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In the fray of the holiday, we often forget the significance of the food on the Thanksgiving table. Almost all of it is made from ingredients—plants and animals—that are native to the Americas. Squash, beans, and corn. Cranberries, blueberries, and pumpkin. The tender turkey and the humble potatoes. It is the contents of the banquet that give it context, underscoring its origins as an event of intercontinental exchange between the Native cultures of the Americas and the interloping Europeans.
Centuries of trans-Atlantic swaps brought new species to foreign places (like the tomato in Italian cooking and horses on the North American plains). But invisible organisms were also exchanged—microbes unseen by the human eye stowed away on fruit skins, in animal hides, and even in the wood of the ships themselves. Galleons carrying humans carrying diseases arrived in the Americas. Viruses like smallpox and bacteria like typhus came from Europe and decimated Indigenous populations who had no immunity, never having been exposed to the microbial scourges before.
When transoceanic exchange between the Americas and Europe first began in earnest, humans only had the earliest ruminations of germ theory. Where Europeans acknowledged the novelty of things like corn, alpacas, and potatoes, they would not have immediately understood the extent of the transfer of microbial organisms. While these invisible exchanges had dire health consequences around the world, microbes also played a prominent role in the culinary realm. In fact, some 350 years before we even began to understand microbes, an invisible Columbian Exchange occurred that changed our fermented beverages in unexpected ways.
Yeast, any brewer can tell you, makes all the difference in the taste of a beer or cider or wine or whiskey. Not only do the single-celled, alcohol-producing fungi make our drinks boozy, they also help develop distinct flavors. Nowadays, specific, almost bespoke strains of yeast are harnessed by scientists to be used for mass-produced drinks, guaranteeing consistent flavor between batches and optimizing yields for profit. Like any other product in the agro-industrial sector, yeasts have been selectively bred, patent-protected, and monocultured. But these infinitesimal beverage-makers were traditionally controlled by brewers using ancient production techniques. They are also far more diverse than we know. If tomatoes transformed Italian cuisine and pack animals revolutionized transportation in the Americas, how did microbial exchange change the production and flavor of our favorite fermented drinks?
Though little appreciated, the cultures and colonies of microbes that European brewers relied on for beer- and wine-making have invaded Indigenous fermentation here in the Americas. But few modern Americans even know about the vibrant landscape of Indigenous fermented drinks that existed pre-colonization and persists here in the Western Hemisphere. Perhaps this is because very little alcoholic fermentation was practiced north of Arizona. The legacy of drinks like colonche (deep-red prickly pear cactus wine), tepache (piquant fermented pineapple juice), and pulque (gooey and opalescent fermented agave sap), as well as a complex of different corn beers in the Chihuahuan and Sonoran deserts, are rarely discussed and poorly appreciated.
“We had concepts even without understanding bacteria and yeast and microbiology, like the construction of our fermentation vessels—understanding that to make good beer you don’t wash your fermentation vessels,” reflects Rox Tiburolobo, an Indigenous brewer and distiller who is of Chiricahua Apache and Rarámuri descent and currently works with strains of yeast as a technical sales manager for Lallemand Biofuels and Distilled Spirits. He shows me a clay olla bowl inherited from his grandmother to show the porosity of the clay, an attribute that makes it perfect as a home for microbes and thus a container for fermenting corn beer. “With tesgüino [Rarámuri corn beer], and particularly batari [another corn-kernel beer], we traditionally add grasses and lichens that have a similar antimicrobial effect as hops.” The Indigenous biotechnology of booze was as complex and encoded in culture as Europe’s fermentation tradition. But many of these drinks transformed with the arrival of Europeans.
The first European-style brewery opened in Mexico in June of 1542, when King Charles V granted the first license to brew beer in New Spain to Alfonso de Herrera. It was a short-lived project, but barrels of beer and wine in the holds of ships arriving to colonized lands throughout North and South America would have carried the invisible yeasts that made those drinks. While it is hard to measure how the introduction of such yeast and bacteria may have changed Indigenous drinks, we have reason to believe that they did.
Microbiologists are now dip-sticking the world’s traditional fermented drinks to understand the exact species that contribute to a fermentation. Science is just coming to appreciate the diversity and complexity of these microbial populations, which can involve dozens of different species of yeasts, molds, and bacteria working in conjunction to digest plant matter and produce intriguing combinations of alcohol and flavor compounds.
