Researchers invent new method to create hybrid yeast strains

UW-Madison researchers have developed a new method for creating hybrid yeast strains for use in commercial fermentation and brewing.

An info sheet from the Wisconsin Alumni Research Foundation shows interspecies yeast hybrids are needed to produce certain fermented beverages. For example, the globally popular lager beer is made with hybrids of Saccharomyces cerevisiae and Saccharomyces eubayanus — two common yeast species.

The current process for creating improved hybrids is “cumbersome,” according to WARF, as it can require genetic modification. And that has led some to question their safety.

To improve on that process, researchers have developed a process called Hybrid Production, or HyPr. It doesn’t require any modification of the nuclear genome, which WARF lists as a benefit.

The info sheet says the new method is “simple, more robust and efficient than known techniques.” And it could be applied to many yeast strains important to multiple industries, including beverages as well as biofuels.

It’s noted that demand is growing for “locally sourced” yeast strains, especially for the craft brewing industry. WARF is seeking commercial partners to develop this method, which could be used by a company to create designer yeast hybrids for brewers.

HyPr has been used to produce strains of yeast with extra sets of chromosomes, for use in lagers, Belgian ale and cider.

The lead inventor is Chris Hittinger, an assistant professor of genetics at UW-Madison. He’s published a number of studies on the genetics of yeast and fungi.  

Hittinger is also involved with developing wild strains of yeast, discovered in both Wisconsin and the Chicago area.

Three new strains of a yeast called Saccharomyces eubayanus were discovered in Wisconsin in 2012. They were isolated from an old beech tree at Sheboygan Indian Mound Park. According to another info sheet from WARF, they are the first Saccharomyces eubayanus strains found outside of Argentina, and also the first strains available for commercial licensing.

More recently, researchers at UW-Madison identified new strains of three more yeast species in 2014: Saccharomyces cerevisiae, Torulaspora delbrueckii and Hanseniaspora uvarum.

These strains were discovered in the Chicago area, from samples of soil, tree bark and fruit submitted by citizen volunteers.

These new strains could have applications in the craft brewing industries, and WARF is looking for commercial partners to develop all of them.

See more on the new method:

See details on the Wisconsin-sourced yeast:

See details on the yeast from the Chicago area: