Good Beer Hunting

Mother of Invention

Unlikely Behavior — The Shapeshifting Story of Brett Trois

“That is what learning is. You suddenly understand something you’ve understood all your life, but in a new way.”

―Doris Lessing

Set your time machine for five years back and you’ll find yourself in a vastly different beer world. There were only about 3,000 breweries in the U.S. at the beginning of 2014, versus more than 7,000 today. Black IPAs were still hot. And the cutting edge of craft included lots of Brettanomyces, a so-called “wild” yeast that had long been considered a spoilage agent in most beer and wine, beyond its role as a traditional component of Lambic and other rustic Belgian styles. But by early 2014, Brett was being reappraised as a quality fermenter—something brewers would want to work with, rather than avoid.

In part, this was due to a single strain of Brettanomyces. Instead of the distinctive flavors (and off-flavors) that typically characterize Brettanomyces, a special version of the yeast was said to produce remarkably clean fermentations, with just a bit of Brett’s funk and fruit.


In a departure from Brettanomyces’ notoriously slow fermentation times, the yeast popularly known as Brett Trois was also said to work nearly as fast as the traditional brewer’s yeast, Saccharomyces cerevisiae. An apparent reference to its source at the 3 Fonteinen brewery (or “Three Fountains” in Dutch), the popular White Labs strain WLP644 Brettanomyces bruxellensis Trois (meaning “three” in French) was beginning to challenge everything brewers thought they knew about Brett beers.

At Omega Yeast in Chicago, however, the yeast scientist Lance Shaner was starting to have some doubts. “This strain was becoming the strain that people were using for 100% Brett beers,” Shaner says. “It just started to accumulate all this circumstantial evidence.”

That evidence? Basically everything that brewers loved about Brett Trois, from its speedy start-up time to its delicious pineapple and mango notes.

“With Brett, there’s always really, really long lag times, so if you’re growing a sample you always have a couple days before you start to see growth,” he continues. “Whereas with a Sacch strain, they start very quickly. And then there’s the acetic acid production. A real Brett strain will produce loads of acetic acid when you grow them on the plate. It will just reek of vinegar.”

Brett Trois had none of those characteristics.

“It grows fast. It handles like any other Saccharomyces strain,” Shaner says. “It doesn’t produce acetic acid. This strain isn’t even phenolic. Brett strains are all phenolic.”

It grows fast. It handles like any other Saccharomyces strain. It doesn’t produce acetic acid. This strain isn’t even phenolic. Brett strains are all phenolic.
— Lance Shaner, Omega Yeast

At the time, Shaner’s Omega Yeast offered several types of Brettanomyces, including its own versions of Brett Trois. But eventually, Shaner’s doubts about Brett Trois caused him to ask a friend from graduate school to take a look at it.

“He had it sequenced, and he said that it came back Sacch,” Shaner says.

The idea that the brewing world’s favorite type of Brettanomyces was not actually Brettanomyces would have come as quite a shock to many brewers in 2014—after all, it says “Brettanomyces” right on the package. However, the genetic sequencing used by Shaner’s friend was relatively rudimentary, meaning that the initial result was not 100% certain. Shaner decided to send the yeast to a professional research institute.

“I remember thinking, ‘It behaves so unlike a Brett, it cannot be a Brett,’ so I just went ahead and had a sample sent to Charles River [Laboratories]. Charles River does this kind of thing—they identify microbes at the species level. And they said it was Saccharomyces.”

By late fall, a few others had started to poke around under the hood of Brett Trois. Much of the conversation was taking place on Milk the Funk, a Facebook group that has long focused on brewing with Brettanomyces and other unusual microbes. In Milk the Funk’s archives, you’ll find numerous threads discussing the yeast and its behavior by late 2014, including occasional peanut-gallery speculation that Brett Trois might actually be Saccharomyces.

It was on Omega Yeast’s own Facebook page that Shaner finally made an announcement on December 7, 2014, noting that a couple of yeast strains from Omega Yeast were inaccurately classified as Brettanomyces. The conversation then continued on Milk the Funk’s pages, where Shaner clarified: “As I reported originally, Brettanomyces bruxellensis Trois is Saccharomyces cerevisiae.”

He further explained that his goal was primarily to accurately label a product he was selling. (Naturally, the comments on his post included plenty of bad puns along the lines of “BrettaNOmyces,” and Shaner himself contributed a stroke-of-genius asterisk clarifying that Omega Yeast’s Brettanomyces Blend #1 “*may not contain Brettanomyces.”) Neither of the two posts mentioned White Labs by name, but the comments revealed that people were reading between the lines: it wasn’t just Omega Yeast that had been selling a type of Saccharomyces as Brettanomyces. White Labs was, too.

I remember an usual amount of excitement in homebrewing circles about speciation of yeast and identification of yeasts. That was one of the cool things. People were pretty interested in yeast classification and microbiology all of a sudden.
— Troels Prahl, White Labs

Beyond issues of accurate product labelling, Shaner says, misidentifying a type of Saccharomyces as Brettanomyces was affecting both brewers and drinkers.

