Bread, wine, beer … all civilizations have fermented foods using “Saccharomyces cerevisiae”, brewer’s yeast or baker’s yeast. But who started? Most likely the Chinese. This is what a large study of the evolution of its genome recently revealed.
By sequencing more than a thousand complete genomes of yeast strains collected around the world, Joseph Schacherer, at the University of Strasbourg, Gianni Liti, at the University of Nice, and Patrick Wincker, at the Genoscope, in Évry, have shown that while this unicellular fungus has been independently domesticated many times, it has only one origin: an ancestral strain that thrived in China !
When scientists in France set out to sequence 1,000 yeast genomes, they looked at strains from all the places you might expect: beer, bread, wine.
But also: sewage, termite mounds, tree bark, the infected nail of a 4-year-old Australian girl, oil-contaminated asphalt, fermenting acorn meal in North Korea, horse dung, fruit flies, human blood, seawater, a rotting banana.
For five years, two geneticists—Gianni Liti, from the University of Côte d’Azur, and Joseph Schacherer, from the University of Strasbourg—asked for samples of “Saccharomyces cerevisiae” from nearly everyone they met, whether doctors in French Guiana collecting human feces or Mexican tequila makers !
The results of their analysis, published in Nature, suggest that yeast came from, of all places, China…
The out-of-China hypothesis for yeast is not so different from the out-of-Africa hypothesis for humans. Among Homo sapiens, Africa has the most genetic diversity of anywhere on Earth. All humans elsewhere descend from populations that came out of Africa; all yeast elsewhere descend from strains that came out of East Asia. Once wild yeast strains made it out of Asia, humans likely domesticated them several times to make the yeasty foods that we know: beer, bread, wine.
By the way, Belgium famously produces hundreds of different beers, but that is nothing compared to the varieties of yeast used to make it – around 30,000 are kept on ice at just one laboratory by scientists seeking the perfect ingredient for the perfect brew !
Kevin Verstrepen, a geneticist at KU Leuven, Belgium, who has sequenced many strains of domesticated yeast used in beer, is also enthusiastic: “Everybody in the yeast community is quite excited,” he says.
And if you’re wondering if wild yeast can indeed be used to brew beer, the answer is yes. Yeast is yeast. It turns sugars into alcohol. But don’t expect great results. “We’ve done quite a few of them,” says Verstrepen. “Let’s say the beers are funky ” !
