Recombinant Acid-Resistant Yeast for Lactic Acid Production
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Solution Overview
Problem
Current lactic acid production using yeast is inefficient due to high glycerol production, which acts as an impurity, and requires neutralization processes that increase costs and reduce yield, while maintaining high acid resistance and fermentation performance similar to lactic acid bacteria.
Innovation Solution
A recombinant acid-resistant yeast strain is developed by deleting genes involved in glycerol production and introducing a gene encoding lactate dehydrogenase, specifically deleting the GPD1 gene and introducing the LDH gene into the acid-resistant yeast YBC strain, reducing glycerol production and enhancing lactic acid production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional lactic acid bacteria fermentation is used, then lactic acid production is achieved, but neutralization salts are generated in large amounts requiring costly removal processes
Solution Approach 1:
The invention changes the pH parameter from neutral (6-8) to acidic (2-4) by using acid-resistant yeast instead of traditional lactic acid bacteria, eliminating the need for neutralization and subsequent salt removal processes
Solution Approach 2:
The invention extracts and removes the neutralization step from the fermentation process by selecting an acid-resistant organism that can ferment at low pH, thereby eliminating the generation of neutralization salts
2Reliability
If yeast is used for lactic acid production, then acid resistance and reduced nutrient requirements are achieved, but glycerol production increases acting as an impurity
Solution Approach 1:
The invention extracts and removes the harmful glycerol byproduct from the fermentation process by deleting the GPD1 gene responsible for glycerol production, while retaining the beneficial acid-resistant properties of yeast
Solution Approach 2:
The invention changes the metabolic pathway parameters by introducing heterologous LDH genes to redirect carbon flux from glycerol production to lactic acid production, altering the fermentation outcome
3Object-generated harmful factors
If GPD1 gene is deleted to reduce glycerol production, then glycerol impurity is reduced, but lactic acid production capability must be maintained
Solution Approach 1:
The invention introduces multiple LDH gene copies (three copies in the embodiment) to compensate for the loss of metabolic flexibility from GPD1 deletion, ensuring sufficient lactic acid production capacity while maintaining reduced glycerol levels
Solution Approach 2:
The invention changes the enzymatic parameters by introducing heterologous LDH genes with high specific activity to compensate for the deleted GPD1 pathway, redirecting metabolic flux toward lactic acid accumulation
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 maintains high lactic acid production while significantly reducing glycerol production, improving the conversion yield of lactic acid to lactide and lowering production costs by eliminating the need for neutralization processes.
Implementation Method 1
a gene encoding an enzyme that converts dihydroxyacetone phosphate to glycerol-3-phosphate is deleted or attenuated
Implementation Method 2
a gene encoding lactate dehydrogenase is introduced into the acid-resistant yeast YBC strain
Implementation Method 3
PLA is produced through fermentation
Data Source
AI summary
Disclosed are a recombinant acid-resistant yeast having lactic acid-producing ability and suppressed glycerol production and a method of preparing lactic acid using the same. More particularly, disclosed are a recombinant acid-resistant yeast into which a gene involved in lactic acid production is introduced and in which a gene involved in glycerol production is deleted or attenuated, and a method of preparing lactic acid using the same. When producing lactic acid using the recombinant acid-resistant yeast, the production of lactic acid is maintained while the production of glycerol is reduced, so crosslinking by glycerol can be suppressed in the oligomerization reaction for conversion to lactide, and thus the conversion yield of lactic acid to lactide can be increased.