基于组合代谢工程策略改造大肠杆菌合成L-色氨酸OA

L-tryptophan,an essential amino acid for humans,has wide applications in food,feed additives,and pharmaceuticals.This study applied systematic metabolic engineering to modify the L-tryptophan synthesis pathway,significantly improving its production.The tnaA gene was knocked out to reduce L-tryptophan degradation.Knockout of pheA,tyrA,and poxB genes eliminated carbon flux diver-sion through competing pathways.Global regulatory genes fruR,tyrR,and trpR were modified to redirect carbon flow.To enhance precursor supply,tktA and the galp-glk glucose transport system were integrated.Additionally,deleting the amn gene and overexpressing pntAB in-creased the supply of ATP and NADPH,optimizing energy metabolism.Furthermore,L-tryptophan secretion was enhanced while its uptake was reduced.These modifications resulted in the engineered strain XZ14.During fed-batch fermentation in a 5 L bioreactor,this strain a-chieved an L-tryptophan yield of 37.4 g/L,with a yield of 16.7％from glucose.These results establish a solid foundation for industrial application.