Heineken tamed the wild yeast, but Diego Libkind, a scientist from Argentina, found it. He and his colleagues detected the strain growing on trees in the mountains of Patagonia. They tested the strain in 2011 and identified it as the saccharomyces eubayanus species, one of lager yeast's long-lost parents.

"When you look around the world, you see a lot of breweries varying in ingredients, and we love that. But yeast is something different," van Waesberghe said. "It's very difficult, and in this moment, until now, there were three types which you could use to make beer. And we discovered the fourth one."

There are many strains of yeast used to make beer, but they all fall into one of three categories: ale, lager and sour beer, according to Willem van Waesberghe, Heineken's global brewmaster. A category could emerge using wild yeast.

Yeast is essential to making beer, well, beer. Grains such as barley are combined with hops to create a sugary substance called wort. Yeast is then added to the mixture. It eats the sugar and releases carbon dioxide and alcohol.

Heineken is launching a so-called wild lager in October. Named H41, the beer is made with a yeast that has been identified as one of the parents of lager yeast, including the A-yeast that is used to make Heineken.

Hops may be the hot topic in the mainstream beer world these days, but Heineken is featuring a different ingredient for its new line: yeast.

Van Waesberghe learned about Libkind's findings and wondered how it could be applied to beer. Heineken licensed the right to use the yeast in its beer.

It took van Waesberghe two years to create the beer that today is H41, named for the latitude where the yeast was found. He used the same recipe the traditional Heineken uses, only substituting the domestic yeast for the wild one.

But it wasn't that easy. The yeast that most brewers use has already been trained to eat sugars and in turn produce alcohol and carbon dioxide. The wild strain didn't want to do that.

It did not want to produce alcohol, van Waesberghe said. Sometimes when it did, it produced other components van Waesberghe did not want. He tinkered with variables such as air, pressure and temperature until it finally produced a satisfying flavor.

The brew is already available in some European markets. It will make its American debut in October, where it will be available in New York City. Heineken plans to expand it to additional

markets next year.

Advertising yeast may be more difficult in the U.S. than in some European countries. Van Waesberghe said the lack of understanding about yeast's role in the States amazes him. In countries such as Italy, he said, people appreciate yeast and understand its integral role in bread.

"We are on a real storytelling journey. We're almost educating people again on what a natural product like beer is about," van Waesberghe said. "It's all about yeast."

Heineken also uses the strain in H71, named for the longitude where the yeast was discovered. The recipe is similar to H41, but it uses more hops. It is available in France.

This could be only the beginning.

Different strains of yeast have different DNA but still fall within the same species. (This is like humans. We all have different DNA but are still considered homo sapiens. Yeast works the same way.)

Since the saccharomyces eubayanus species was discovered in Patagonia, there are now hundreds of diverse strains from Patagonia and a handful of rare strains from North America, Asia and New Zealand, according to Chris Todd Hittinger, a professor at the University of Wisconsin-Madison who ran the gene sequencing for Libkind.

"That's one of the exciting things that we've learned: The current brewing strains used industrially have a narrow swath of the genetic swatch of what's found in nature, so there's a lot more genetic variation out there in the wild," Hittinger said.

For van Waesberghe, the variety means more opportunities to create new beers. H41 is the first of Heineken's "Wild Lagers" series, and the company said more are in the works.

"For me as a brewer, this is paradise," he said. "We can just start making all new beers and styles, and I will for as long as they let me."