Genetically Modified Yeast Succinate Production
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Solution Overview
Problem
Current biological methods for succinate production using bacteria face challenges such as acidic environments that hinder bacterial performance, leading to economic inefficiencies, while yeast-based methods struggle with pathway engineering and low yields for industrial-scale succinate production.
Innovation Solution
Genetically modified yeast cells with an active succinate fermentation pathway from phosphoenolpyruvate or pyruvate to succinate, incorporating enzymes such as pyruvate carboxylase, phosphoenolpyruvate carboxylase, malate dehydrogenase, fumarase, and succinate exporter genes, optimized for robustness and high yields under low pH conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bacterial fermentation is used for succinate production, then production efficiency is improved, but performance deteriorates under acidic conditions leading to economic inefficiency
Solution Approach 1:
The patent changes the host organism parameter from bacteria to yeast, which inherently tolerate acidic conditions better. This parameter change allows the system to maintain high succinate production efficiency while reliably operating under the acidic pH conditions (pH 3-5) that are economically optimal for organic acid production.
Solution Approach 2:
The patent employs yeast cells that can be easily cultivated and replaced, serving as a disposable biocatalyst system. The yeast can be grown in simple media and used for fermentation, then replaced without complex recovery processes, making the system economically viable despite the need for continuous operation under harsh acidic conditions.
2Reliability
If yeast are used for organic acid production, then advantages over bacteria are achieved, but pathway engineering difficulty and low yields occur
Solution Approach 1:
The patent segments the succinate production pathway into discrete enzymatic steps and introduces them individually into yeast using targeted gene knockout and overexpression strategies. By systematically modifying specific genes (e.g., deleting competing pathways like alcohol dehydrogenase and overexpressing succinate pathway enzymes), the complex engineering challenge is broken down into manageable segments that can be optimized independently.
Solution Approach 2:
The patent changes metabolic flux parameters by adjusting enzyme expression levels and blocking alternative pathways. Through genetic modification to increase flux through the succinate pathway and decrease flux through competing pathways, the system achieves high yields despite the inherent complexity of engineering eukaryotic metabolism.
3Reliability
If buffering is applied to maintain higher pH, then bacterial survival is improved, but product recovery becomes more difficult and expensive
Solution Approach 1:
Instead of buffering to maintain high pH for bacterial survival, the patent inverts the approach by using yeast that naturally thrive in acidic conditions. This allows the fermentation to proceed at low pH without buffering, making the product recovery process simpler and more economical while maintaining reliable organism performance.
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 genetically modified yeast cells achieve enhanced succinate production efficiency and cost-effectiveness by maintaining performance under acidic conditions, overcoming previous limitations in yeast-based succinate production.
Implementation Method 1
The active succinate fermentation pathway includes at least the following reactions 1) conversion of pyruvate and/or phosphoenolpyruvate to oxaloacetate
Implementation Method 2
2) conversion of oxaloacetate to malate
Implementation Method 3
3) conversion of malate to fumarate
Implementation Method 4
4) conversion of fumarate to succinate
Implementation Method 5
The pathway also includes export of succinate from inside the cell to the extracellular environment
Implementation Method 6
There has been increasing interest in recent years around the use of yeast to ferment sugars to organic acids
Data Source
AI summary
The present application provides genetically modified yeast cell comprising an active succinate fermentation pathway, as well as methods of using these cells to produce succinate.