Bakers Yeast, Saccharomyces Cerevisiae

by Oliver Meckes EYE OF SCIENCE

Title

Bakers Yeast, Saccharomyces Cerevisiae

Artist

Oliver Meckes EYE OF SCIENCE

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Photograph - Photograph

Description

Baker's yeast is the common name for the strains of yeast commonly used in baking bread and bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae, and is the same species (but a different strain) as the kind commonly used in alcoholic fermentation, which is called brewer's yeast. Baker's yeast is also a single-cell microorganism found on and around the human body. The cells are round, oval or elongated, pseudomycelium formation can occur. The vegetative multiplication takes place by multipolar sprouting, "mother cells" retain a navel-like scar after the division (here yellow). Most Saccharomyces species can ferment a range of sugars (e.g. glucose, sucrose, maltose, raffinose, galactose) to ethanol (alcoholic fermentation); the fermentation metabolism can take place up to approx. 18 vol.% ethanol. In nature, Saccharomyces species mainly occur on the fruits and sap flows of plants. The cultivated yeasts, mostly strains of Saccharomyces cerevisiae, are used in food and beverage production as well as in biotechnology, e.g. enzyme production and biotransformation. Recently, Saccharomyces has also been used in genetic engineering as a host for the expression of foreign genes for the production of special substances (hormones, enzymes, surface antigens). In 1997, the DNA sequence of Saccharomyces cerevisiae was completely decrypted (13 million base pairs, approx. 5600 genes). Scanning electron microscope, magnification 10,000x (at 12x15 cm image size).

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May 19th, 2021

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