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Saccharomyces cerevisiae
S. cerevisiae under DIC microscopy
Scientific classification
Kingdom: Fungi
Phylum: Ascomycota
Subphylum: Saccharomycotina
Class: Saccharomycetes
Order: Saccharomycetales
Family: Saccharomycetaceae
Genus: Saccharomyces
Species: S. cerevisiae
Binomial name
Saccharomyces cerevisiae
Meyen ex E.C. Hansen
.Saccharomyces cerevisiae is a species of budding yeast.^ There are about 7 species, the most common one is Saccharomyces cerevisiae .
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

.It is perhaps the most useful yeast owing to its use since ancient times in baking and brewing.^ In fact, it is the originally isolated Champagne yeast and one of the most widely used strains in Champagne.

^ I made the wine my own way, in my own time, but pretty much used their ingredients (except yeast and the smoked oak).

^ Most recipes use 20-25% agave nectar, a lemon or two, some nutrients, and any wine yeast.

.It is believed that it was originally isolated from the skins of grapes (one can see the yeast as a component of the thin white film on the skins of some dark-colored fruits such as plums; it exists among the waxes of the cuticle).^ An old-timer told me that one - deer won't jump a fence higher than themselves that they can't see through, so let some wild grapes grow on the fence and they'll stay out.

^ In fact, it is the originally isolated Champagne yeast and one of the most widely used strains in Champagne.

^ There are several variants of the Malay Apple, most notable in fruit size and color - red fruit is usual but variegated varieties and a rare albino exist.

.It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology, much like Escherichia coli as the model prokaryote.^ One of the most striking alterations of cell-walls is that termed carbonization, in which the substance gradually turns black, hard and brittle, as if charred - e.g.

^ Their nucleus like that of other eukaryotic organisms contains a nucleolus and several chromosomes that are bound by a nuclear membrane.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ Since it is possible to view more than 5 organisms, be sure to reset until you have studied at least one organism from each kingdom.

It is the microorganism behind the most common type of fermentation. S. cerevisiae cells are round to ovoid, 5–10 micrometres in diameter. .It reproduces by a division process known as budding.^ In the process of budding the nucleus divides apparently by a process of direct division.

.Many proteins important in human biology were first discovered by studying their homologs in yeast; these proteins include cell cycle proteins, signaling proteins, and protein-processing enzymes.^ Other important model fungi are Aspergillus nidulans and the yeasts, Saccaromyces cerevisiae and Schizosaccharomyces pombe , each of which has a long history of use to investigate issues in eukaryotic cell biology and genetics , such as cell cycle regulation, chromatin structure, and gene regulation .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ His observation was important because he was the first to incriminate a microorganism as the cause of human infection.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ This phylum includes morels , a few mushrooms and truffles , single-celled yeasts (e.g., of t he genera Saccharomyces , Kluyveromyces , Pichia , and Candida ), and many filamentous fungi living as saprotrophs, parasites, and mutualistic symbionts.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

The petite mutation in S. cerevisiae is of particular interest.
.Antibodies against S. cerevisiae are found in 60–70% of patients with Crohn's disease and 10–15% of patients with Ulcerative colitis.^ Approximately 60% of patients with primary infections are asymptomatic, 40% have mild to acute pulmonary disease and approximately 0.5% develop serious disease.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

"Saccharomyces" derives from Latinized Greek and means "sugar mold" or "sugar fungus", saccharo- being the combining form "sugar-" and myces being "fungus". cerevisiae comes from Latin and means "of beer". Other names for the organism are:
  • S. cerevisiae short form of the scientific name
  • Brewer's yeast (the apostrophe may be after the s or missing), though other species are also used in brewing
  • Ale yeast
  • Top-fermenting yeast
  • Baker's yeast (the apostrophe may be after the s or missing)
  • Budding yeast
.This species is also the main source of nutritional yeast and yeast extract.^ Main article: Antibiotics Many species produce metabolites that are major sources of pharmacologically active drugs.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

Contents

Biology

Life cycle

.There are two forms in which yeast cells can survive and grow: haploid and diploid.^ The cytology of these forms is very little known; Dangeard states that there is a fusion of two nuclei in the chlamydospore, but this requires confirmation .

^ Some species grow as single-celled yeasts that reproduce by budding or binary fission .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ In Zygosaccharomyces described by Barker (1901) we have a form of the usual sprouting type, but here again there is a fusion of two cells to form a sporangium.

.The haploid cells undergo a simple life cycle of mitosis and growth, and under conditions of high stress will generally simply die.^ Life-history always very simple, no wellmarked alternation of generations; basidium borne directly on the mycelium.

