Microbial Strain Gene Modification for Glutathione Yield
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Solution Overview
Problem
Current methods for producing glutathione and associated compounds like γ-glutamylcysteine, bis-γ-glutamylcystine, γ-glutamylcystine, reduced glutathione, and oxidized glutathione through microbial fermentation are not efficient enough, limiting productivity.
Innovation Solution
A microbial strain with specific gene modifications, including disruption of genes encoding phosphoglycerate mutase and enhanced expression of genes encoding γ-glutamyltransferase, glutamate-cysteine ligase, and glutathione synthetase, is used for fermentation to enhance the production of these compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fermentation methods are used for glutathione production, then the production process is simple, but the productivity is low
Solution Approach 1:
The patent segments the glutathione biosynthesis pathway into multiple target genes for independent modification: gshA (γ-glutamylcysteine synthetase), gshB (glutathione synthetase), and gshF (bifunctional enzyme). By separately enhancing each gene's expression, the patent achieves cumulative improvement in productivity while managing complexity through modular genetic engineering approaches.
Solution Approach 2:
The patent changes key parameters of the microbial strain by disrupting phosphoglycerate mutase genes (pgmA, pgmB) to alter metabolic flux, and by enhancing the expression levels of glutathione biosynthesis genes through promoter optimization and copy number increase. These parameter changes collectively improve glutathione production efficiency from 160 mg/l to significantly higher yields.
2Productivity
If phosphoglycerate mutase genes are disrupted to improve glutathione production, then productivity increases, but metabolic stability may be affected
Solution Approach 1:
The patent introduces alternative metabolic pathways as intermediaries to compensate for phosphoglycerate mutase disruption. By enhancing gshA, gshB, and gshF expression, the patent creates alternative routes for glutathione synthesis that bypass the blocked phosphoglycerate metabolism, thereby maintaining metabolic stability while improving glutathione productivity.
Solution Approach 2:
The patent converts the harmful effect of phosphoglycerate mutase disruption (metabolic instability) into a benefit by redirecting metabolic flux toward glutathione synthesis. The disruption of pgmA/pgmB genes, which would normally harm cellular metabolism, is compensated by overexpressing glutathione biosynthesis genes, transforming the metabolic imbalance into increased glutathione yield.
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 modified microbial strain significantly improves the production efficiency of the target compounds, achieving higher yields compared to traditional methods.
Implementation Method 1
A microbial strain with specific gene modifications, including disruption of genes encoding phosphoglycerate mutase and enhanced expression of genes encoding γ-glutamyltransferase, glutamate-cysteine ligase, and glutathione synthetase, is used for fermentation to enhance the production of these compounds.
Implementation Method 2
enhanced expression of the gene [3] or [4]: [3] a gene encoding glutamate-cysteine ligase (EC:6.3.2.2) and/or a gene encoding glutathione synthetase (EC:6.3.2.3); and [4] a gene encoding bifunctional glutathione synthetase
Data Source
AI summary
One or more embodiments of the present invention provide a microbial strain with improved productivity of γ-glutamylcysteine, bis-γ-glutamylcystine, γ-glutamylcystine, reduced glutathione, and/or oxidized glutathione. Such microbial strain has disruption of [1] a gene encoding γ-glutamyltransferase and [2] a gene encoding phosphoglycerate mutase and enhanced expression of [3] a gene encoding glutamate-cysteine ligase and/or a gene encoding glutathione synthetase or [4] a gene encoding bifunctional glutathione synthetase. This invention also discloses a method for producing the substances mentioned above via culture of the microbial strain.