Engineered E. coli for Sarcosine Production via Metabolic Pathway Optimization
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Solution Overview
Problem
Current methods for sarcosine production, such as chemical synthesis, face challenges like harsh reaction conditions and difficult product separation, and existing microbial fermentation methods have limitations in yield and efficiency.
Innovation Solution
A genetically engineered strain of Escherichia coli is developed using a high-efficiency imine reductase from Brevibacterium linens, integrated with specific genetic modifications and CRISPR/Cas9-mediated gene editing, to enhance sarcosine synthesis with glucose as a cheap carbon source, optimizing metabolic pathways for high-yield production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical synthesis method is used for sarcosine production, then production efficiency can be improved, but reaction conditions become harsh and product separation becomes difficult
Solution Approach 1:
The patent replaces chemical synthesis methods with biological fermentation using genetically engineered Escherichia coli. The engineered strain expresses imine reductase enzyme that catalyzes the reduction of N-methylglycine to sarcosine under mild physiological conditions, eliminating the need for harsh chemical reagents and extreme reaction conditions while maintaining high production efficiency
Solution Approach 2:
The patent introduces an intermediary enzyme system (imine reductase) that mediates the conversion of substrates to sarcosine. This enzyme acts as a biocatalyst that facilitates the reaction under gentle conditions, serving as a bridge between simple substrates and the target product without requiring harsh chemical environments
2Productivity
If existing microbial fermentation methods are used, then production can be achieved, but yield and efficiency are limited
Solution Approach 1:
The patent employs multiple parameter changes including: (1) changing the host organism to Escherichia coli with superior growth characteristics; (2) optimizing enzyme expression levels through promoter selection and gene dosage control; (3) adjusting metabolic flux by overexpressing key pathway enzymes; (4) modifying cellular redox balance to favor NADPH production. These parameter optimizations collectively enhance both production efficiency and final yield
Solution Approach 2:
The patent implements preliminary metabolic engineering modifications before fermentation, including pre-optimizing the expression systems, pre-adjusting the metabolic pathways, and pre-selecting the optimal host strain. These preliminary actions ensure that the fermentation process starts with a highly optimized cellular factory, maximizing subsequent production efficiency and yield
3Reliability
If expensive substrates are used for fermentation, then product quality can be maintained, but production cost increases
Solution Approach 1:
The patent utilizes inexpensive, readily available substrates such as glucose and methylamine as carbon and nitrogen sources, respectively. These cheap substrates replace expensive specialized media components, significantly reducing production costs while the engineered strain efficiently converts them into high-quality sarcosine product through its optimized metabolic pathways
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 strain achieves a sarcosine titer of 10 g/L, the highest reported value, with improved yield and efficiency, and has good industrial application prospects due to its ability to use inexpensive substrates and optimized metabolic pathways.
Implementation Method 1
Imine reductase DpkA (IRED) is an enzyme that can actively reduce imine bonds in cyclic and aliphatic compounds and can reduce piperidine-2-carboxylic acid into L-pipecolic acid
Implementation Method 2
This reaction needs NADPH to provide a reducing force
Implementation Method 3
This reaction needs NADPH to provide a reducing force
Implementation Method 4
new metabolic engineering strategies are used to construct an engineered Escherichia coli for high-yield sarcosine production with glucose as carbon source
Data Source
AI summary
The disclosure discloses a genetically engineered strain for sarcosine production as well as a construction method and application. The genetically engineered strain is obtained by using Escherichia coli as a host and by integrating a single copy of imine reductase gene dpkA on its genome; singly copying citrate synthase gene gltA; knocking out glyoxylate cycle inhibitor gene iclR; knocking out malate synthase gene aceB; integrating a single copy of isocitrate lyase gene aceA; integrating a single copy of membrane-bound transhydrogenase gene pntAB; knocking out 2-ketate reductase gene ycdW; integrating a single copy of phosphoenolpyruvate carboxylase gene ppc; and knocking out pyruvate kinase gene pykF. After system metabolism transformation, the engineered strain can synthesize sarcosine with glucose and methylamine as main raw materials. The sarcosine titer can reach 10 g/L after fermentation for 30 h in a 5 L fermenter.