^ When the zygospore germinates, it undergoes meiosis , generating new haploid hyphae, which may then form asexual sporangiospores .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ Most fungi have both a haploid and diploid stage in their life cycles.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

.The diploid cells (the preferential 'form' of yeast) similarly undergo a simple life cycle of mitosis and growth, but under conditions of stress can undergo sporulation, entering meiosis and producing a variety of haploid spores, which can proceed on to mate.^ Coccidioides differ from Malbranchea by forming spherules containing endospores under the appropriate conditions.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ Moulds consist of those fungi that grow in a filamentous form, whereas yeasts are characterized by solitary cells that reproduce by budding.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ Under some conditions, occasional isolates of Madurella mycetomatis form phialides having collarettes.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

Nutritional requirements

All strains of S. cerevisiae can grow aerobically on glucose, maltose, and trehalose and fail to grow on lactose and cellobiose. However, growth on other sugars is variable. It was shown that galactose and fructose were two of the best fermenting sugars. .The ability of yeasts to use different sugars can differ depending on whether they are grown aerobically or anaerobically.^ I'm assuming you are using different yeasts for beers, ales and wines.

^ They contain glucose, fructose, and sucrose sugars and are eaten raw, made into refreshing drinks, or dried for later use.

^ The yeast-conidia, which bud off from the conidia or their resulting mycelium when sown in nutrient solutions, are developed in successive crops by budding exactly as in the yeast plant, but they cannot ferment sugar solutions.

Some strains cannot grow anaerobically on sucrose and trehalose.
All strains can utilize ammonia and urea as the sole nitrogen source, but cannot utilize nitrate since they lack the ability to reduce them to ammonium ions. They can also utilize most amino acids, small peptides and nitrogen bases as a nitrogen source. Histidine, Glycine, Cystine and Lysine are however, not readily utilized. S. cerevisiae does not excrete proteases so extracellular protein cannot be metabolized.
.Yeasts also have a requirement for phosphorus, which is assimilated as a dihydrogen phosphate ion, and sulfur, which can be assimilated as a sulfate ion or as organic sulfur compounds like the amino acids methionine and cysteine.^ Proprietary yeast nutrients usually contain DAP (diammonium phosphate), which supplies nitrogen and phosphorus; urea, which supplies nitrogen; citric (and perhaps other) acid; trace amounts of biotin; and yeast hulls.

^ Fungi are carbon heterotrophs therefore they require preformed organic compounds as carbon sources.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ With animals: Fungi lack chloroplasts and are heterotrophic organisms, requiring preformed organic compounds as energy sources.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

.Some metals like magnesium, iron, calcium, zinc also are required for good growth of the yeast.^ Seriously does yeast just not like some people?

^ Some fungi have yeast like and mould like forms.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

Mating

.Yeast has two mating types, a and α (alpha), which show primitive aspects of sex differentiation, and are hence of great interest.^ The two kinds of 4, thalli Blakeslee considers to have a differentiation 5, of the nature of sex and he distinguishes them as (+) and (-) forms; the former being usually distinguished by a somewhat greater luxuriance of growth.

^ Fleischmann's Active Dry Yeast comes in two types .

.For more information on the biological importance of these two cell types, where they come from (from a molecular biology point of view), and details of the process of mating type switching, see the main article.^ See the blogspot site for more information.

^ Since our theme this grading period is the Everglades, both of these articles help us see how we as humans impact our environment, sometimes for the worst.

^ Then, click the second link to view cytoplasmic streaming in these living cells.

Cell cycle

.Growth in yeast is synchronised with the growth of the bud, which reaches the size of the mature cell by the time it separates from the parent cell.^ Some species grow as single-celled yeasts that reproduce by budding or binary fission .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ Moulds consist of those fungi that grow in a filamentous form, whereas yeasts are characterized by solitary cells that reproduce by budding.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ A typical yeast is able to develop b new cells by budding when submerged in a saccharine solution, and to ferment the sugar - i.e.

.In rapidly growing yeast cultures, all the cells can be seen to have buds since bud formation occupies the whole cell cycle.^ Some species grow as single-celled yeasts that reproduce by budding or binary fission .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ Fertile cells; at a 2 the brachy forms, and before the passage of a nucleus from formation of teleutospores in the adjoining cell is seen.

^ The etiologic agent grows as a large yeast within the giant cells as well as small cells that are typical of those seen in histoplasmosis capsulati.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

Both mother and daughter cell can initiate bud formation before cell separation has occurred. .In yeast cultures which are growing more slowly, cells lacking buds can be seen and bud formation only occupies a part of the cell cycle.^ In some people the yeast grows more actively and causes a red, itchy, scaling rash.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ Fertile cells; at a 2 the brachy forms, and before the passage of a nucleus from formation of teleutospores in the adjoining cell is seen.