“It was tainting the knowledge pool for brewers,” he says. “It was going to affect the way consumers think about beers. It makes a difference in how you’re talking about the beers you make with it and how you talk to an informed public. It taints their expectations of what a Brett beer is. And if a brew is made with Brett, there are definitely some higher input costs, including tank residency time. If you’re using that as justification for charging more, I think that’s dishonest, too.”


Within a couple of days, the news about Brett Trois had traveled far from the original Facebook forums, and even wound up on a Dutch-language discussion board. On December 10, White Labs posted a note saying that the company had received “some questions as to whether White Labs WLP644 Brettanomyces bruxellensis Trois is not a strain of Brettanomyces.” The company noted that it was doing its own research on the strain, including sending the yeast to outside laboratories, and that it would share more information when it had “a definitive genetic answer.”

A few months later, White Labs announced that it was definitively reclassifying WLP644 as a type of Saccharomyces.

All of this might sound like a not-great experience for White Labs, since the company was the main source of Brett Trois at the time. But when you talk to White Labs employees today, you’ll get a different impression.

Troels Prahl is the vice president of innovation and European operations for White Labs in Copenhagen. When asked about his memories of the Brett Trois controversy, Prahl was resolutely positive.

“I remember an unusual amount of excitement in homebrewing circles about speciation of yeast and identification of yeasts,” he says. “That was one of the cool things. People were pretty interested in yeast classification and microbiology all of a sudden.”

Another upside, Prahl adds: brewers who were afraid of working with Brettanomyces due to possible contamination issues now had a version of Saccharomyces that offered some of the appeal of Brettanomyces without the risk.

“The main memory I have from that time is that a lot of people were suddenly super excited that they could play with it without having the concern of having to deal with Brettanomyces in the brewery,” Prahl says. “It [Brettanomyces] tends to form more biofilm, it tends to be a little more hardy in terms of how it can hide in the brewery, and if you have a Brett contamination of a non-Brett beer, it will develop that Brett character and will tend to over-attenuate. There are a lot of reasons why you wouldn’t want it in your brewery. Once it was discovered that it was a Saccharomyces cerevisiae, then all of a sudden a lot of those fears turned out to be insignificant.”

That sense of no longer having to worry about Brettanomyces contamination seems to have been widely shared. Shaner made a similar comment in his original post announcing that Brett Trois was really Saccharomyces, an idea that many passionate Brett Trois fans didn’t want to accept at the time.

“Look on the bright side,” he wrote. “People afraid of introducing Brett into their breweries should be able to use this strain with no fear and enjoy the results it provides.”

“If this hadn’t come out, what would people be thinking about Brett beers? Because now, I think, the thinking about Brett beers is aligned with how Brett beers really are.
— Lance Shaner, Omega Yeast

A related benefit, Prahl says, was the increased focus on sanitation and proper handling procedures in breweries where both Saccharomyces and Brettanomyces were being used.

“One of the things we saw in that time was that craft breweries were developing their own guidelines for how to handle non-Saccharomyces beers in the same environment as Saccharomyces beers, and with really good results.”

Improved sanitation was a clear win for breweries. Increasing consumer awareness of different types of yeast and how they work counted as another clearly positive result.

“You’d see on Milk the Funk, ‘Oh, Brett beers are really quite clean, you can make them really fast,’” Shaner says. “But now we know that’s not true. If this hadn’t come out, what would people be thinking about Brett beers? Because now, I think, the thinking about Brett beers is aligned with how Brett beers really are.”

That continuing realignment is part of a much wider trend in scientific understanding today. Prahl notes that the genetic advancements of the past half-decade have turned scientific classifications upside-down—and not just in the world of beer. While earlier biological classifications were made based on observable traits or characteristics, recent genetic testing has caused scientists around the world to suggest reclassifying philodendrons, tigers, grasshoppers, and even rails.


“Five years ago, it was already reasonably ‘easy,’ in quotation marks, and it was relatively cheap,” Prahl says, when asked about genetic testing for yeast strains. “But if you go back 10 years, it was a whole different story. And what we saw after the advancements in both PCR [polymerase chain reaction, a technique that permits the analysis of a short sequence of DNA or RNA] and especially sequencing, was that a lot of those old classifications were not correct from a genetic perspective.”

Even before Brett Trois was reclassified, Prahl says, the company had embarked on a multi-year study of all of its microbes, which provided White Labs with the data for a groundbreaking 2016 paper about the origins of ale yeast.

“It was definitely a cool discovery as part of our sequencing efforts,” Prahl says. “We have made several discoveries in all the work we did involving full sequencing of all our strains.”

The results of that research—and the ensuing new discoveries—are still unfolding. Pretty soon, there might be a new shakeup that echoes what happened with Brett Trois in 2014.

“We’re coming out with a pretty interesting paper here about hybrids,” Prahl says. “One of the things that was remarkable when we got all that data about the sequencing was how many strains around the world are actually hybrids—which means that there are going to be several new reclassifications.”

Words by Evan Rail
Illustration by Ben Chlapek