Yeast

Why stick yeast with such an outrageously unpronounceable name as Saccharomyces cerevisiae? What is it with biologists that they have to make names so hard to deal with? In this case, you can blame the chemists, because it comes from saccharide referring to the structure of sugar. Saccharomyces roughly translates to sugar fungus.

Services

Saccharomyces cerevisiae is the scientific name of a species of yeast fungus. It is the best known out of the 1,500 species of unicellular fungi. Each Saccharomyces cell by itself is microscopic (about 5% of the width of a human hair). It is commonly used in the production of leavened bread, in beer brewing and in wine-making. These process make use of the fact that S.cerevisiae breaks down sugars into carbon dioxide and alcohol (fermentation). Humans have been utilitising this service for millennia. That should be enough for entry to the hall of fame. But yeast gives us so much more.

Saccharomyces cerevisiae is a eukaryote just like humans are. This means any cell or organism that possesses a clearly defined nucleus. The eukaryotic cell has a nuclear membrane that surrounds the nucleus. The nucleus contains chromosomes which are bodies containing genetic material. Yeast has been a powerful model organism for understanding aspects of  human biology and disease. It has been used to test out the effects of various drugs at the cellular level.

And in addition to that service, it has also been used as a drug manufacturing machine.

[Saccaromyces] is also used as a “cell-factory” to produce commercially important proteins (such as insulin, human serum albumin, hepatitis vaccines). About 20% of biopharmaceuticals are produced from yeast, the advantage being that, as a eurkaryotic model, this enables production and proper folding of many human proteins. ¹

Yeast has been the model organism used in Nobel prize winning research 11 times in the period 2000 - 2021. It has been used in cancer research and cell ageing studies. It has also been used to make bioethanol fuel and as a nutritional supplement in diets.

Another feather in yeast's cap, so to speak, is this new service provided to humans

Flowers of the hop plant provide both bitterness and “hoppy” flavor to beer. Hops are, however, both a water and energy intensive crop and vary considerably in essential oil content, making it challenging to achieve a consistent hoppy taste in beer. Here, we report that brewer’s yeast can be engineered to biosynthesize aromatic monoterpene molecules that impart hoppy flavor to beer by incorporating recombinant DNA derived from yeast, mint, and basil.²

Al Capp, the Shmoo and yeast

Al Capp (creator of the Li'l Abner cartoon) invented a character called the "shmoo". In the cartoon , shmoos wanted nothing more than to be food for humans. With typical cartoon whimsy, shmoos could be many different foods - eggs, milk, meat, occasionally cake. They were versatile and generous with their services to humans.

According to Capp, in an article in 1949

"I was driving from New York City to my farm in New Hampshire. The top of my car was down, and on either side of me I could see the lush and lovely New England countryside... It was the good earth at its generous summertime best, offering gifts to all. And the thought that came to me was this: Here we have this great and good and generous thing—the Earth. It's eager to give us everything we need. All we have to do is just let it alone, just be happy with it."

Biologists celebrated this imaginary creature by calling a yeast cell in a certain state of reproduction, a "shmoo cell" as a tribute to the usefulness and versatility of the shmoo - service provider "par excellence"

Let's have a round of applause for all the services yeast has provided us with.

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Summary of services provided for us

• Used for leavening for bread making
• Makes beer brewing possible
• Used to add alcohol in the wine making process
• Used as a model cell to study  the effects of drugs at the cellular level
• Used as a model organism in a variety of scientific experiments investigating human disease
• Used to manufacture various pharmaceutical products.
• Used to make bioethanol
• Used to make a nutritional supplement

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Threats to the services?

Despite being one of the most studied organisms on the planet in terms of genetics and biochemistry, relatively little investigation has been carried out on S. cerevisiae in the wild. As this yeast has been cultivated in laboratories since the 1850s, it has departed somewhat genetically from other wild relatives. Recent surveys taken in the past decade have detected no sign of scarcity of yeast populations, so there is not considered to be any significant threat to the species.

What can we do to retain these services?

N/A

Dig deeper

• Why use yeast in research?
• The Wild Frontier of Model Organism Research
• What Are Some Common Uses of Yeast?