^ The etiologic agent grows as a large yeast within the giant cells as well as small cells that are typical of those seen in histoplasmosis capsulati.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

.The cell cycle in yeast normally consists of the following stages—G1, S, G2 and M—which are the normal stages of mitosis.^ VVC is caused by an overabundance or overgrowth of yeast cells, primarily Candida albicans , that normally colonize the vagina.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ Moulds consist of those fungi that grow in a filamentous form, whereas yeasts are characterized by solitary cells that reproduce by budding.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

Yeast in biological research

A model organism

When researchers look for an organism to use in their studies, they look for several traits. Among these are size, generation time, accessibility, manipulation, genetics, conservation of mechanisms, and potential economic benefit. .The yeast species S. pombe and S. cerevisiae are both well studied; these two species diverged approximately 300 to 600 million years before present, and are significant tools in the study of DNA damage and repair mechanisms.^ Among these, three well-known pathogenic species are Bipolaris spicifera , Bipolaris australiensis , and Bipolaris hawaiiensis .
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ We will also use this time to continue learning about energy, as well as review information presented earlier this year.

^ However, little is known of the true biodiversity of Kingdom Fungi, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

[1]
The alpha-factor of S. cerevisiae, has been compared to the liphophilic peptide created by the fungus Tremella mesenterica.[2]
S. cerevisiae has developed as a model organism because it scores favorably on a number of these criteria.
.
  • As a single celled organism S. cerevisiae is small with a short generation time (doubling time 1.5–2 hours @ 30 °C) and can be easily cultured.^ Baker's yeast or Saccharomyces cerevisiae , a single-celled fungus, is used to make bread and other wheat-based products, such as pizza dough and dumplings .
    • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

    .These are all positive characteristics in that they allow for the swift production and maintenance of multiple specimen lines at low cost.
  • S. cerevisiae can be transformed allowing for either the addition of new genes or deletion through homologous recombination.^ These sporangiospores allow the fungus to rapidly disperse and germinate i nto new genetically identical haploid fungal mycelia.
    • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

    ^ To thaw them, allow a full 24 hours so they thaw through and through and at least come close to assuming room temperature.

    ^ The only physiological peculiarity exhibited in common by all spores is that they germinate and initiate the production of a new fungus-plant.

    .Furthermore, The ability to grow S. cerevisiae as a haploid simplifies the creation of gene knockouts strains.
  • As a eukaryote, S. cerevisiae shares the complex internal cell structure of plants and animals without the high percentage of non-coding DNA that can confound research in higher eukaryotes.
  • S. cerevisiae research had a strong economic driver, at least initially, as a result of its established use in industry (e.g.^ For the plant, we will use virtual cells.

    ^ Other important model fungi are Aspergillus nidulans and the yeasts, Saccaromyces cerevisiae and Schizosaccharomyces pombe , each of which has a long history of use to investigate issues in eukaryotic cell biology and genetics , such as cell cycle regulation, chromatin structure, and gene regulation .
    • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

    ^ With other eukaryotes: As other eukaryotes, fungal cells contain membrane-bound nuclei with chromosomes that contain DNA with noncoding regions called introns and coding regions called exons .
    • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

    beer, bread and wine fermentation).

Genome sequencing

S. cerevisiae was the first eukaryotic genome that was completely sequenced.[3] The genome sequence was released in the public domain on April 24, 1996. Since then, regular updates have been maintained at the Saccharomyces Genome Database (SGD). This database is a highly annotated and cross-referenced database for yeast researchers. .Another important S. cerevisiae database is maintained by the Munich Information Center for Protein Sequences (MIPS).^ Munich Information Center for Protein Sequences (MIPS) .
  • Selected Web Resources on Natural Sciences 25 September 2009 1:53 UTC chem.saratov.ru [Source type: Academic]

The genome is composed of about 12,156,677 base pairs and 6,275 genes, compactly organized on 16 chromosomes. .Only about 5,800 of these are believed to be true functional genes.^ However, little is known of the true biodiversity of Kingdom Fungi, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

It is estimated that yeast shares about 23% of its genome with that of humans .

Other tools in yeast research

.The availability of the S. cerevisiae genome sequence and the complete set of deletion mutants has further enhanced the power of S. cerevisiae as a model for understanding the regulation of eukaryotic cells.^ Other important model fungi are Aspergillus nidulans and the yeasts, Saccaromyces cerevisiae and Schizosaccharomyces pombe , each of which has a long history of use to investigate issues in eukaryotic cell biology and genetics , such as cell cycle regulation, chromatin structure, and gene regulation .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

A project underway to analyze the genetic interactions of all double deletion mutants through Synthetic genetic array analysis will take this research one step further.
Approaches have been developed by yeast scientists which can be applied in many different fields of biological and medicinal science. .These include Yeast two-hybrid for studying protein interactions and tetrad analysis.^ The study, published in the journal of the Federation of the American Societies for Experimental Biology ( FASEB Journal ), found that resveratrol blocks two major proteins that trigger inflammation.

