Engineered E. coli Ergothioneine Pathway for Higher Fermentation Yield
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Solution Overview
Problem
Current methods for producing ergothioneine using engineered bacteria have low yield levels, posing a challenge for industrial production.
Innovation Solution
Integrate a constitutive promoter PrrnD and an ergothioneine-synthesizing gene cluster MnegtABCDE from Mycolicibacterium neoaurum into the genome of Escherichia coli, and mutate glutamate at position 271 in ATP phosphoribosyltransferase HisG to Escherichia coli, enhancing the bacteria's ability to synthesize ergothioneine from glucose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fermentation with genetically engineered bacteria is used to produce ergothioneine, then the process simplicity and production efficiency are improved, but the ergothioneine yield level remains relatively low
Solution Approach 1:
The patent divides the ergothioneine synthesis pathway into multiple gene clusters (egtABCDE, hisG, and other auxiliary genes) that are independently cloned and then integrated into the bacterial genome. This segmentation allows for systematic optimization of each pathway component to enhance overall productivity while maintaining manageable process complexity.
Solution Approach 2:
The patent employs multiple parameter changes including: (1) replacing the native promoter with a strong constitutive promoter (PrrnD) to maximize gene expression; (2) mutating the HisG enzyme (Glu271Lys substitution) to eliminate feedback inhibition and increase histidine precursor availability; (3) optimizing codon usage for E. coli expression; and (4) integrating genes into the genome rather than using plasmids to ensure stability during large-scale fermentation.
2Reliability
If mushroom extraction method is used, then ergothioneine can be obtained naturally, but the product contains impurities such as proteins, polypeptides, and polysaccharides
Solution Approach 1:
The patent replaces the mechanical extraction process (ultrasonic shearing and water extraction from mushrooms) with a biological synthesis system using genetically engineered bacteria. This substitution produces ergothioneine through metabolic pathways, yielding a pure product without co-extraction of proteins, polypeptides, or polysaccharides, thereby simplifying the manufacturing process while ensuring product purity.
Solution Approach 2:
The engineered bacteria autonomously synthesize ergothioneine through their metabolic pathways, converting glucose and other simple substrates into the target compound. This self-service capability eliminates the need for complex extraction and purification steps required by mushroom-based methods, as the bacteria naturally produce pure ergothioneine as a metabolic endpoint.
3Reliability
If chemical synthesis method is used, then high chiral purity can be achieved, but organic solvents such as toluene, chloroform, and acetonitrile are required
Solution Approach 1:
The patent replaces chemical synthesis methods (which require organic solvents like toluene, chloroform, and acetonitrile) with biological synthesis using engineered bacteria. The bacterial system performs stereospecific synthesis through enzymatic pathways, achieving high chiral purity of L-ergothioneine without requiring any organic solvents, thereby eliminating the harmful factors associated with chemical synthesis.
Solution Approach 2:
The patent changes the fundamental synthesis parameter from chemical catalysis to biological catalysis. By expressing the egt gene cluster in bacterial hosts, the synthesis occurs through enzyme-mediated reactions in aqueous environments, maintaining high chiral purity through the inherent stereospecificity of the enzymes while completely avoiding organic solvent usage.
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 bacteria achieve a high ergothioneine content of 99% or more, suitable for large-scale industrial production with reduced material costs and improved application safety.
Implementation Method 1
The engineered bacteria achieve a high ergothioneine content of 99% or more, suitable for large-scale industrial production
Data Source
AI summary
Ergothioneine-producing engineered bacteria and a construction method and use thereof are provided. The construction method includes: integrating a constitutive promoter PrrnD and an ergothioneine-synthesizing gene cluster egtABCDE derived from Mycolicibacterium neoaurum into a genome of Escherichia coli as a starting strain; and further mutating glutamate at a position 271 in an ATP phosphoribosyltransferase (HisG) gene of a strain produced above into lysine to produce the ergothioneine-producing engineered bacteria. With glucose as a main raw material, a fermentation culture can be conducted with the engineered bacteria to produce ergothioneine. The fermentation with the engineered bacteria to synthesize ergothioneine has advantages such as simple process and high production efficiency, can avoid the use of organic solvents and antibiotics in large quantities, and is suitable for industrial production.