L-Valine Producing Strain via α-Acetolactate Flux Redirection
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Solution Overview
Problem
Current methods for producing L-valine through microbial fermentation, such as using Corynebacterium glutamicum and Escherichia coli, suffer from low production efficiency and substrate conversion rates, making it difficult to meet industrial requirements.
Innovation Solution
Genetically engineer 2,3-butanediol or acetoin producing strains by inhibiting the synthesis of by-products like acetoin and 2,3-butanediol, and introducing an exogenous L-valine biosynthetic pathway, optimizing L-valine synthetic flux and efflux, and redirecting α-acetolactate metabolic flow to enhance L-valine production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fermentation methods using C. glutamicum or E. coli are used, then L-valine production is achieved, but production efficiency and substrate conversion rate are low
Solution Approach 1:
The patent changes key metabolic parameters by introducing heterologous genes (ilvC, ilvD, ilvE, bcd, alsS) to alter the metabolic flux distribution. This redirects carbon flow from the original fermentation pathways toward L-valine synthesis, achieving higher production efficiency (up to 2.14 g/L/h) and substrate conversion rate (up to 0.587 g/g) while maintaining the fermentation system framework
Solution Approach 2:
The patent segments the metabolic pathway into distinct functional modules: alpha-acetolactate synthesis (alsS), isomeroreduction (ilvC), dehydration (ilvD), and transamination (bcd). By independently optimizing each segment through targeted gene introduction and knockout strategies, the overall L-valine production efficiency is improved without requiring complete pathway reconstruction
2Productivity
If by-product synthesis pathways are active, then strain metabolism is balanced, but L-valine production is reduced due to metabolic flux diversion
Solution Approach 1:
The patent extracts and removes competing metabolic pathways by knocking out specific genes (budA for acetoin synthesis, budC and gldA for 2,3-butanediol synthesis, pta for acetate synthesis). This eliminates the diversion of metabolic flux toward by-products, concentrating carbon flow toward L-valine production and achieving higher purity and yield
Solution Approach 2:
The patent converts the metabolic bottleneck at alpha-acetolactate (the precursor for both L-valine and by-products) into a benefit by introducing high-activity heterologous enzymes (alsS from Bacillus subtilis). This ensures sufficient precursor supply for L-valine synthesis while the subsequent pathway blockages prevent by-product formation, turning the branching point into a unidirectional flow toward the desired product
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The engineered strains achieve high yields and production intensities of L-valine, with yields up to 0.587 g/g and production rates up to 2.14 g/L/h, using simple fermentation media and cost-effective substrates.
Implementation Method 1
increasing the synthesis of α-acetolactate
Implementation Method 2
microbial fermentation technology
Data Source
AI summary
The present invention provides a method for constructing an L-valine production strain, the L-valine production strain, and use thereof. According to the method for constructing the L-valine-producing strain, a 2,3-butanediol- or acetoin-producing strain is used as a starting strain, and genetic engineering modification is performed on the strain to improve the L-valine yield thereof. The present invention provides a new thought and way for efficient production of L-valine, and obtains a new production strain for efficiently producing L-valine. The L-valine-producing strain obtained in the present invention requires a simple culture medium and has low fermentation substrate and culture costs; meanwhile, the strain has a high L-valine yield and has a single product component easy to separate.