Adaptive Evolution of Saccharomyces cerevisiae for Wine Quality
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Solution Overview
Problem
Current winemaking techniques rely on yeast strains of the genus Saccharomyces, particularly S. cerevisiae, which produce high levels of ethanol and acetic acid, leading to wines with undesirable characteristics, and there is a need for yeast strains that can optimize wine-making properties such as higher glycerol production and lower acetic acid production without being genetically modified.
Innovation Solution
A method for obtaining non-genetically modified yeast strains of Saccharomyces cerevisiae with optimized wine-making properties by growing the initial strain in a culture medium with increasing concentrations of 2-aminoethyl-L-cysteine (AEC) for several weeks, allowing for adaptive evolution and selection of mutants that tolerate AEC, resulting in strains with enhanced glycerol production and reduced ethanol and acetic acid production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional yeast strains (S. cerevisiae) are used for winemaking, then fermentation efficiency is high and ethanol production is high, but acetic acid production increases and glycerol production is insufficient
Solution Approach 1:
The patent applies parameter changes by exposing yeast to increasing concentrations of 2-AEC (a toxic lysine analogue) over multiple generations. This selective pressure induces mutations that alter metabolic parameters, specifically increasing glycerol production and decreasing acetic acid production while maintaining fermentation efficiency. The gradual increase in AEC concentration from initial low levels to final high levels drives the metabolic transformation.
Solution Approach 2:
The patent converts the harmful effect of 2-AEC (toxicity to yeast) into a beneficial outcome. By using AEC as a selective agent, the patent inadvertently selects for yeast mutants that have altered metabolism producing less acetic acid and more glycerol. The harmful substance AEC becomes a tool for improving wine quality by selecting desirable metabolic phenotypes.
2Quantity of substance
If traditional yeast strains are used, then ethanol production is high, but the wine organoleptic balance is compromised
Solution Approach 1:
The patent changes metabolic parameters through adaptive evolution in the presence of AEC. The selected mutants maintain high ethanol production capability while simultaneously reducing acetic acid and increasing glycerol, thereby improving organoleptic balance. The metabolic flux is redirected without sacrificing fermentative performance.
3Reliability
If yeast strains are selected for stress tolerance, then adaptation to extreme temperatures is improved, but aromatic production may be reduced
Solution Approach 1:
The patent changes the selection parameter from stress tolerance to AEC tolerance, which specifically targets metabolic pathway alterations. This selective pressure favors mutants with modified carbohydrate metabolism that produce more glycerol and less acetic acid, without necessarily compromising stress tolerance or aromatic production capabilities.
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 resulting yeast strains demonstrate improved wine-making properties, including increased glycerol production, decreased acetic acid production, and reduced ethanol levels, thereby enhancing the quality and organoleptic characteristics of wines.
Implementation Method 1
The bulk of the metabolism of the sugars present in the must is dedicated to the production of ethanol through fermentation
Implementation Method 2
the high amount of glucose and fructose in the must produces a hyperosmotic stress that is compensated with the production of the compatible osmolyte glycerol
Implementation Method 3
growing the initial strain in a culture medium with increasing concentrations of 2-aminoethyl-L-cysteine (AEC) for several weeks, allowing for adaptive evolution and selection of mutants that tolerate AEC
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3D
AI summary
The present invention relates to a method for producing improved strains of Saccharomyces cerevisiae with optimised wine-making properties, which comprises preparing at least one culture, wherein an initial strain of S. cerevisiae is in contact with at least 10 mg/l of 2-aminoethyl-L-cysteine in a culture medium and is grown for at least five weeks; and isolating individual mutants of the S. cerevisiae strain with optimised wine-making properties once that time has elapsed. The invention also relates to improved strains obtained using the method and to uses of same in the alcoholic fermentation of vegetable substrates.