Difference between revisions of "Yeast"

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-A '''yeast''' is a single-celled [[fungi|fungus]]. It is related to other fungi that people are more familiar with. These include edible [[mushroom]]s which are available at the local supermarket, common baker’s yeast used to leaven [[bread]], [[mold]]s that ripen blue [[cheese]] as well as molds that produce [[antibiotic]]s for medical and veterinary use. Many consider edible yeast and fungi to be as natural as fruits and vegetables.
-==Yeast Cells==
-Over 600 different species of yeast are known. They are found in association with other microorganisms as part of the normal inhabitants of [[soil]], vegetation, marine and other aqueous environments. Some yeast species are also natural inhabitants of [[man]] and animals. While some species are highly specialized and found only in certain habitats at certain times of the year, other species are generalists and can be isolated from many different sources.
-Baker’s (or brewer's) yeast (''Saccharomyces cerevisiae'') is used to leaven bread throughout the world and it is the type of yeast that people are most familiar with. It is also used in making beer and wine, although sometimes other closely related species such as ''Saccharomyces carlsbergensis'' or ''Saccharomyces bayanus'' are used instead.
-A typical yeast cell is approximately equal in size to a human [[red blood cell]] and is spherical to ellipsoidal in shape. Because it is so very tiny, it takes about 30 billion yeast cells to make up to one gram of compressed baker’s yeast. Yeasts reproduce magnanimously by budding, a process during which a new bud grows from the side of the existing cell wall. This bud eventually breaks away from the mother cell to form a separate daughter cell. Each budding yeast cell, on average, undergoes this budding process 12 to 15 times before it is no longer capable of budding.
-During commercial production, yeast is grown under carefully controlled conditions on a [[sugar]] containing medium typically composed of [[beet]] and [[cane]] molasses. Under ideal growth conditions a yeast cell reproduces every two to three hours. Under anaerobic (devoid of oxygen) conditions the yeast cell will carry out the metabolic process of [[fermentation]] to produce ethanol and carbon dioxide.
-==Other notable yeasts==
-''Schizosacharomyces pombe'' is a yeast first isolated from East Afrian millet beer (''pombe'' is the Swahili word for beer).  However, it is most important as a laboratory experimental organism for the investigation of cell biology.  Sir Paul Nurse won the 2001 Nobel Prize for Physiology and Medicine for his discoveries of how the cell division cycle is regulated in ''S. pombe''. <ref> http://nobelprize.org/nobel_prizes/medicine/laureates/2001/ </ref>
-''Candida albicans'' is a common [[commensal]] yeast which lives on human skin and in the gut.  About 50% of people carry it, with no noticeable effect.  It is most well known as the cause of thrush, although less frequently it can cause nasty oral infections.  In severely immunocompromised patients it can spread through the body and invade vital organs, with a high mortality rate. <ref> http://www.healthscout.com/ency/68/312/main.html </ref>
-==References==
-<references/>
-[[Category:Food and drink]]
-[[Category:Fungi]]
-[[Category:microbiology]]

Difference between revisions of "Yeast"

Revision as of 00:20, September 12, 2007

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