The Production Of L-tryptophan By Recombinant Escherichia Coli

L-tryptophan is one of the essential amino acids in humans and animals,and has a wide range of applications in food,feed,medicine and chemical industries.With the development of L-tryptophan range,the demand for L-tryptophan is increasing dramatically.With the continuous progress of systems biology,synthetic biology and metabolic engineering,the integration of various types of group information,for the improvement of L-tryptophan production strains more accurate and comprehensive strategy.It has been found that the weakening system and transport system in the process of L-tryptophan biosynthesis of E.coli are critical to the ability of cells to largely accumulate L-tryptophan.In this study,based on the high-yield L-tryptophan engineering bacteria obtained in the early stage of the laboratory,the transfectant TrpR and L-tryptophan transporter TnaB in the L-tryptophan biosynthesis were modified,A new strain of L-tryptophan was obtained by combining the single factor and multivariate fermentation medium and the process to obtain a new engineering strain with significant increase in L-tryptophan production.And the successful realization of 50L cans fed batch fermentation verification work.1.TrpR,tnaB single knockout strain and trpR/tnaB double gene knockout strain were constructed by Red System.To investigate the effect on L-tryptophan production after gene knockout.The results showed that trpR/tnaB double gene knockout bacteria had the greatest effect on the synthesis of L-tryptophan.2.On the basis of the original culture medium,the new L-tryptophan engineering strain was optimized by single factor and multi-factor shake flask fermentation medium to obtain the optimal fermentation medium of L-tryptophan.Compared with the original medium,the acid production increased by 45.3%.3.On the basis of the optimization of the fermentation medium and the process of the flask,the modified strain was subjected to batch fermentation of 50L cans,and the parameters of the fermentation broth were determined by controlling the dissolved oxygen,pH and glucose concentration in the fermentation broth.The maximum concentration of tryptophan reached 38.0g/L,which was 13.2%higher than that of the original engineering strain.