Engineered Yeast Beta-Lyase for Volatile Thiol Fermentation
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Solution Overview
Problem
Existing yeast strains are inefficient in producing desired volatile thiols like 3-mercaptohexan-1-ol, 3-mercaptohexyl acetate, and 4-methyl-4-mercaptopentan-2-one during fermentation, while concurrently producing undesired compounds such as indoles, limiting the production of tropical fruit flavors in beverages.
Innovation Solution
Genetically modified yeast cells engineered to express a beta-lyase enzyme with specific mutations, such as H463F, to enhance the production of desired volatile thiols and reduce the production of indoles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing yeast strains are used for fermentation, then the fermentation process can proceed normally, but the production of desired volatile thiols is inefficient and undesired compounds like indoles are produced
Solution Approach 1:
The patent applies parameter changes by introducing a mutated beta-lyase enzyme with altered amino acid sequence (specifically H463F mutation) to change the catalytic properties of the enzyme. This mutation modifies the enzyme's substrate specificity and catalytic efficiency, enabling it to preferentially convert precursors into desired volatile thiols while reducing formation of undesired indole compounds. The parameter change is implemented at the molecular level through genetic engineering of the enzyme's primary structure.
Solution Approach 2:
The patent replaces the natural yeast metabolic system with a genetically engineered system that expresses a modified beta-lyase enzyme. This substitution changes the biochemical mechanism of thiol production from the native yeast pathway to an engineered enzymatic pathway, achieving superior selectivity and efficiency in producing desired volatile thiols while minimizing harmful byproducts.
2Productivity
If genetically modified yeast cells express beta-lyase enzyme, then production of desired volatile thiols increases, but the complexity of genetic engineering and enzyme optimization is required
Solution Approach 1:
The patent applies segmentation by focusing the genetic engineering effort on a specific critical region of the beta-lyase enzyme (position 463). Instead of attempting comprehensive optimization of the entire enzyme sequence, the invention identifies and modifies a single key amino acid position that has the most significant impact on substrate specificity and product distribution. This segmented approach to enzyme optimization reduces the complexity of genetic engineering while achieving the desired improvement in volatile thiol production.
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 yeast cells significantly increase the production of 3-mercaptohexan-1-ol, 3-mercaptohexyl acetate, and 4-methyl-4-mercaptopentan-2-one, while reducing indole levels, thereby enhancing the tropical fruit flavors in fermented beverages.
Implementation Method 1
comprising a heterologous gene encoding an enzyme with beta-lyase activity
Implementation Method 2
contacting any of the modified cells described herein with a medium comprising at least one fermentable sugar, wherein the contacting is performed during at least a first fermentation process
Data Source
AI summary
Provided herein are genetically modified yeast cells that recombinantly expresses a gene encoding a mutant beta-lyase. Also provided are methods of producing fermented products and methods of producing ethanol.