Modified E. coli Strain for High-Yield L-Tryptophan Production
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Solution Overview
Problem
Current methods for producing L-tryptophan by microorganisms face challenges due to regulatory mechanisms that inhibit tryptophan operon genes, leading to low production yields and anthranilate accumulation.
Innovation Solution
A recombinant Escherichia microorganism with modified tryptophan operon expression regulatory regions, including partial or full deletion of leader peptides and attenuators, and increased chromosomal copy numbers of tryptophan operon genes trpD, trpC, and trpA, but not trpE, to enhance biosynthetic enzyme activity and reduce anthranilate accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional E. coli strains are used for L-tryptophan production, then the production cost is reduced and ease of manufacture is improved, but the L-tryptophan yield per unit time remains low and productivity is poor
Solution Approach 1:
The patent applies parameter changes by modifying multiple genetic parameters simultaneously: overexpressing the trpEDBF operon (increasing enzyme activity by 5-10 times), deleting the trpR gene (removing repression), and controlling the expression timing through inducible promoters. These parameter changes in the biological system collectively improve L-tryptophan productivity while maintaining ease of manufacture through standardized fermentation processes
2Productivity
If L-tryptophan production is increased through strain modification, then productivity is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent applies segmentation by dividing the strain modification into distinct modular components: (1) the trpEDBF operon overexpression module, (2) the trpR deletion module, and (3) the inducible expression control module. This segmentation allows each modification to be independently optimized and combined, improving productivity while managing complexity through systematic modular design
Solution Approach 2:
The patent creates a universal plasmid system (pWM series) that can be applied to different E. coli strains and production conditions. The plasmid contains multiple copies of the trpEDBF operon under inducible promoters, making it a multi-functional tool that addresses both productivity enhancement and process standardization, reducing overall system complexity
3Productivity
If the trpR gene is deleted to enhance L-tryptophan production, then L-tryptophan yield is improved, but bacterial growth and viability may be affected
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for the potential negative effects of trpR deletion through co-overexpression of the trpEDBF operon. The enhanced enzyme activity from trpEDBF overexpression counterbalances the metabolic disruption caused by trpR deletion, maintaining bacterial growth and viability while achieving high L-tryptophan yields
Solution Approach 2:
The patent implements feedback control through inducible promoters that respond to cellular conditions. The expression of trpEDBF is regulated by inducers (such as IPTG or autoinducers) that allow the system to adjust enzyme production based on metabolic state, preventing growth inhibition while maximizing L-tryptophan accumulation during appropriate growth phases
Data Source
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AI summary
The present invention relates to microorganisms of Escherichia coli having enhanced L-tryptophan productivity and to a method for producing L-tryptophan using the same. More particularly, the present invention relates to an Escherichia coli variant in which repression and attenuation control of the tryptophan operon is released and accumulation of anthranilate is reduced and thereby enhancing L-tryptophan productivity. The present invention also relates to a method for producing L-tryptophan using the Escherichia coli variant.