant E. coli MPH-3 could produce 19.24 g/L of L-phenylalanine with a yield of 0.279 g/g glucose. To the best of our knowledge, this is one of the highest yields of L-phenylalanine producing E. coli using glucose as the sole carbon source in fed-batch fermentation.