Engineered Corynebacterium Strain for Glucose-Based Theanine Fermentation
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Solution Overview
Problem
Existing methods for theanine production, such as plant separation and extraction, plant tissue cell culture, and chemical synthesis, are limited by high costs, environmental pollution, and low yields, while microbial methods face challenges due to low ethylamine availability and enzyme limitations, particularly alanine decarboxylase, which restricts theanine synthesis.
Innovation Solution
A genetically engineered Corynebacterium glutamicum strain is developed with a mutated alanine decarboxylase (CsAlaDC-I177Y) and overexpressed genes (gltA, pyk, gdh, and alaA) to enable de novo theanine synthesis from glucose without exogenous precursors, enhancing yield and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If plant separation and extraction method is used for theanine production, then theanine can be obtained from tea plants, but the production cost is high and the scale is limited
Solution Approach 1:
The patent uses microbial cells themselves as bioreactors to synthesize theanine directly from simple substrates like glucose and ammonium salts. The engineered bacteria perform the complete theanine synthesis pathway internally, eliminating the need for expensive plant extraction processes and complex separation equipment, thereby significantly reducing production costs while scaling up manufacturing capacity.
2Quantity of substance
If chemical synthesis method is used for theanine production, then theanine can be synthesized chemically, but the separation cost is high and product yield is low with many byproducts
Solution Approach 1:
The patent replaces chemical synthesis mechanisms with biological enzymatic mechanisms. The engineered microorganisms use natural enzymes (γ-glutamylmethylamine synthetase and other pathway enzymes) to catalyze the formation of L-theanine from glucose and ammonium salts. This biological system provides high stereospecificity, producing only L-theanine without D-type byproducts or other chemical reaction byproducts, thereby eliminating the need for costly separation and purification processes.
3Productivity
If microbial method is used for theanine production, then production cost is reduced and catalytic efficiency is improved, but ethylamine availability is limited and enzyme expression is insufficient
Solution Approach 1:
The patent performs preliminary genetic engineering modifications before theanine production. The microorganisms are pre-engineered with the complete theanine synthesis pathway genes (including gmas, ggt, and other pathway genes) and optimized metabolic routes. This preliminary genetic preparation enables the cells to autonomously synthesize all necessary intermediates including ethylamine from glucose, eliminating the need for external ethylamine supplementation and ensuring sufficient substrate availability for high-productivity theanine synthesis.
4Quantity of substance
If alanine decarboxylase is used for ethylamine synthesis, then theanine can be produced, but the enzyme expression is low and theanine yield is limited
Solution Approach 1:
The patent optimizes multiple parameters of the alanine decarboxylase enzyme system. The enzyme is engineered with improved catalytic parameters including higher specific activity, enhanced stability at fermentation temperatures, and optimized pH profile. Additionally, the gene expression parameters are optimized through strong promoters and appropriate ribosome binding sites, resulting in high-level enzyme expression that directly increases ethylamine production rate and consequently theanine 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 strain achieves a theanine yield of 51.3 g/L in a 5 L fermentation tank, improving production efficiency by 85% compared to previous methods, and significantly enhances theanine content in tea fermentation.
Implementation Method 1
a mutated alanine decarboxylase (CsAlaDC-I177Y) to enable de novo theanine synthesis from glucose
Implementation Method 2
The strain achieves a theanine yield of 51.3 g/L in a 5 L fermentation tank
Data Source
AI summary
Provided are a theanine-producing strain and use thereof in tea fermentation production. A Corynebacterium glutamicum is proposed, which includes an alanine decarboxylase CsAlaDC mutant. The theanine-producing strain is obtained by taking the Corynebacterium glutamicum as a starting strain, knocking out in sequence an α-ketoglutarate dehydrogenase E1 subunit gene odhA, a glutamate external transporter gene Ncg11221 and a lactate dehydrogenase gene ldh; and/or expressing a citrate synthase gene gltA, a pyruvate kinase gene pyk and a glutamate dehydrogenase gene gdh; and/or overexpressing an alanine dehydrogenase alaA and integrating a γ-glutamine synthetase GMAS into a cg1960 pseudogene locus of the Corynebacterium glutamicum.