Summary
"The common baker's yeast, Saccharomyces cerevisiae, is used in various industrial applications, ranging from the production of fermented beverages like beer and wine, foods including bread and chocolate, bioethanol, enzymes and pharmaceuticals.
S. cerevisiae cells can grow aerobically, using the TCA cycle and electron transport chain to produce around 16 to 18 molecules of ATP (energy) per glucose molecule. However, when glucose concentrations exceed about 1% (w/w), the cells tend to shut down this respiratory mechanism in favour of alcoholic fermentation, even if this metabolic route only yields 2 ATP molecules per glucose consumed. This so-called ""Crabtree effect"" makes it difficult to efficiently cultivate industrial yeasts in large-scale industrial fermenters because maximal biomass yield is only obtained in conditions where glucose concentrations are kept below the critical limit for activation of the Crabtree effect, but high enough to allow maximal growth. Interestingly, however, some S. cerevisiae strains seem to be less sensitive to glucose inhibition of respiration than others, suggesting that certain natural strains harbour specific alleles that make them less subjected to Crabtree repression.
In our ongoing ERC CoG, we have shown that besides limiting efficient biomass formation, the Crabtree effect also decreases the efficiency with which strains can metabolize industrial media. Moreover, we identified an as yet uncharacterised gene, YLR108C, that controls the glucose level at which respiration becomes repressed. Our preliminary results show that swapping natural alleles of YLR108C changes the level of glucose at which the Crabtree repression starts.
In this PoC, we propose to use our findings to generate superior industrial yeasts that combine optimal industrial fermentation performance with more efficient biomass production. To avoid generating GM strains, we will use natural breeding and/or self-cloning techniques."
S. cerevisiae cells can grow aerobically, using the TCA cycle and electron transport chain to produce around 16 to 18 molecules of ATP (energy) per glucose molecule. However, when glucose concentrations exceed about 1% (w/w), the cells tend to shut down this respiratory mechanism in favour of alcoholic fermentation, even if this metabolic route only yields 2 ATP molecules per glucose consumed. This so-called ""Crabtree effect"" makes it difficult to efficiently cultivate industrial yeasts in large-scale industrial fermenters because maximal biomass yield is only obtained in conditions where glucose concentrations are kept below the critical limit for activation of the Crabtree effect, but high enough to allow maximal growth. Interestingly, however, some S. cerevisiae strains seem to be less sensitive to glucose inhibition of respiration than others, suggesting that certain natural strains harbour specific alleles that make them less subjected to Crabtree repression.
In our ongoing ERC CoG, we have shown that besides limiting efficient biomass formation, the Crabtree effect also decreases the efficiency with which strains can metabolize industrial media. Moreover, we identified an as yet uncharacterised gene, YLR108C, that controls the glucose level at which respiration becomes repressed. Our preliminary results show that swapping natural alleles of YLR108C changes the level of glucose at which the Crabtree repression starts.
In this PoC, we propose to use our findings to generate superior industrial yeasts that combine optimal industrial fermentation performance with more efficient biomass production. To avoid generating GM strains, we will use natural breeding and/or self-cloning techniques."
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| Web resources: | https://cordis.europa.eu/project/id/959109 |
| Start date: | 01-01-2021 |
| End date: | 30-06-2022 |
| Total budget - Public funding: | - 150 000,00 Euro |
Cordis data
Original description
"The common baker's yeast, Saccharomyces cerevisiae, is used in various industrial applications, ranging from the production of fermented beverages like beer and wine, foods including bread and chocolate, bioethanol, enzymes and pharmaceuticals.S. cerevisiae cells can grow aerobically, using the TCA cycle and electron transport chain to produce around 16 to 18 molecules of ATP (energy) per glucose molecule. However, when glucose concentrations exceed about 1% (w/w), the cells tend to shut down this respiratory mechanism in favour of alcoholic fermentation, even if this metabolic route only yields 2 ATP molecules per glucose consumed. This so-called ""Crabtree effect"" makes it difficult to efficiently cultivate industrial yeasts in large-scale industrial fermenters because maximal biomass yield is only obtained in conditions where glucose concentrations are kept below the critical limit for activation of the Crabtree effect, but high enough to allow maximal growth. Interestingly, however, some S. cerevisiae strains seem to be less sensitive to glucose inhibition of respiration than others, suggesting that certain natural strains harbour specific alleles that make them less subjected to Crabtree repression.
In our ongoing ERC CoG, we have shown that besides limiting efficient biomass formation, the Crabtree effect also decreases the efficiency with which strains can metabolize industrial media. Moreover, we identified an as yet uncharacterised gene, YLR108C, that controls the glucose level at which respiration becomes repressed. Our preliminary results show that swapping natural alleles of YLR108C changes the level of glucose at which the Crabtree repression starts.
In this PoC, we propose to use our findings to generate superior industrial yeasts that combine optimal industrial fermentation performance with more efficient biomass production. To avoid generating GM strains, we will use natural breeding and/or self-cloning techniques."
Status
CLOSEDCall topic
ERC-2020-POCUpdate Date
27-04-2024
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