초록
<P><B>Abstract</B></P> <P>The fructose repressor (FruR) affects carbon flux through the central metabolic pathways of <I> <I>Escherichia</I> coli</I>. In this study, <SMALL>L</SMALL>-tryptophan production in <I>Escherichia coli</I> FB-04 was improved by knocking out the <I>fruR</I> gene, thereby inactivating FruR. This <I>fruR</I> knockout strain, <I>E. coli</I> FB-04(<I>ΔfruR</I>), not only exhibited higher growth efficiency, it also showed substantially improved <SMALL>L</SMALL>-tryptophan production. <SMALL>L</SMALL>-tryptophan production by <I>E. coli</I> FB-04(<I>ΔfruR</I>) and <SMALL>L</SMALL>-tryptophan yield per glucose were increased by 62.5% and 52.4%, respectively, compared with the parent <I>E. coli</I> FB-04. Metabolomics analysis showed that the <I>fruR</I> knockout significantly enhances metabolic flow through glycolysis, the pentose phosphate pathway and the TCA cycle, increasing levels of critical precursors and substrates for <SMALL>L</SMALL>-tryptophan biosynthesis. These results indicate that <I>fruR</I> deletion should enhance <SMALL>L</SMALL>-tryptophan production and improve the efficiency of carbon source utilization independent of genetic background.</P> <P><B>Highlights</B></P> <P> <UL> <LI> FruR was inactivated in <SMALL>L</SMALL>-tryptophan production strain <I>Escherichia coli</I> FB-04, forming FB-04(<I>ΔfruR</I>). </LI> <LI> FB-04(<I>ΔfruR</I>) maintained higher vitality and growth efficiency. </LI> <LI> FB-04(<I>ΔfruR</I>) showed substantially improved <SMALL>L</SMALL>-tryptophan production. </LI> <LI> Knockout of <I>fruR</I> improved the efficiency of the carbon source utilization. </LI> <LI> Knockout of <I>fruR</I> improved the levels of critical precursors and substrates for <SMALL>L</SMALL>-tryptophan biosynthesis by modulating the direction of carbon flow. </LI> </UL> </P>