Yeast Ranching: Wrangling Wild Yeast and Other Microorganisms, Off the Grid

Feature by | Aug 2013 | Issue #79

Oxbow's Tim Adams filling barrels.

A yeast grows in Brooklyn. Several strains of wild yeast, actually. At home in his DIY laboratory in Sheepshead Bay in south Brooklyn, Dmitri Serjanov isolates yeasts from bottles of Belgian beers like Cantillon and Saison Dupont. After drinking the beer down to the dregs, he pours the yeast out, grows a colony on petri dishes and inoculates a small amount of low-specific-gravity wort. He then offers his stockpiled yeast to brewers on the internet—Serjanov’s online handle is BKYeast—in exchange for other beers and yeasts, or for $10 to cover shipping.

Tucked into a corner of his small apartment, Serjanov’s lab consists of a bookcase lined with beakers, test tubes and erlenmeyer flasks, and a desk that holds a microscope connected to his computer. He installed a mini-hood and encased the area with fiberglass to keep it sterile. The squat refrigerator nearby is actually an incubator kept at 86° Fahrenheit, optimal growing conditions for yeast. He also has a narrow workspace for pipetting, stirring and mixing, and spreading yeast colonies on petri dishes. When his work is done and it’s lights out, an eerie ultraviolet light stays on, keeping his shelf sterile.

Though his day job is as a molecular biologist at a local medical school, Serjanov is a self-proclaimed yeast rancher. And the yeast he’s wrangling in his laboratory—which is undeniably better outfitted than those at most microbreweries—reflects a larger trend. In their quest to push the boundaries of brewing and redefine craft beer styles, American brewers are deep into experimenting with brewing’s most fickle ingredient: wild yeast.

Prized for the nuances the yeast imparts on beer—which include earthiness, spiciness and that inscrutable “barnyard” character—Brettanomyces is the most popular of the wild yeast once only seen in Belgian Lambic beers that were fermented by throwing open the brewery doors rather than throwing in a yeast slurry. And as demand for Brett and other wild strains skyrockets, geeks like Serjanov are stepping up to meet it.

Go Brett or Go Home
Leading the Brett charge are artisanal American breweries like Crooked Stave in Colorado, Maine’s Allagash and Oxbow breweries, Anchorage Brewing in Alaska, and California’s Russian River and The Bruery. They’ve developed innovative recipes, added specialty ingredients like hibiscus and rye, and inoculated with strains of Brettanomyces. Using Lactobacillus and Pediococcus bacteria that give off lactic acid, a souring agent, they’ve also riffed on European sour styles, like tart, light-bodied Berliner Weisses and sour, malty Flanders Browns.

“Once I started experimenting with Brettanomyces, I fell in love with it,” says Gabe Fletcher, owner and head brewer of Anchorage Brewing Company in Alaska. He uses Brett in almost every beer he makes, and most of those sit around aging in barrels for six months to a year. “It’s really an amazing yeast once you embrace what it can do and give it its time.”

Fletcher praises Brett’s ability to scavenge for oxygen in his hoppy beers, a characteristic that keeps beers like Galaxy and Bitter Monk fresh after a year or more.

While Fletcher sources from yeast banks in the “lower 48,” and from his growing culture of bacteria and wild yeast donated by Russian River, some pro brewers are reaching out to hobbyists like Serjanov.

“Sometimes they just hear about it and want to give it a try, sometimes they have tasted homebrew made with it and liked it well enough to want to do it themselves,” Serjanov says. “As far as I know, there are commercial batches already bubbling away in some places with yeast I isolated from Cantillon bottles.”

As many professional brewers know, homebrewers offer a wealth of hair-brained ideas that wouldn’t be worth researching or developing at a commercial brewery. Which is why if you’re looking for people isolating and brewing with wild yeasts and bacteria, you needn’t look any further than the homebrewing community.

Yeast Traps
When Jeff Mello goes on vacation, his packing list always includes an agar plate, sterile cotton swabs and a test tube; the mason jars of unfermented wort that he uses at home don’t travel so well. He leaves the “yeast traps” outside to collect anything floating around the garden. Like a wine’s terroir, Mello wants to find strains that are specific to a certain place. He recently dubbed a species of yeast he found and isolated from his own backyard “Saccharomyces arlingtonesis,” after his hometown, Arlington, Va.

Mello calls his open-source yeast project “Bootleg Biology,” and though he has no formal science training, he’s learned to make his own petri dishes and identify ale yeast colonies by sight, and he’s tweaking a growing medium that will only host Brettanomyces (adding lactose to the agar has produced mixed results, but he’s got more promising agar media in the works).

“Crooked Stave and Russian River are putting out beautiful beers that are in high demand,” says Mello, who recently left the nonprofit world to work on Bootleg Biology and in a craft beer shop. “Why not harvest your own funky strain?”

