Yeast

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Yeast
Yeast of the species Saccharomyces cerevisiae
Cross-sectional labelled diagram of a typical yeast cell
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Phyla and Subphyla
Ascomycota p. p. Saccharomycotina (true yeasts) Taphrinomycotina p. p. Schizosaccharomycetes (fission yeasts) Basidiomycota p. p. Agaricomycotina p. p. Tremellomycetes Pucciniomycotina p. p. Microbotryomycetes

Yeasts are eukaryotic single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and 1,500 species are currently identified. They are estimated to constitute 1% of all described fungal species. Yeasts are unicellular organisms which evolved from multicellular ancestors, with some species having the ability to develop multicellular characteristics by forming strings of connected budding cells known as pseudohyphae or false hyphae. Yeast sizes vary greatly, depending on species and environment, typically measuring 3–4 µm in diameter, although some yeasts can grow to 40 µm in size. Most yeasts reproduce asexually by mitosis, and many do so by the asymmetric division process known as budding.

Yeasts, with their single-celled growth habit, can be contrasted with molds, which grow hyphae. Fungal species that can take both forms (depending on temperature or other conditions) are called dimorphic fungi ("dimorphic" means "having two forms").

By fermentation, the yeast species Saccharomyces cerevisiae converts carbohydrates to carbon dioxide and alcohols – for thousands of years the carbon dioxide has been used in baking and the alcohol in alcoholic beverages. It is also a centrally important model organism in modern cell biology research, and is one of the most thoroughly researched eukaryotic microorganisms. Researchers have used it to gather information about the biology of the eukaryotic cell and ultimately human biology. Other species of yeasts, such as Candida albicans, are opportunistic pathogens and can cause infections in humans. Yeasts have recently been used to generate electricity in microbial fuel cells, and produce ethanol for the biofuel industry.

Yeasts do not form a single taxonomic or phylogenetic grouping. The term "yeast" is often taken as a synonym for Saccharomyces cerevisiae, but the phylogenetic diversity of yeasts is shown by their placement in two separate phyla: the Ascomycota and the Basidiomycota. The budding yeasts ("true yeasts") are classified in the order Saccharomycetales, within the phylum Ascomycota.

History

The word "yeast" comes from Old English gist, gyst, and from the Indo-European root yes-, meaning "boil", "foam", or "bubble". Yeast microbes are probably one of the earliest domesticated organisms. Archaeologists digging in Egyptian ruins found early grinding stones and baking chambers for yeast-raised bread, as well as drawings of 4,000-year-old bakeries and breweries. In 1680, Dutch naturalist Anton van Leeuwenhoek first microscopically observed yeast, but at the time did not consider them to be living organisms, but rather globular structures as researchers were doubtful whether yeasts were algae or fungi. Theodor Schwann recognized them as fungi in 1837.

In 1857, French microbiologist Louis Pasteur showed that by bubbling oxygen into the yeast broth, cell growth could be increased, but fermentation was inhibited – an observation later called the "Pasteur effect". In the paper "Mémoire sur la fermentation alcoolique," Pasteur proved that alcoholic fermentation was conducted by living yeasts and not by a chemical catalyst.

By the late 18th century two yeast strains used in brewing had been identified: Saccharomyces cerevisiae (top-fermenting yeast) and S. carlsbergensis (bottom-fermenting yeast). S. cerevisiae has been sold commercially by the Dutch for bread-making since 1780; while, around 1800, the Germans started producing S. cerevisiae in the form of cream. In 1825, a method was developed to remove the liquid so the yeast could be prepared as solid blocks. The industrial production of yeast blocks was enhanced by the introduction of the filter press in 1867. In 1872, Baron Max de Springer developed a manufacturing process to create granulated yeast, a technique that was used until the first World War. In the United States, naturally occurring airborne yeasts were used almost exclusively until commercial yeast was marketed at the Centennial Exposition in 1876 in Philadelphia, where Charles L. Fleischmann exhibited the product and a process to use it, as well as serving the resultant baked bread.

The mechanical refrigerator (first patented in the 1850s in Europe) liberated brewers and winemakers from seasonal constraints for the first time and allowed them to exit cellars and other earthen environments. For John Molson, who made his livelihood in Montreal prior to the development of the fridge, the brewing season lasted from September through to May. The same seasonal restrictions formerly governed the distiller's art.

Nutrition and growth

Yeasts are chemoorganotrophs, as they use organic compounds as a source of energy and do not require sunlight to grow. Carbon is obtained mostly from hexose sugars, such as glucose and fructose, or disaccharides such as sucrose and maltose. Some species can metabolize pentose sugars such as ribose, alcohols, and organic acids. Yeast species either require oxygen for aerobic cellular respiration (obligate aerobes) or are anaerobic, but also have aerobic methods of energy production (facultative anaerobes). Unlike bacteria, no known yeast species grow only anaerobically (obligate anaerobes). Most yeasts grow best in a neutral or slightly acidic pH environment.

