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Why is this yeast a star in life science? Delve into the secrets of Saccharomyces cerevisiae!
Saccharomyces cerevisiae, often called brewer's yeast or baker's yeast, has played an integral role in winemaking, baking and brewing since ancient times. With its origins traced back to the skin of grapes, it is one of the most intensively studied eukaryotic models. How many secrets does this yeast hold?
Saccharomyces comes from the Greek root, meaning "sugar mold", and cerevisiae means "beer" in Latin.
The cells of S. cerevisiae are usually round or oval, 5 to 10 micrometers in diameter, and reproduce by budding. This yeast can initiate many common fermentation processes and provides important assistance in many biological studies, as many key proteins in human biology were discovered through the study of its homologs, including cell cycle proteins, signaling Protein and protein processing enzymes, etc. Notably, S. cerevisiae is the only yeast found to possess Berkeley bodies, cellular structures that play important roles in specific secretory pathways.
Historical BackgroundIn the 19th century, bakers mostly obtained yeast from brewers, which led to the rise of sweet leavened breads such as Imperial "Kaisersemmel". Over time, brewers gradually switched from using S. cerevisiae (top-fermenting yeast) to S. pastorianus (bottom-fermenting yeast).
With the advances in microbiology made by Louis Pasteur, more advanced methods for growing pure strains of bacteria became possible.
In the early 20th century, new production technologies transformed yeast production into a major industrial process, simplifying distribution, reducing unit costs, and playing a major role in the commercialization and commoditization of bread and beer. During World War II, Fleischmann's developed granular active dry yeast for the U.S. military that did not require refrigeration, making the yeast's shelf life longer and more resistant to high temperatures, making it the standard yeast for many U.S. military recipes.
Biological characteristics
In the natural environment, yeast cells are mainly found on ripe fruits, such as grapes. S. cerevisiae can also be found on the bark of oak trees. In social ants during the winter, this yeast can be spread from queen to queen. Such reproduction and growth allow S. cerevisiae to grow at an optimal temperature of about 30 to 35°C.
Growth cycle
S. cerevisiae exists as a single cell and is able to grow in a diploid form under nutrient-rich conditions. When environmental pressure increases, diploid cells can produce four haploid spores through meiosis and then hybridize. Under optimal conditions, the yeast can double its population every 100 minutes, but this growth rate varies depending on the strain and environment.
The reproductive lifespan of the yeast averages about 26 cell divisions, a process that slows down over time when it is not reproductive.
Nutritional requirements
All S. cerevisiae strains were able to grow aerobically on glucose, maltose, and trehalose, but were unable to grow on lactose and cellobiose. They can utilize ammonia and urea as sole nitrogen sources, but are unable to utilize nitrates. These characteristics make S. cerevisiae more flexible in laboratory and industrial applications.
Application in biological research
S. cerevisiae plays the role of a model organism in biological research. The transfer and removal of genes has become the basis of many important experiments. It is also widely used in research such as aging, brain damage and DNA repair. Because of its ease of manipulation and rapid propagation, S. cerevisiae has been used in the development of many biotechnological techniques.
Genome SequencingS. cerevisiae is also known as the first eukaryotic organism to have its genome sequenced, an achievement officially announced on April 24, 1996. This database has become an important resource for studying yeast.
The study of S. cerevisiae is not only crucial to the development of basic science, but also provides new directions for addressing many applied problems in medicine and agriculture. From general fermentation processes to complex gene regulation, will its endless mysteries only be revealed by time?
