What does Big Bend taste like?

That’s one of the questions Rob Green and his wife and business partner, Mara Young, are answering at San Antonio’s Community Cultures Yeast Lab. There, they test and propagate yeast strains, collected from the state’s native plants, flowers, and insects, that are used by craft brewers to make beers that taste like Texas.

Green, an avid home brewer, was finishing his undergraduate degree in biology at the University of the Incarnate Word in San Antonio in 2016. While kicking around thesis ideas for his graduate school application, he became interested in the potential of using indigenous yeasts for brewing.

He and Young, whose background is in botany and ecology, were already collecting yeast samples from their favorite Texas locales whenever they went hiking, kayaking, or camping.

“A friend of ours with craft brewer contacts said they’d expressed interest in using some of the native yeasts we’d collected,” Young says. “That’s when it just clicked: let’s see if we can’t map the terroir of Texas through indigenous yeast collected from the state’s most beautiful places.”

Green ultimately passed on grad school to open Community Cultures in 2018. It’s the only yeast lab in the southwestern United States, and most of its business lies in selling hundreds of universally recognized brewer’s yeast strains—as well as mixed cultures, wine yeast, whiskey yeast, and custom propagation. Offerings from the lab’s seasonal native catalog—what the couple calls its “Texas strains”—make up just 2 percent of its business. But the native yeasts are a labor of love for the couple. To date, they’ve been used to ferment beers at Texas breweries including Jester King Brewery, Vista Brewing, and Beerburg Brewing.

Community Cultures Yeast Lab Beerburg Brewing
Trevor Nearburg of Beerburg Brewing uses yeast from local grapes for an upcoming brew.Lisa Hause/Beerburg Brewing

This is an opportune moment for a crash course on brewer’s yeast. There are two dominant strains of brewer’s yeast: Saccharomyces cerevisiae and Saccharomyces pastorianus. Their flavor and aroma profiles (what Community Cultures calls “expressions”) vary depending upon the place of origin. Most of these strains are sourced on-site at famous breweries and then propagated in yeast labs worldwide.

Craft beers made with “wild” or “ambient” yeast are typically fermented with exposure to the yeasts in the surrounding brewery environment. Some brewers, however, use the term “wild” as a pejorative to describe beer with bacterial contamination. The nomenclature is confusing, even for brewers, because there’s no regulation on the terminology.

“Anything incorporating more than monocultures of traditional strains of brewer’s yeast is ‘wild,’” Jeffrey Stuffings, founder of Jester King, explains. “The ‘native’ part is just relative. For us, wild yeast from Texas is native. For a brewer on the other side of Earth, the same strain wouldn’t be native.”

To obtain their native yeasts, Green and Young take swabs from endemic botanicals like Torrey yucca, ocotillo, and columbine, using collection kits that don’t necessitate picking plants.

In the lab, each sample is isolated from any bacteria and grown as a single pure culture to determine if it’s a viable strain of brewer’s yeast. If it is, it’s cultivated and propagated like any commercial yeast strain and tested in nano-batches of beer.

From there, the lab documents the yeast’s expression. “The flower or whatever plant the yeast comes from is just part of its story,” Young says. “The dominant expression of a native yeast is actually determined by its subspecies.” Yeast that makes the cut is usually named for its host or locale. The Window is a Saccharomyces cerevisciae strain from a prickly pear cactus tuna and was named after the Big Bend National Park hiking trail where it was collected. Community Culture describes it as “lightly floral,” with “hints of bubblegum, stone fruit, warm spices and cracked pepper,” and suggests that it be used to make “Belgians, Weizens, Trappist ale, Dubbels, German ale, and Saisons.”

A common belief is that native yeasts can produce only sour beers. But that’s incorrect, according to Young. “They can be used for many styles, and have applications for other fermented products as well.” Corpus Christi’s Lazy Beach Brewing, for example, makes a hard kombucha from a native yeast, and the lab has had bakers, winemakers, and makers of fermented foods express interest.

The biggest obstacle to selling native yeasts is persuading brewers to try something so misunderstood. “For many, it’s deeply ingrained that natives are dirty, funky, and risky,” Young says. “There’s a lot of misinformation about what it is we’re doing; we’ve had brewers say they don’t want to infect their beer by using native yeast.”

Despite the detractors, there is a market for these yeasts, driven by young craft brewers eager to try something new. “It’s exciting to them,” Young says. “It’s called craft beer because it’s a craft. With native yeast, it’s like cooking with local ingredients—you’re not going to get the exact same dish a month later. For some brewers, that’s okay.”

Jester King was the first Texas brewery to make fermentation with ambient yeast its primary focus. The brewery also collaborated with Community Cultures on a 2020 Desert Series. Two dry-hopped oat saisons were fermented with salvia and prickly pear yeast from two microregions in West Texas.

“We were interested in seeing what yeasts from the West Texas desert would produce in terms of flavor and aroma in beer,” Stuffings says. “Microbial terroir is an important element in the regional character of wine, and the concept as it applies to beer is fascinating to us.”

Community Cultures sells native yeasts from the Gulf Coast, the Hill Country, Houston, San Antonio, and the Big Thicket National Preserve too, as well as Mexico’s Yucatán Peninsula, where Young’s parents reside.

Green and Young also collect yeast samples from pollinators like butterflies and bees, which are unharmed in the process. One day, when the couple was at Driftwood’s Vista Brewing, a honeybee from the brewery’s apiary flew into the production area. Green was able to obtain a sample and found the bee was carrying Saccharomyces cerevisiae. The result was Vista’s Hive Mind Honey Ale, a light, effervescent Belgian-like brew made with barley from Fort Worth’s TexMalt and honey sourced from 25 Central Texas beekeepers. The release was so successful, Vista is doing a second Hive Mind project this summer.

For Trevor Nearburg, a brewer, herbalist, and founder of the Hill Country’s Beerburg Brewing, native yeasts were the missing link in his beers, which are made primarily from native and foraged ingredients. He and head brewer Gino Guerrero have worked with various native yeasts, including Community Cultures’ Buttercup, collected from blooms along the Rio Grande, for a mugwort barleywine and a pecan-mesquite bean brown ale; and Prickly Pear for a horehound golden ale. The brewers are also running trials on yeast they collected from mustang grapes, juniper berries, and persimmon trees on their property.

Green and Young realize that native yeasts will remain a small part of craft brewing. It’s their passion project—one that allows them to explore and represent the wild places of Texas.

“Why are so many people willing to spend twenty-five dollars on local honey or fruit at the farmers market?” Young asks. “It’s because they want to support their food shed, while still getting a good product. That’s what’s happening right now in Texas [beer].”