Modified Microorganisms for Organic Acid Production
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Solution Overview
Problem
Current methods for producing industrially useful chemicals like 3-hydroxypropionic acid face challenges due to toxicity to microbes and reliance on food-based carbon sources, necessitating the development of microorganisms with increased tolerance and non-food-based feedstock utilization.
Innovation Solution
Genetically modified organic acid-tolerant microorganisms, such as cyanobacteria, with reduced AcsA activity or its homologs, and expression of enzymes like malonyl-CoA reductase and lactate dehydrogenase to enhance production of organic acids like 3-hydroxypropionic acid and lactic acid, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional microorganisms are used to produce organic acids, then production cost is reduced, but microbial tolerance to organic acids is insufficient leading to low yields
Solution Approach 1:
The patent applies parameter changes by modifying the AcsA enzyme's biochemical properties through site-directed mutagenesis. Specific amino acid substitutions (e.g., E173Q, E173A, E173K) alter the enzyme's kinetic parameters, reducing its affinity for organic acid substrates while maintaining catalytic activity for acetate activation. This parameter modification allows the microorganism to tolerate higher organic acid concentrations without compromising acetate metabolism, thereby increasing organic acid production yield.
2Productivity
If heterotrophic microorganisms are used for chemical production, then chemical output is increased, but dependence on food-based carbon sources increases
Solution Approach 1:
The patent implements self-service by enabling cyanobacteria to utilize CO2 and light energy for organic acid production through engineered metabolic pathways. The modified microorganisms possess endogenous capabilities to fix carbon from inorganic sources and convert it to organic acids (acetate, 3HP, lactic acid) using photosynthetically derived energy, eliminating dependence on external organic carbon sources and achieving self-sufficient production.
Solution Approach 2:
The patent applies universality by designing a dual-function system where cyanobacteria simultaneously perform photosynthesis and organic acid production. The engineered pathways allow the same organism to function both as a photosynthetic carbon fixer and as a fermentative organic acid producer, integrating previously separate functions into a single versatile platform that can operate under various carbon source conditions.
3Object-affected harmful factors
If AcsA activity is maintained at normal levels, then acetate metabolism is efficient, but organic acid tolerance remains low
Solution Approach 1:
The patent applies local quality by creating spatial and functional differentiation in AcsA enzyme populations within the cell. Through partial knockdown strategies and expression of mutant variants with distinct kinetic properties, the system maintains wild-type AcsA activity for efficient acetate metabolism while simultaneously expressing modified AcsA variants that provide organic acid tolerance. This local functional differentiation allows both contradictory requirements to be satisfied in different cellular contexts.
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 microorganisms exhibit increased tolerance to organic acids, allowing for higher yields and production of industrially valuable chemicals like 3-hydroxypropionic acid and lactic acid, utilizing CO2 and light energy without competing for food-based carbon sources.
Implementation Method 1
These microorganisms can produce chemical products from CO2 and light energy without relying on consumption of higher-value carbon sources
Implementation Method 2
expression of enzymes like malonyl-CoA reductase and lactate dehydrogenase to enhance production of organic acids like 3-hydroxypropionic acid and lactic acid
Data Source
AI summary
Organic acid-producing microorganisms and methods of using same. The organic acid-producing microorganisms comprise modifications that reduce or ablate AcsA activity or AcsA homolog activity. The modifications increase tolerance of the microorganisms to such organic acids as 3-hydroxypropionic acid, acrylic acid, propionic acid, lactic acid, and others. Further modifications to the microorganisms increase production of such organic acids as 3-hydroxypropionic acid, lactate, and others. Methods of producing such organic acids as 3-hydroxypropionic acid, lactate, and others with the modified microorganisms are provided. Methods of using acsA or homologs thereof as counter-selectable markers are also provided.