Recombinant E. coli Strain Engineering for Stable L-Threonine Fermentation
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Solution Overview
Problem
Conventional methods for producing L-threonine using microbial fermentation face challenges in achieving high yield and stability due to random mutations in bacterial strains, leading to slow growth and increased byproduct formation.
Innovation Solution
A recombinant Escherichia coli strain is developed through site-directed mutagenesis of specific genes (kdtA, spoT, and yebN) to introduce targeted mutations, enhancing L-threonine production efficiency and strain stability, using plasmids like pKOV for vector construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional mutation breeding is used to produce L-threonine, then production cost is reduced, but strain growth speed decreases and byproduct formation increases
Solution Approach 1:
The patent applies site-directed mutagenesis to precisely modify specific genes (kdtA, spoT, yebN) in the E. coli genome, changing the genetic parameters to optimize L-threonine production. This targeted approach allows control over growth rate and byproduct formation while maintaining low production costs through efficient genetic modification
Solution Approach 2:
The patent segments the complex metabolic pathway into specific target genes (kdtA, spoT, yebN) and modifies each independently through site-directed mutagenesis. This segmentation allows precise control over different aspects of L-threonine production without affecting the entire metabolic system, resolving the contradiction between cost and productivity
2Ease of manufacture
If conventional mutation breeding is used to produce L-threonine, then production cost is reduced, but L-threonine yield decreases
Solution Approach 1:
The patent uses site-directed mutagenesis to precisely alter genetic parameters of specific genes, optimizing the balance between production cost and L-threonine yield. By targeting specific metabolic enzymes through controlled genetic modification, the patent achieves high yield without the random mutations that characterize conventional breeding methods
Solution Approach 2:
The patent replaces the mechanical/random process of conventional mutation breeding with a precise molecular biology technique (site-directed mutagenesis). This substitution allows controlled modification of specific genes to maximize L-threonine yield while maintaining cost-effectiveness through targeted rather than random genetic changes
3Adaptability or versatility
If random mutation is used to create production strains, then genetic diversity is increased, but strain stability decreases
Solution Approach 1:
The patent changes the approach from random genetic variation to controlled parameter modification by targeting specific genes (kdtA, spoT, yebN) for mutagenesis. This precise control maintains strain stability while still achieving the necessary genetic diversity for improved L-threonine production through deliberate rather than random changes
4Quantity of substance
If site-directed mutagenesis is used to modify specific genes, then L-threonine yield is improved, but construction complexity increases
Solution Approach 1:
The patent segments the complex genetic modification task into manageable parts by targeting specific genes (kdtA, spoT, yebN) individually through site-directed mutagenesis. This segmentation makes the construction process more systematic and controllable, reducing overall complexity through structured approach to genetic modification
Data Source
AI summary
The present disclosure discloses an Escherichia coli-based kdtA-gene-modified recombinant strain, a construction method therefor and use thereof. A mutant gene obtained by subjecting a wild-type kdtA gene (ORF sequence is shown in a sequence 73556-74833 in GenBank accession No. CP032667.1), a wild-type spoT gene (ORF sequence is shown in a sequence 3815907-3818015 in GenBank accession No. AP009048.1) and a wild-type yebN gene (ORF sequence is shown in a sequence 1907402-1907968 in GenBank accession No. AP009048.1) of an E. coli K12 strain and a derivative strain thereof (such as MG1655 and W3110) to site-directed mutagenesis, and a recombinant strain obtained therefrom can be used for the production of L-threonine, and compared with an unmutated wild-type strain, the obtained strain can produce L-threonine with a higher concentration and has good strain stability, and also has lower production cost as an L-threonine production strain.