Modulating the direction of carbon flow in Escherichia coli to improve l-tryptophan production by inactivating the global regulator FruR.

The fructose repressor (FruR) affects carbon flux through the central metabolic pathways of Escherichia coli . In this study, l -tryptophan production in Escherichia coli FB-04 was improved by knocking out the fruR gene, thereby inactivating FruR. This fruR knockout strain, E. coli FB-04( ΔfruR ), not only exhibited higher growth efficiency, it also showed substantially improved l -tryptophan production. l -tryptophan production by E. coli FB-04( ΔfruR ) and l -tryptophan yield per glucose were increased by 62.5% and 52.4%, respectively, compared with the parent E. coli FB-04. Metabolomics analysis showed that the fruR knockout significantly enhances metabolic flow through glycolysis, the pentose phosphate pathway and the TCA cycle, increasing levels of critical precursors and substrates for l -tryptophan biosynthesis. These results indicate that fruR deletion should enhance l -tryptophan production and improve the efficiency of carbon source utilization independent of genetic background. [ABSTRACT FROM AUTHOR]