The great taste of Suntory beer is the result of fermenting carefully selected ingredients with Suntory's own original yeasts. However, there are still many parts of the yeast fermentation process that science has yet to explain.
To help fill in some of these gaps, Suntory set out to map the genome that serves as a blueprint for beer yeast—and succeeded in being the first in the world to do so. Just as sequencing the human genome helps us prevent diseases through genetic diagnosis and customized medical solutions, mapping the genome of beer yeast genome allows us to comprehensively analyze gene expression analysis in fermentation yeast to find out which genes work, how well they work, when they are activated, and the kinds of flavors they produce. Thanks to this groundbreaking work, we are now able to select the ideal yeasts to create the tastes we want while using genetic diagnostics to track the quality of yeasts in our breweries.
Lagers are by far the most common type of beer. More than 90% of the beer brewed in the world and over 99% in Japan is lager. Lager beers are produced by bottom-fermenting yeast. Because of its ubiquitous popularity, Suntory chose to sequence the genome of the bottom-fermenting Saccharomyces pastorianus Weihenstephan Nr.34.
Note: Here, "beer yeast" refers to bottom-fermenting yeast only.
A DNA microarray is a chip that has a collection of target gene fragments attached to a surface several centimeters in size (see photo at right). It allows scientists to simultaneously analyze the expression of extremely large numbers of genes. Using information from the sequenced genome, Suntory developed a DNA microarray that can monitor the expression of all 12,000 or so beer yeast genes.
The use of this microarray allows us to uncover the relationships between beer yeast genes and the resulting beer flavors. Analyzing with the chip has also allowed us to classify beer yeasts and examine changes in their genome structure through genetic diagnostic techniques.
Genetic diagnosis allows us to select the best yeast for producing delicious beers. We can also determine the ideal fermentation conditions for these yeasts by identifying the genes involved in brewing and their functions. As an example, a beer yeast–specific gene (non-Sc-type SSU1) has been found to contribute substantially to the production of sulfite, which is a natural flavor stabilizers.
Genome sequencing tells us that beer yeast is an unstable organism at the genetic level. Changes in genome structure at breweries can delay fermentation and lead to undesirable flavors and tastes.
To address this concern, Suntory created a way to monitor structural changes in the yeast genome using a DNA microarray. We also developed a method of detecting these structural changes even faster and more easily than with the DNA chip, and used it to set up a system to monitor these changes at our breweries. These "health checkups" for yeast allow us to create better conditions for our yeast, which in turn creates a more delicious, reliable product for our customers.