So we domesticated the yeast that provided humans with wine and beer

Since the Neolithic period, when the collection or capture of plant and animal species ceased to be the basis of that species’ diet, our existence – and most importantly the development of civilizations – has been a consequence of human existence. domesticated.

by means of Agriculture and Livestock We select, improve and adapt to our needs: grains, fruit trees, garden plants, birds and ruminants for the production of eggs, meat, milk… and more recently, even fish.

But sometimes we forget that we also empirically domesticate unseen creatures: microorganism Necessary for the manufacture of fermented foods and beverages, especially lactic acid bacteria and yeast. Both are responsible for converting milk into cheese or yogurt, meat into sausage, and vegetables into sauerkraut, wine, bread, and beer.

(Here’s how to get the perfect homemade pizza, according to science: ‘Forget the tomatoes and cheese’)

drunk story

of Yeast for bread, wine and beer, Saccharomyces cerevisiae, which is what this article is about. It was probably domesticated in the earliest agricultural settlements in Asia or the Near East. Archaeological remains, Mesopotamian tablets, and Egyptian papyrus document recipes for making wine or the original beer that was popular in these early civilizations.

Perhaps the oldest archaeological evidence for eating fermented grains comes from the Mesolithic Natufian culture of the Near East, from 12,500 BC to 9,500 BC. C. We can speculate on the “magical” evolution of sugary grape juice An intoxicating and immortal mixture

It happened empirically in the fruit or grain shop and soon became technically dominant, of course by women in the family clan or even the priestly caste.

Many centuries before the Greek feasts witnessed by Plato’s writings, the consumption of fermented beverages was incorporated into mystical rituals and seasonal festivals.

The Gospel itself is the basis of Christianity, referring to these cults that combined bread and wine, the product of the fermentation of bread and wine. Saccharomycesas the axis of the Eucharist ceremony.

In the context of these rituals, the state of intoxication induced by fermented beverages can be interpreted as a state in the first civilization supernatural awareness According to the mythical drinkers of nectar, soma, etc., can connect with the gods. Despite its antiquity and historical weight—no historian can outright deny that many decisions that changed the course of history were likely made while drinking—alcoholic fermentation was not scientifically explained until the 19th century. .

until pasteur came along

The first person to observe yeast in fermented foods was Antoni van Leeuwenhoek (1632-1723). But the hypothesis of the physicist Charles Cagniard de la Tour (1777-1859) and the naturalist Theodor Schwann (1810-1882) was proved, these The hypothesis supporting the active role of these “animals” in the conversion of sugar into alcohol and carbon dioxide was not scientifically proven until Louis Pasteur (1822-1895) became interested in this. biochemical transformation This happens in the production of wine and beer.

Pasteur himself patented a method of beer production with which he intended to surpass the quality of broth produced by Germany’s enemies during the Franco-Prussian War.The application of pure culture techniques developed by Pasteur himself and his German rival Robert Koch (1843-1910), inspired Emil Christian Hansen (1842-1909) from Copenhagen Grape juice was isolated at the Carlsberg factory, where he worked as a microbiologist, to beer yeast.

This yeast is a hybrid yeast Saccharomyces cerevisiae Yeast domesticated and adapted to cold climates, Bayan yeast.The mixture was subsequently named Karlsberg yeast today it has been renamed Pasteur yeast In honor of the father of microbiology.

Fermentation yeast is the most profitable microorganism in the world and is essential for industry Bakery, Cocoa, Wine & Beerand production distilled beverage. It is estimated that in Europe alone we produce 1 million tons of yeast per year for commercial use.

We know your genes

Saccharomyces cerevisiae It was also a model for biology throughout the 20th century, thanks to its tractable cycle of nutrition and sexual reproduction, best suited for easy testing of Mendel’s laws.After all, it is eukaryote – has a true nucleus – which we know best at the genetic and molecular level.

this Complete sequencing of the 16 chromosomes contained in its genomeIn 1996, it was a major comprehensive paper on the subsequent sequencing of the human genome. Although hundreds of millions of years of divergent evolution separated humans from yeast, many physiological functions and cellular biochemical pathways are still well preserved. So much so that geneticist Ira Herskowitz (1943-2003), one of the fathers of yeast cell biology, often used the gemstone phrase “Yeast is a single-celled human being” to answer any doubts about the validity of his model sex, and solved the problem. Ironic, but determined to have any possible discussion about it.

And in the 21st century, using Saccharomyces cerevisiae As a model, he has won three Nobel Prizes: the Hartwell Prize (2001), the Schekman Prize (2013) and the Oshumi Prize (2018). For his work on mechanistic models controlling the cell division cycle (essential for fighting cancer), vesicle trafficking between organelles, and autophagy.

To its importance as a model organism and industrial fermentation we must add that It acts as a probioticits use in the chemical pharmaceutical industry to produce extremely important medicines such as hormones (human insulin) or vaccines (hepatitis B) on an industrial scale and at low cost, or in the production of bioalcohol in clean areas of energy.

antibacterial alcohol

Yeast has existed on Earth for hundreds of millions of years. What were they doing before we domesticated them?

We know they travel on the legs and guts of wasps, flies and other insects, including fruit flies, Drosophila melanogaster

. They survive winter as part of the gut microbiota of these insects.when the time comes ripe fruit or any must be high in sugarVoracious flies and wasps transport the yeast (giant to them, the size of a red blood cell) over great distances and inoculate the fruit with their saliva and legs.

But right there, they ran into a formidable competitor with a faster metabolism: bacteria. Fortunately, nature is very smart, and yeast, as it consumes sugar, converts the sugar into a powerful antimicrobial product: ethanol, a disinfectant and antiseptic that stops bacteria and viruses.

Alcoholic fermentation is therefore a survival strategy that allows these small fungi to compete in their niche. By using them to make beer or wine, humans are just an opportunist who has domesticated this alcoholic fermentation, which is so important in our food culture.

* Victor Jimenez CidProfessor of Microbiology at the Complutense University of Madrid.

** This article was originally published on The Conversation.