Engineered E. coli Strain for CO2 Fixation to Malic Acid
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Solution Overview
Problem
Current CO2 storage technologies are energy-intensive and costly, and traditional methods produce harmful byproducts, while CO2 fixation with heterotrophic microorganisms is limited in product spectrum and efficiency, especially for producing malic acid, which is a valuable chemical compound.
Innovation Solution
An engineered strain of E. coli is developed by knocking out specific genes and overexpressing others to construct a CO2 fixation pathway, allowing the bacteria to produce malic acid efficiently through fermentation, with a focus on integrating CO2 fixation into the glycolysis pathway to enhance fixation efficiency and product spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional physical and chemical methods are used for CO2 storage, then CO2 capture efficiency is improved, but energy consumption and operating costs increase significantly
Solution Approach 1:
The engineered E. coli strain uses its own metabolic pathways to fix CO2 into malic acid, eliminating the need for external energy-intensive capture systems. The bacteria naturally convert CO2 into valuable chemicals through endogenous carboxylation reactions and artificially constructed metabolic routes, making the system self-sufficient and energy-efficient
Solution Approach 2:
The patent converts harmful CO2 emissions into valuable L-malic acid, a high-added-value chemical compound. By engineering E. coli to overexpress key enzymes in CO2 fixation pathways, the system transforms greenhouse gas into useful products, simultaneously addressing environmental concerns and creating economic value
2Productivity
If endogenous carboxylation reaction is improved in heterotrophic microorganisms, then CO2 fixation capability is enhanced, but product spectrum is limited
Solution Approach 1:
The patent divides the CO2 fixation process into multiple independent enzymatic steps, each catalyzed by a specific overexpressed enzyme. This segmentation allows independent optimization of each reaction step and enables flexible production of different products by adjusting which pathways are enhanced
Solution Approach 2:
The engineered E. coli strain possesses multiple CO2 fixation pathways simultaneously, including the Calvin cycle, reductive TCA cycle, and artificially constructed pathways. This multi-functionality enables the bacteria to produce a broad spectrum of chemicals from CO2, not limited to single products
3Productivity
If CO2 fixation pathways are artificially constructed and ligated to glycolysis, then CO2 fixation efficiency is improved, but metabolic pathway complexity increases
Solution Approach 1:
The patent merges artificially constructed CO2 fixation pathways with the native glycolysis pathway in E. coli, creating an integrated metabolic network. Key enzymes from different pathways are co-expressed and coordinated to work together, simplifying the overall system while maintaining high CO2 fixation efficiency
Solution Approach 2:
The patent optimizes multiple parameters including enzyme expression levels, pathway flux distribution, and metabolic balance to achieve high CO2 fixation efficiency. By carefully tuning these parameters, the complex pathway system operates efficiently without requiring overly complicated control mechanisms
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 E. coli strain achieves a high yield of malic acid (39 g/L) with a CO2 fixation rate higher than most autotrophic microorganisms, effectively addressing greenhouse gas issues and providing a new method for malic acid production.
Implementation Method 1
The engineered strains can grow with CO2 as the sole carbon source and produce L-malic acid through the Calvin cycle
Implementation Method 2
produce L-malic acid through the Calvin cycle and reductive TCA cycle
Implementation Method 3
allowing the bacteria to produce malic acid efficiently through fermentation
Data Source
AI summary
The disclosure discloses construction and application of an engineered strain of E. coli for producing malic acid by fixing CO2, and belongs to the field of fermentation. The engineered strain is obtained by performing genetic engineering transformation on Escherichia coli MG1655; the genetic engineering transformation includes knocking out a fumarate reductase gene, a fumarase gene, a lactate dehydrogenase gene and an alcohol dehydrogenase gene and freely overexpressing a formate dehydrogenase, an acetyl coenzyme A synthetase, an acylated acetaldehyde dehydrogenase, a formaldehyde lyase, a dihydroxyacetone kinase, a malic enzyme and a phosphite oxidoreductase to obtain a strain GH0407. The strain is used for producing malic acid by fermentation, anaerobic fermentation is performed for 72 hours with CO2 and glucose as a co-substrate, the production of malic acid reaches 39 g/L, the yield is 1.53 mol/mol, and accumulation of malic acid in the original strain is not achieved.