Acid-Resistant Yeast for Lactic Acid Production
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Solution Overview
Problem
Traditional lactic acid production using lactic acid bacteria is inefficient due to the need for neutral pH maintenance, high nutrient costs, and the generation of neutralization salts, which increases production costs and reduces process efficiency.
Innovation Solution
Development of a recombinant acid-resistant yeast strain with reduced lactate consumption and enhanced lactic acid production ability by deleting genes involved in lactate to pyruvate conversion and introducing a lactate dehydrogenase gene, allowing for high-yield lactic acid production at acidic pH without neutralizing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lactic acid bacteria are used for lactic acid production, then lactic acid can be produced through fermentation, but neutral pH maintenance is required which increases production costs and reduces process efficiency
Solution Approach 1:
The patent changes the pH parameter from neutral (6-8) to acidic (below 5.6), allowing the use of acid-resistant yeast instead of lactic acid bacteria. This parameter change eliminates the need for neutralizing agents and simplifies the fermentation process while maintaining high lactic acid production efficiency.
Solution Approach 2:
The patent uses acid-resistant yeast that can be cultured in inexpensive media without requiring costly neutralizing agents like CaCO3 or NH3. The yeast cells can be easily separated after fermentation, making the process more economically viable and reducing manufacturing complexity.
2Productivity
If lactic acid bacteria are used for lactic acid production, then lactic acid can be produced, but high nutrient costs are incurred
Solution Approach 1:
The patent employs acid-resistant yeast that can grow and produce lactic acid in inexpensive media compositions. The yeast does not require the rich nutrient conditions needed by lactic acid bacteria, significantly reducing the quantity and cost of nutrients consumed while maintaining high lactic acid yield.
3Productivity
If lactic acid bacteria are used for lactic acid production, then lactic acid can be produced, but neutralization salts are generated which increases production costs
Solution Approach 1:
The patent converts the harmful effect of acid accumulation during fermentation into a beneficial feature by using acid-resistant yeast that thrives in acidic conditions. This eliminates the need for neutralization steps that generate waste salts, transforming what was previously a problem (acidic environment) into an advantage (no neutralization needed, no salt waste).
Solution Approach 2:
The patent eliminates the neutralization step entirely, discarding the practice of adding bases to maintain pH. The acid-resistant yeast naturally tolerates and produces acid without requiring pH adjustment, thereby avoiding the generation and subsequent disposal or recovery of neutralization salts like CaSO4.
4Ease of manufacture
If acid-resistant yeast is used for lactic acid production, then neutralizing agents are not needed, but ethanol production occurs which reduces lactic acid purity
Solution Approach 1:
The patent extracts or removes the ethanol production pathway from the acid-resistant yeast through genetic modification. By deleting genes involved in ethanol metabolism (such as ADH and PDC genes), the yeast is forced to convert pyruvate exclusively to lactic acid, eliminating ethanol as a byproduct and ensuring high lactic acid purity while maintaining process simplicity.
5Productivity
If traditional fermentation is used, then lactic acid can be produced, but pH must be maintained at neutral range which requires additional processes
Solution Approach 1:
The patent fundamentally changes the pH parameter from neutral (6-8) to acidic (below 5.6), which eliminates the need for complex pH control systems. The acid-resistant yeast naturally maintains acidic pH conditions without requiring addition of neutralizing agents, thereby simplifying the device complexity and process control requirements.
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 recombinant yeast strain significantly increases lactic acid yield while inhibiting ethanol production, achieving high lactic acid production efficiency and reducing production costs by operating at acidic pH without the need for neutralizing agents.
Implementation Method 1
introducing a lactate dehydrogenase gene
Implementation Method 2
conducting fermentation while maintaining a neutral pH
Data Source
AI summary
Disclosed is a method of producing lactic acid using a recombinant acid-resistant yeast with inhibited lactate metabolism and alcohol production. More specifically, disclosed are a recombinant acid-resistant yeast in which lactate consumption reaction is reduced and which is imparted with lactic-acid-producing ability to thereby exhibit improved lactic-acid-producing ability and reduced ethanol production, and a method of producing lactic acid using the same.