Homebrewing first piqued Mello’s interest in the hobby; then he read Yeast, Jamil Zainasheff and Chris White’s tome on the subject. He says the section on building your own yeast lab is probably aimed at scientists with large-scale aspirations—and while commercial yeast labs are great, Mello says, “I also wanted to do something a little more holistic. So in addition to isolating local yeast, the goal of Bootleg Biology is also to create the most diverse library of brewing microbes and cultures possible. That means all cultures are sourced and isolated exclusively from ‘bootleg’ sources like the air, kombucha, yogurt, honey, fruit and whatever else we can get our hands on. Some are isolated, but many remain as a blend or mix of cultures that can be brewed with directly.”

Eventually, Mello will sell and trade his cultures online, but for now, he’s handing out samples to “adventurous souls” at events and homebrew club meetings. In return, he asks that brewers send him their fermentation metrics. “The goal for the near future is to build a solid database that aggregates that data, with analytics for each strain displayed on”

That kind of precision and documentation is important, says Ben Woodward. Woodward is isolating his own cultures in Saxapahaw, a small town smack dab in the center of North Carolina. He and his wife, Dawnya, are months away from opening up Haw River Farmhouse Ales, a 10-barrel brewery that will feature local yeast.

Last February, Woodward set out a few yeast traps covered in cheesecloth around town. After harvesting three samples that smelled promising and wondering how he was going to brew with them, he was approached while he was pouring at a beer festival.

“Deborah Springer, a postdoctoral associate at Duke University Department of Molecular Genetics & Microbiology, had read our blog post and offered to help clean up our samples, isolate the yeast cells and run DNA sequencing on them to help organize our efforts,” says Woodward. The bug turned out to be a strain of Pichia fermentans yeast, which shows up about a year into Belgian Lambic fermentations. Woodward hopes to use it commercially as the primary yeast for his year-round Belgian Blonde.

“Yeast is one of the last unexplored ways of brewers giving their own spin on recipes,” he says, citing Mystic Brewery (in Massachusetts), Jester King (Texas), Jolly Pumpkin (Michigan) and Odell (Colorado) as examples.

Woodward is about to start working with the vineyard across the Haw River to isolate a strain of Brett from its grapes to use in the secondary fermentation of an upcoming brew. “That way, we could ferment with a truly Saxapahaw Brett,” Woodward says.

History Repeating
Charlotesville, Va., brewer Hunter Smith thinks of Brett in its historical context. With the rise in popularity of Brett, the owner of Champion Brewing thinks it’s funny that brewers and winemakers used to be so preoccupied with eliminating it from their barrels. In fact, he’s watched as his father and the staff have “worked tirelessly” to stave off Brett infections at his parents’ vineyard in the nearby Blue Ridge Mountains. Now, he purposefully inoculates their old barrels.

“I’ve got a beer going in the barrel now,” points out Smith. “It’s a 9-percent American Pale Sour being aged in Afton Mountain Chardonnay barrels with Brettanomyces, Lactobacillus and Pediococcus.” One winemaker’s Brett barrel is another brewer’s treasure.

The breweries of old most likely had barrels rife with souring bacteria or Brettanomyces-esque bugs, whether by design or not. In fact, people who have plumbed historical accounts of 19th-century Porters—which were aged in wooden barrels—have found mentions of “sour,” “tart” and “astringent,” which leads them to believe that the barrels Porters were once-upon-a-time aged in were also home to bacteria and wild yeast.

While some attempts at homegrown yeast might end up in the compost bin, Fletcher of Anchorage Brewing says that the successes are worth the trouble.

“I have done wild fermentation before with great results. I’ve also had not so good results,” he says. “But that’s the chance you take when dealing with wild yeasts. That’s why they are called wild—you don’t always know what the result will be, but you won’t know unless you try.”

Photo by Michael Donk

Photo by Michael Donk

Safety First (Yeast Harvesting Tips from White Labs)

“There are a lot of characteristics that are very specific to Brett,” says Neva Parker, head of laboratory operations at White Labs, a leading retailer of brewing yeasts in San Diego, Calif. Parker has spent a lot of time raising Brett, and identifying whether samples sent in by brewers are yeast or bacteria.

“Brett are very high acid producers for a wild yeast, so we grow them on a [medium] that has an alkaline buffer,” explains Parker.

Her plates have calcium carbonate embedded in them; she offers up Tums as a ubiquitous substitute. “If they are Brett or a Brett-like species, they will produce a lot of acid clearing.” In other words, when the Brett colonies grown on top of a cloudy, gelatin-like agar, a smooth, clear halo will form around the colonies, because—if you remember your Chemistry 101—an acid (the Brett metabolism) and a base (the calcium carbonate) neutralize each other.

Parker stresses that harvesting wild organisms can be risky for novices. If fermentation doesn’t happen, “then the beverage isn’t safe to drink, because you could be capturing something that is potentially pathogenic,” she says. “Ethanol and low pH are key to keeping out the bad bugs.”

She suggests that DIY yeast ranchers should have a strong background in microbiology and yeast culturing; start by “getting familiar with culturing and maintaining brewers yeast, then apply these techniques and foundation to culturing other organisms,” she says.

If the yeast sample does ferment, then “you’re not going to die,” she laughs. “With fermentation, the pH drops, and you get alcohol made. The organisms that are going to survive that are not going to hurt you.” But still—be careful out there.