Organic Acid-Tolerant Microorganisms for 3HP Production
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Solution Overview
Problem
Current methods for producing industrially useful chemicals, such as 3-hydroxypropionic acid, face challenges due to toxicity to microorganisms and reliance on food-based carbon sources, necessitating the development of microorganisms with increased tolerance to these chemicals and the ability to use non-food-based feedstocks.
Innovation Solution
Genetically modified cyanobacteria with reduced or ablated AcsA activity, combined with recombinant nucleic acids for overexpressing 3HP pathway enzymes, enhance tolerance to organic acids like 3-hydroxypropionic acid, acrylic acid, and propionic acid, allowing for higher production yields and tolerance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microorganisms are used to produce organic acids like 3-hydroxypropionic acid, then chemical production from renewable resources is achieved, but the microorganisms suffer from toxicity and reduced viability
Solution Approach 1:
The patent applies parameter changes by modifying the intracellular environment of the microorganism through genetic engineering. Specifically, it overexpresses compatible solutes (such as ectoine, hydroxyectoine, and glycine betaine) and alters osmolyte composition to change the physiological parameters inside the cell. This creates a more tolerant intracellular environment that can withstand higher concentrations of toxic organic acids, thereby resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent introduces compatible solutes as intermediary substances that mediate between the toxic organic acids and the microorganism's cellular components. These solutes act as protective intermediaries that do not interfere with cellular metabolism but provide shielding against acid toxicity. The overexpression of solute synthesis genes (ectABC, betB) creates these intermediary protective agents, allowing the microorganism to maintain viability while producing organic acids.
2Productivity
If food-based carbon sources are used for chemical production, then microbial growth and product formation are supported, but dependence on food commodities increases
Solution Approach 1:
The patent applies universality by engineering the microorganism to perform multiple functions: it can now utilize both traditional food-based carbon sources (glucose, sucrose) and non-food-based renewable resources (lignocellulosic biomass, agricultural residues). The genetic modifications enable the microorganism to process diverse carbon sources through expanded metabolic pathways, making the production system versatile and independent of food commodity availability.
Solution Approach 2:
The patent segments the carbon source utilization into separate metabolic pathways. It introduces or enhances specific enzymatic pathways (such as cellulase, hemicellulase, and lignin-degrading enzyme systems) that can independently process different types of carbon sources. This segmentation allows the microorganism to selectively utilize appropriate carbon sources based on availability, reducing dependence on food-based commodities while maintaining productivity.
3Productivity
If tolerance to organic acids is increased through genetic modification, then production yields can be raised, but the complexity of the production system increases
Solution Approach 1:
The patent merges multiple tolerance mechanisms into a single integrated genetic modification strategy. Instead of implementing separate complex systems for different stress responses, it combines the overexpression of compatible solute synthesis genes (ectABC, betB) with the organic acid production pathway. This merging creates a unified tolerance mechanism that handles multiple aspects of acid stress (osmotic stress, protein denaturation, membrane disruption) through a coordinated genetic approach, reducing overall system complexity.
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 significantly increased tolerance to these organic acids, enabling higher production yields and the use of CO2 and light energy as carbon sources, reducing dependence on food-based commodities.
Implementation Method 1
These microorganisms can produce chemical products from CO2 and light energy without relying on consumption of higher-value carbon sources
Data Source
AI summary
Organic acid-tolerant microorganisms and methods of using same. The organic acid-tolerant 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 (3HP), acrylic acid, and propionic acid. Further modifications to the microorganisms such as increasing expression of malonyl-CoA reductase and/or acetyl-CoA carboxylase provide or increase the ability of the microorganisms to produce 3HP. Methods of generating an organic acid with the modified microorganisms are provided. Methods of using acsA or homologs thereof as counter-selectable markers include replacing acsA or homologs thereof in cells with genes of interest and selecting for the cells comprising the genes of interest with amounts of organic acids effective to inhibit growth of cells harboring acsA or the homologs.