URE2 Mutant Yeast Thiol Release Mechanism
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Solution Overview
Problem
Current yeast strains used in fermentation vary significantly in their ability to release aromatic volatile thiols, which are crucial for the aroma of wines and other fermented beverages, and the genetic mechanisms behind this variability are not well understood, limiting the development of strains with optimized thiol release capabilities.
Innovation Solution
The use of URE2 mutant yeasts with a loss-of-function mutation in the URE2 gene, which enhances the release of aromatic volatile thiols by disrupting nitrogen catabolite repression and activating the IRC7 enzyme, leading to increased production of specific thiol enantiomers like 3-mercaptohexanol, thereby modifying the sensory perception of wine aromas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional yeast strains are used for fermentation, then the fermentation process is straightforward, but the release of aromatic volatile thiols is insufficient and inconsistent
Solution Approach 1:
The invention extracts and isolates the specific genetic mechanism (URE2 gene and IRC7 enzyme) responsible for thiol release from the complex yeast genome. By identifying and manipulating this specific pathway, the patent enables targeted enhancement of thiol release without needing to understand or control the entire genetic system, thus resolving the contradiction between improving thiol quantity and managing genetic complexity.
Solution Approach 2:
The invention changes the genetic parameter of the yeast strain by introducing loss-of-function mutations in the URE2 gene. This parameter change (genetic modification) directly increases the release of aromatic volatile thiols, transforming conventional yeast into strains with enhanced aromatic capabilities while maintaining straightforward fermentation processes.
2Quantity of substance
If yeast strains with high thiol release capability are selected through screening, then aromatic production is improved, but the variability among strains remains significant and mechanisms are unclear
Solution Approach 1:
The invention establishes a feedback mechanism by identifying the specific genetic pathway (URE2-IRC7) that controls thiol release. This knowledge creates a reliable basis for strain selection and development, allowing producers to consistently achieve high thiol release by using strains with confirmed mutations in this pathway, rather than relying on variable screening results.
Solution Approach 2:
By systematically changing the URE2 gene parameter (introducing loss-of-function mutations), the invention creates yeast strains with reliably enhanced thiol release. This controlled parameter change approach replaces the variable outcomes of traditional strain screening with consistent, mechanism-based improvement.
3Quantity of substance
If traditional strain screening and breeding programs are conducted, then new strains with higher thiol liberation are obtained, but the genetic determinism and molecular mechanisms remain unclear
Solution Approach 1:
The invention extracts the specific genetic mechanism (URE2 gene regulating IRC7 enzyme) from the complex background of yeast genetics. This extraction reveals the molecular mechanism behind thiol liberation, transforming the black box of traditional breeding into an understood and controllable pathway, thereby preventing loss of genetic mechanism information.
Solution Approach 2:
The invention identifies IRC7 enzyme as an intermediary between the URE2 gene and the final thiol products. This intermediary role clarifies the molecular mechanism: URE2 regulates IRC7, which catalyzes the conversion of precursors to volatile thiols. This intermediary identification fills the information gap left by traditional breeding programs.
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 URE2 mutant yeasts increase the release of volatile thiols by threefold, significantly altering the 3MH enantiomer balance and intensifying grapefruit overtones, allowing for the production of wines with consistent and definable aromatic profiles.
Implementation Method 1
The invention relates to the use of URE2 mutant yeasts for increasing the release of aromatic volatile thiols by yeast during fermentation
Implementation Method 2
The transformation of such precursors in volatile thiols is achieved by yeast metabolism and involves a carbon-sulfur β-lyase activity
Data Source
Figure 1
Figure 2A~2B
AI summary
Use of a URE2 mutant yeast having a loss-of-function mutation in the URE2 gene for increasing the release of aromatic volatile thiol by yeast during fermentation.