Yeast in commercial applications

Top-fermenting yeast

.Saccharomyces cerevisiae is known as top-fermenting yeast, so called because during the fermentation process its hydrophobic surface causes the flocs to adhere to CO2 and rise to the top of the fermentation vessel.^ Because S. cerevisiae is top fermenting, it the active yeast can be .

^ The fruit will rise to the top, pushed there by the CO 2 created by the yeast.

^ Saccharomyces cerevisiae is the yeast found in ale barm.

.It is one of the major types of yeast used in the brewing of ale, along with Saccharomyces pastorianus which is used in the brewing of lager.^ Baker's yeast or Saccharomyces cerevisiae , a single-celled fungus, is used to make bread and other wheat-based products, such as pizza dough and dumplings .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ I'm assuming you are using different yeasts for beers, ales and wines.

^ Lager yeast would be less useful as a leavening.

.Top-fermenting yeasts are fermented at higher temperatures than lager yeasts and the resulting ales have a different flavor than the same beverage fermented with a lager yeast.^ Modern bread yeasts are different varieties of the same species as ale .

^ I'm assuming you are using different yeasts for beers, ales and wines.

^ Ales are top fermenting and are fairly light tasting.

."Fruity esters" may be formed if the ale yeast undergoes temperatures near 21 °C (70 ° Fahrenheit), or if the fermentation temperature of the beverage fluctuates during the process.^ Yeast species of the genus Saccharomyces are also used to produce alcoholic beverages through fermentation.
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ When the zygospore germinates, it undergoes meiosis , generating new haploid hyphae, which may then form asexual sporangiospores .
  • Fungi (Kingdom) 25 September 2009 1:53 UTC zipcodezoo.com [Source type: Academic]

^ Under other conditions, of which the temperature is an important one, the nucleus in the yeast-cell divides, and each daughter-nucleus again, and four spores are formed in the mother cell, a process obviously comparable to the typical development of ascospores in an ascus.

Lager yeast normally ferments at a temperature of approximately 5 °C (40 °Fahrenheit), where ale yeast becomes dormant. Lager yeast can be fermented at a higher temperature normally used for ale yeast, and this application is often used in a beer style known as "steam beer".

Uses in aquaria

.Owing to the high cost of commercial CO2 cylinder systems, CO2 injection by yeast is one of the most popular DIY approaches followed by aquaculturists for providing CO2 to underwater aquatic plants.^ In fact, it is the originally isolated Champagne yeast and one of the most widely used strains in Champagne.

^ The fungi causing systemic mycoses are either filamentous, or one of several unicellular yeasts.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

^ Most of the dimorphic fungi, yeasts and dangerous opportunistic pathogens are capable of causing systemic mycoses.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

.The yeast culture is generally maintained in plastic bottles and typical systems provide one bubble every 3–7 seconds.^ The fungi causing systemic mycoses are either filamentous, or one of several unicellular yeasts.
  • Aquatic Pathogens-Fungi 27 January 2010 23:54 UTC www.env.gov.bc.ca [Source type: Academic]

.Various approaches have been devised to allow proper absorption of the gas into the water.^ Regular science classes read how the EPA allowed polluted water to flow into Lake Okeechobee.

See also

References

Line notes

  1. ^ Jac A. Nickoloff and Merl F. Hoekstra. 1998
  2. ^ C. Michael Hogan. 2008
  3. ^ Goffeau A, Barrell BG, Bussey H, Davis RW, Dujon B, Feldmann H, Galibert F, Hoheisel JD, Jacq C, Johnston M, Louis EJ, Mewes HW, Murakami Y, Philippsen P, Tettelin H, Oliver SG (Oct 1996). "Life with 6000 genes". Science (New York, N.Y.) 274 (5287): 546, 563–567. doi:10.1126/science.274.5287.546. ISSN 0036-8075. PMID 8849441.  edit

External links

CO2 injection by yeast for planted aquaria


Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Saccharomyces cerevisiae

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Fungi
Divisio: Ascomycota
Subphylum: Saccharomycotina
Classis: Saccharomycetes
Ordo: Saccharomycetales
Familia: Saccharomycetaceae
Genus: Saccharomyces
Species: Saccharomyces cerevisiae

Name

Saccharomyces cerevisiae Meyen ex E.C. Hansen, 1883

References

Vernacular names

Български: Дрожди
Deutsch: Bäckerhefe
English: baker's yeast, brewer's yeast, budding yeast
Français: levure de bière, levure de boulanger, levure boulangère, levure à bourgeon, levure bourgeonnante
Nederlands: biergist, bakkersgist, wijngist, brouwersgist, broodgist
日本語: 出芽酵母
Русский: Пивоваренные дрожжи
中文: 釀酒酵母

Citable sentences

Up to date as of December 11, 2010

Here are sentences from other pages on Fungus, which are similar to those in the above article.








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