April 10, 2014
Brewer’s Yeast Used In European Lagers Has Its Roots In South America
Brett Smith for redOrbit.com - Your Universe Online
The Saccharomyces pastorianus yeast is an essential ingredient that helped to make European lager beers over the past few hundred years and a new study in the journal Molecular Ecology has revealed that this yeast actually has its roots in South America.
The new study confirms that a “traveling” parent of the brewing yeast, called Saccharomyces eubayanus, discovered in 2011, is indeed from South America – more specifically from Patagonia. The study team said this cold-loving yeast made its way to the caves and brewing cellars of Europe about 500 years ago.
"This yeast really is native to Patagonia," said study author Chris Hittinger, a University of Wisconsin-Madison researcher who was part of the team that discovered S. eubayanus three years ago. "We found two major populations that seem to be distinct. The trees they're associated with seem to provide everything they need. They're happy there."
For the study, the team carried out considerable field surveys, including some in the Patagonian landscape where the cold-adapted yeast appears quite frequently. In their travels, the researchers also found strains of the Patagonia-derived S. eubayanus near Sheboygan, Wis. There, the yeast appears limited in scope and was most likely accidentally released – just as its ancestor was on the way to Europe and began the creation of cold-brewed lager beer hundreds of years ago, the researchers said.
"If I had to bet, I'd lay money on ski bums or migrating birds" as the mode of transportation to Wisconsin, Hittinger said. "What we think is happening is that well-established, genetically diverse populations are sending migrants around the world. Generally, they're not successful, but occasionally they are."
Like most described yeasts, the Patagonian yeast was able to add traits by genetically combining different species. In the case of the lager yeast, the South American S. eubayanus yeast hybridized with a species known as Saccharomyces cerevisiae. Although rare in nature, industrial fermentation methods allow for even rare hybrids to be recovered, the study team noted.
The researchers said they hoped their study leads to an unlocking of the secrets of fermentation, which is currently used in the production of everything from beer to biofuels.
"Yeasts are important for fermenting processes and biotechnology," said study author David Peris, a UW-Madison researcher. "The value of studying diversity is that you can pull out genes or strains that can be used for a particular industrial process."
In an industrial setting, yeasts are primarily used to break down sugars and produce alcohol – which they release as a byproduct. Currently, four of the seven described Saccharomyces species of yeast are involved in industrial processes.
"The idea," Hittinger said, "is to tap into biodiversity and find the strains that ferment better and those strains, or their genes, can be plugged into industrial processes."
He added that brewers and winemakers have artificially selected for certain hybrids over the decades. Modern technology and genetic engineering could potentially refine industrial fermentation to result in a better conversion of sugar to alcohol, Hittinger said.