Dr. César Iván Ojeda Linares, a postdoctoral researcher in ethnomicrobiology at the Center for Genomic Sciences of the National Autonomous University of Mexico, tests Indigenous drinks to see what microbial species they contain. He tells me that he believes some remote holdouts have actually avoided European microbes altogether: “The microflora—the yeasts we find in the atmosphere—continue to remain. There are exemplary cases where there has not been this introduction of external species.”
His research has focused on Indigenous Mexican cactus wines. Where most of the wines he and his team tested do contain the genus Saccharomyces (of the common beer yeast), he adds, “In the isolated Coomcac community [an indigenous group in Sonora, Mexico], which continues with the tradition, what we found was that there was no Saccharomyces. For me this is surprising, because it shows that we still have something isolated. It is like a relic of that past, even though they use plastic barrels in place of the traditional barrel-cactus container.”
For a century, we have known that some Indigenous American drinks contain microbes different from standard European beer and wine. As the field of microbiology matured toward the end of the 1800s, a prominent early scholar from Germany, Paul Lindner, began to look outside of Europe for different microbes. He tested South African sorghum beers, and in the 1920s he came to Mexico to do experiments on behalf of the Mexican government to understand pulque, made from agave sap. The result of his research was the discovery of Zymomonas mobilis (originally called Pseudomonas lindneri after the scientist). The discovery marked one of the first times that microbiologists understood that a bacteria could produce alcohol at a higher rate than yeast.
While it seems that today, brewer’s yeast has settled into many of the traditional brewing houses of Indigenous America, fermentation is not only about yeast. “We’ve imported all these organisms that bring all these other organisms on them. So there’s no way that fermentation hasn’t shifted with time,” Tiburolobo says. “I’m sure if we tasted some of these beverages a thousand years ago, they would have tasted very different than now. But how much of that is also just because of the climate shifts and things like that? Fermentation doesn’t exist in this tiny bubble of just one factor.”
Wine buffs will know that local North American grapes and their many pesky diseases like phylloxera changed global wine production forever (almost all wine grapes are grown on vines with European branches grafted onto North American roots). Similarly, Indigenous American fermentation has had a lasting impact on brewing in the Eastern Hemisphere. The world of beer, for example, is bifurcated by the use of either ale yeast (Saccharomyces cerevisiae) or lager yeast (Saccharomyces pastorianus). Lager, a style of beer developed by German monks through fermenting in cold caves in the 15th century, is now produced with a yeast that is likely a hybrid of European beer yeast and a strain of cold-tolerant yeast from the chilly southern forests of Patagonia.
Lagering existed prior to the introduction of this Chilean yeast to Europe, but once the cold-tolerant yeast sailed across the Atlantic and into the cool beer caves, it would have thrived in the environment, challenging traditional yeast and hybridizing until a new strain was born.
Competitive advantage or dominance in an environment is a key factor that influences which microbes will enjoy the sugars in our drinks, converting them to alcohol through their metabolism. While the hardy parent of lager yeast lives in other parts of the world, South America is generally accepted as its place of origin. Today, well over three-quarters of all beer produced in the world is made in the lager style.
Tiburolobo also notes that it would have been Indigenous groups in the present-day United States who taught the first European settlers how to germinate or malt corn where wheat and barley were not yet planted to be fermented into beer. This transfer of knowledge would have laid the groundwork for the earliest versions of America’s beloved bourbon whiskey.
It is difficult to comprehend the universal impact of the invisible organisms that shape so many of our foods and drinks. Robust trade between continents was ongoing for three centuries prior to Louis Pasteur’s groundbreaking descriptions of fermentation. How can we know the degree of microbial exchange that occurred over those years? Modern microbiologists can use genetic data to trace a yeast’s lineage back to a wild population—but not many do. There is little interest in quantifying and cataloging the many microbes that transform traditional food.
Yet, as we gather around the table at Thanksgiving once more, we should consider the give-and-take of this exchange and maybe focus a bit more on the microscopic. Just as the world’s table was made more bountiful and diverse with the introduction of new species from different continents, the world’s goblet underwent a more subtle transformation—and an irreversible one. Once these microbes successfully compete in a new environment, there is no way to eliminate them. The same historical process that has combined wheat bread and turkey to form this little gravy-soaked biscuit in my hand has also changed how the world brews forever.
