Many ancient civilizations considered booze to be a heavenly gift bestowed by the deities they worshiped. Centuries later, scientists would discover that these intoxicants were instead the byproduct of a tiny being much closer to home: yeast. This single-celled microorganism thrives off of sugar and converts it into alcohol, turning malted grain into beer, and crushed grapes into wine.
Winemakers have come to realize that there are many different strains of yeast (and even bacteria) at play that enhance the aromas and flavors of wine derived from a variety of grape vines. Whether you’re tasting the tarty fruitiness of a red wine, the buttery, creamy feel of a Chardonnay, or the bitter acidity of a wine that’s gone bad all depends on the microbes chomping away in the barrel.
“[Winemaking] is part science and part art,” Linda Bisson, a molecular biologist who has researched wine at the University of California, Davis, told The Daily Beast. “People who get to know their food—because they’re winemakers, they’re tasting and tweaking things—they become real artisans in how to get the flavor profile they want.”
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But despite that, Bisson said, both winemakers and scientists still don’t fully understand how the microbial communities involved in wine fermentation interact with each other, what chemical signals they convey to one another that influence an aroma or flavor, or which yeast are doing the actual fermenting.
Some scientists are hoping to cut through the unknown with the help of genetic engineering—proposing that one day, winemakers could rely on genetically modified yeast to fine-tune their brew.
Typically, there are two types of yeast used to make wine. Saccharomyces cerevisiae, also known as baker’s yeast, is commonly used in the industry and ferments grape juice quickly, producing just the right levels of alcohol that give a wine its longevity and buzz. Wild yeasts, on the other hand, are a bit slower to the punch. These types like Metschnikowia pulcherrima or Pichia kluyveri are naturally found on grapes and, if used without S. cerevisiae, make what French enologist Pascal Ribéreau-Gayon refers to as “lower-quality wines with lower alcohol strength.” But these wild yeasts are essential for making wine with complex flavors and also help retain a vineyard’s characteristics.
When the two types of yeast are placed into a fermentation vat, winemakers generally pour in wild yeast first and add commercial yeast (called an inoculation) a few days later, Vivien Measday, a microbiologist who studies S. cerevisiae at the University of British Columbia, told The Daily Beast. This is because S. cerevisiae produces a lot of alcohol upfront, and can tolerate alcohol concentrations of up to 15 percent. Wild yeast, on the other hand, die when alcohol content rises above 7 percent.
This sort of competition underlines the delicate balance and variability within a community of yeast. Both wild and commercial yeast can stop working for a variety of reasons, such as the presence of too little or too much of a yeast strain, suboptimal temperatures, or lack of nutrients. Bad yeast can sometimes kill off the good yeast. One wild yeast called Brettanomyces bruxellenis is infamous for wine spoilage and tends to contaminate up to 25 percent of red wines. While winemakers do use sulfur dioxide to prevent B. bruxellenis from growing, the wild yeast appears to be developing a resistance to the chemical compound akin to antibiotic resistance in bacteria. Wine quality, in other words, is at the mercy of a host of fickle factors.
That’s where genetic engineering can make an impact, Roy Walker, a molecular biologist at Macquarie University in Sydney, told The Daily Beast. Wine yeast could be genetically modified to resist spoilage yeast, or perhaps release antimicrobial chemicals that target B. bruxellenis. Some strains could be designed to work together instead of competing—each specializing in specific tasks that a winemaker could precisely control to engineer the perfect wine.
“The hope is that to start assembling these complex microbial communities, we will understand their interaction a lot better to help uncover some of the dark matter of microbial interaction,” said Walker.
So what would one of these microscopic communities look like? Walker and his Macquarie University colleague, Isak Pretorius, propose that within a fermentation tank, a winemaker could have four types of “worker” strains consisting of both commercial and wild yeast: heavy lifters responsible for reliable yet fast fermentations, attributors responsible for producing a wine’s sensory and aromatic properties, biosensors that detect undesirable compounds like smoke taint (what happens when vineyards are exposed to smoke such as from wildfires), and controllers who are overseers managing and regulating everyone else.
These workers could also be made to be co-dependent on each other so that if one stops working for whatever reason, its co-workers also fail to clock in. A fail-safe mechanism like that would assuage any concerns the public might have about what would happen if a genetically modified yeast somehow leaked into the environment (also make it impossible to crossbreed with any wild strains).
Additionally, winemakers could genetically modify the worker strains to respond to external stimuli like electricity or light (though there are concerns that exposure to ultraviolet light will lead to a loss of aroma and cause the wine to smell like cooked cabbages or onions).
But while the potential for gene modification to improve winemaking is pretty vast, it would take a compelling reason, and a lot of convincing, to get the industry to embrace these new technologies.
“Genetic engineering solutions to wine problems never caught on,” Bisson said. “I think one of the main issues was, ‘What problem are you trying to solve, why is this a solution, [and] why would I want an organism that did that?’”
Moreover, genetic engineering doesn’t have the best track record of success so far. Over the last few decades, modified yeast strains have done well in the lab. But in trials scaled for actual wineries, Bisson said these strains died on the vine faster than their natural counterparts.
Even if the genetically modified yeast stays healthy, getting them to fulfill desired tasks is a Herculean feat. Years ago, Bisson and her team at UC Davis tried to modify yeast to not produce hydrogen sulfide, the chemical compound behind the rotten egg smell, during fermentation. They were unsuccessful.
“We [tried] knocking out this gene, do this or do that, and there were so many failures that I’m like, you know what? I’m just going to have to go to Mother Nature and find a strain that does this,” she said.
And for the most part, that’s what the wine industry has been doing: scouring nature’s catalog for yeast that have developed spontaneous mutations for desirable traits (like not producing hydrogen sulfide), and selectively breeding them with other yeast much like you would cattle, said Measday.
There is one looming threat on the winemaking horizon that genetic engineering could help the wine industry with: climate change. With unseasonably warm winters, hotter summers, and unpredictable weather patterns like violent storms, droughts, or forest fires, grape farmers and winemakers are taking hits left and right. In Europe, the International Organization of Vine and Wine released a report in 2021 describing how much wine production had tanked, particularly in Italy, Spain, and France, due to unfavorable climatic conditions. (Still, in other countries, like Germany and Romania, wine production has never been better.)
Though these effects have more to do with grape health than anything else, there is some thought within the scientific community that yeast can protect grapes against a rapidly changing environment, allowing wineries in vulnerable locales to limit their losses. Genetically engineering yeast to be resistant to extreme heat or climate fluctuations could, by extension, help grapes survive as well.
“Some of these yeast species have the ability to kill off unwanted fungal species like powdery mildew,” said Measday. “There’s lots of potential diseases that could be helped by yeast, so you may run into trouble with disease persistence because you got rid of all the good microbes. It’s a definite possibility that the microbiome of a vineyard could be messed up.”
But winemaking is an industry that’s proud and stodgy about tradition. For Matthieu Finot, a winemaker at King Family Vineyards in Virginia, the unpredictable nature of winemaking is not a bad thing—just another part of the craft.
“For us winemakers, we are much more farmers blending farming, science, and art,” he told The Daily Beast. “We are a bit artistic and, in that sense, sometimes like the unpredictability of what we do. Every year is going to be different, there’s always going to be a challenge that will arise but we’re willing to embrace it.
