2 of acetate ester production (isoamyl acetate/alcohol ~AATase activity). (B) Mating and reproduction of segregants (offspring) with CO range2-inhibition of AATase activity followed by selection of a pool of segregants with an excellent profile of acetate ester production. (C) Whole-genome sequence analysis of the best pool and bioinformatic analysis to identify QTLs responsible for the trait. (D) Schematic representation of (Bulk) RHA used to identify the causative gene at QTL 2. (E) Graphical overview of the 2 strategies and different plasmids used for CRISPR/Cas9-mediated MDS3 allelic exchange. Author: Applied and environmental microbiology (2022). DOI: 10.1128/aem.00814-22″ width=”800″ height=”530″/>

Overview of the experimental methods used in this study. (A) Laboratory determination of CO2 overpressure inhibition of acetate ester production (isoamyl acetate/alcohol ~AATase activity). (B) Mating and breeding of segregants (offspring) with CO range2– inhibition of AATase activity followed by selection of a pool of segregants with the highest acetate production profile. (C) Whole-genome sequencing analysis of the best pool and bioinformatic analysis to identify QTLs responsible for the trait. (D) Schematic representation of (Bulk) RHA used to identify the causative gene at QTL 2. (E) Graphical overview of the 2 strategies and different plasmids used for CRISPR/Cas9-mediated MDS3 allelic exchange. credit: Applied and environmental microbiology (2022). DOI: 10.1128/aem.00814-22

Belgian researchers have improved the taste of modern beer by identifying and engineering a gene responsible for much of the taste of beer and some other alcoholic beverages. The study appears in Applied and environmental microbiology.


For centuries, beer was brewed in open horizontal vats. But in the 1970s, the industry switched to using large, closed containers that are much easier to fill, empty, and clean, allowing larger volumes to be brewed and lower costs. However, these modern methods produced lower quality beer due to insufficient flavor.

During fermentation, yeast converts 50 percent of the sugar in the mash to ethanol and the remaining 50 percent to carbon dioxide. The problem: Carbon dioxide creates pressure in these sealed vessels, dulling the taste.

Johan Tevelein, Ph.D., Emeritus Professor of Molecular Cell Biology at Catholic University, and his team were pioneers in identification technology genes is responsible for the commercially important properties of yeast. They applied this technology to identify the gene(s) responsible for beer flavor by screening a large number of yeast strains to determine which best retain flavor under pressure.

They focused on the banana flavor gene “because it’s one of the most important flavors present in beer as well as other alcoholic beverages,” said Theveline, who is also the founder of NovelYeast, which collaborates with other companies in industrial biotechnology. .

“To our surprise, we identified a single mutation in the MDS3 gene, which encodes a regulator apparently involved in the production of isoamyl acetate, the source of the banana flavor responsible for most of the stress tolerance in this specific yeast strain. ” – said Theveline.

Theveline and his collaborators then used CRISPR/Cas9, a gene-editing technology, to create this mutation in other brewers, which similarly improved their tolerance of carbon dioxide pressure, providing a fuller flavor. “This demonstrated the scientific significance of our findings and theirs commercial potential” – said Theveline.

“The mutation is the first insight into the mechanism by which high carbon dioxide pressure can be disrupted beer aroma production,” said Theveline, who noted that the MDS3 protein is likely a component of an important regulatory pathway that may play a role in carbon dioxide inhibition of banana aroma production, adding, “how this happens is not clear.”

The technology has also been successful in identifying genetic elements important to roses fragrance yeast production alcoholic beveragesas well as other commercially important traits such as glycerol production and heat resistance.


Researchers identify yeast genes underlying rose and honey flavors in beer and wine


Additional information:
Ben Souffriau et al., Polygenic Analysis of Carbon Dioxide Tolerance, Inhibition of Isoamyl Acetate ‘Banana’ Flavor Production in Yeast Identifies MDS3 as Major Causative Gene, Applied and environmental microbiology (2022). DOI: 10.1128/aem.00814-22

Citation: Microbiologists make beer taste better (2022, October 4) Retrieved October 4, 2022, from https://phys.org/news/2022-10-microbiologists-beer.html

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