Yeasts vary in regard to the temperature range in which they grow best. For example, Leucosporidium frigidum grows at −2 to 20 °C (28 to 68 °F), Saccharomyces telluris at 5 to 35 °C (41 to 95 °F), and Candida slooffi at 28 to 45 °C (82 to 113 °F). The cells can survive freezing under certain conditions, with viability decreasing over time.

In general, yeasts are grown in the laboratory on solid growth media or in liquid broths. Common media used for the cultivation of yeasts include potato dextrose agar or potato dextrose broth, Wallerstein Laboratories nutrient agar, yeast peptone dextrose agar, and yeast mould agar or broth. Home brewers who cultivate yeast frequently use dried malt extract and agar as a solid growth medium. The antibiotic cycloheximide is sometimes added to yeast growth media to inhibit the growth of Saccharomyces yeasts and select for wild/indigenous yeast species. This will change the yeast process.

The appearance of a white, thready yeast, commonly known as kahm yeast, is often a byproduct of the lactofermentation (or pickling) of certain vegetables, usually the result of exposure to air. Although harmless, it can give pickled vegetables a bad flavor and must be removed regularly during fermentation.

Ecology

Yeasts are very common in the environment, and are often isolated from sugar-rich materials. Examples include naturally occurring yeasts on the skins of fruits and berries (such as grapes, apples, or peaches), and exudates from plants (such as plant saps or cacti). Some yeasts are found in association with soil and insects. The ecological function and biodiversity of yeasts are relatively unknown compared to those of other microorganisms. Yeasts, including Candida albicans, Rhodotorula rubra, Torulopsis and Trichosporon cutaneum, have been found living in between people's toes as part of their skin flora. Yeasts are also present in the gut flora of mammals and some insects and even deep-sea environments host an array of yeasts.

An Indian study of seven bee species and 9 plant species found 45 species from 16 genera colonise the nectaries of flowers and honey stomachs of bees. Most were members of the genus Candida; the most common species in honey stomachs was Dekkera intermedia and in flower nectaries, Candida blankii. Yeast colonising nectaries of the stinking hellebore have been found to raise the temperature of the flower, which may aid in attracting pollinators by increasing the evaporation of volatile organic compounds. A black yeast has been recorded as a partner in a complex relationship between ants, their mutualistic fungus, a fungal parasite of the fungus and a bacterium that kills the parasite. The yeast has a negative effect on the bacteria that normally produce antibiotics to kill the parasite, so may affect the ants' health by allowing the parasite to spread.

Certain strains of some species of yeasts produce proteins called yeast killer toxins that allow them to eliminate competing strains. This can cause problems for winemaking but could potentially also be used to advantage by using killer toxin-producing strains to make the wine. Yeast killer toxins may also have medical applications in treating yeast infections (see "Pathogenic yeasts" section below).

Marine yeasts, defined as the yeasts that are isolated from marine environments, are able to grow better on a medium prepared using seawater rather than freshwater. The first marine yeasts were isolated by Bernhard Fischer in 1894 from the Atlantic Ocean, and those were identified as Torula sp. and Mycoderma sp. Following this discovery, various other marine yeasts have been isolated from around the world from different sources, including seawater, seaweeds, marine fish and mammals. Among these isolates, some marine yeasts originated from terrestrial habitats (grouped as facultative marine yeast), which were brought to and survived in marine environments. The other marine yeasts were grouped as obligate or indigenous marine yeasts, which confine to marine habitats. However, no sufficient evidence has been found to explain the indispensability of seawater for obligate marine yeasts. It has been reported that marine yeasts are able to produce many bioactive substances, such as amino acids, glucans, glutathione, toxins, enzymes, phytase and vitamins with potential application in the food, pharmaceutical, cosmetic and chemical industries as well as for marine culture and environmental protection. Marine yeast was successfully used to produce bioethanol using seawater-based media which will potentially reduce the water footprint of bioethanol.

Reproduction

The yeast cell's life cycle:

1. Budding
2. Conjugation
3. Spore

Yeasts, like all fungi, may have asexual and sexual reproductive cycles. The most common mode of vegetative growth in yeast is asexual reproduction by budding, where a small bud (also known as a bleb or daughter cell) is formed on the parent cell. The nucleus of the parent cell splits into a daughter nucleus and migrates into the daughter cell. The bud then continues to grow until it separates from the parent cell, forming a new cell. The daughter cell produced during the budding process is generally smaller than the mother cell. Some yeasts, including Schizosaccharomyces pombe, reproduce by fission instead of budding, and thereby creating two identically sized daughter cells.

In general, under high-stress conditions such as nutrient starvation, haploid cells will die; under the same conditions, however, diploid cells can undergo sporulation, entering sexual reproduction (meiosis) and producing a variety of haploid spores, which can go on to mate (conjugate), reforming the diploid.

The haploid fission yeast Schizosaccharomyces pombe is a facultative sexual microorganism that can undergo mating when nutrients are limiting. Exposure of S. pombe to hydrogen peroxide, an agent that causes oxidative stress leading to oxidative DNA damage, strongly induces mating and the formation of meiotic spores. The budding yeast Saccharomyces cerevisiae reproduces by mitosis as diploid cells when nutrients are abundant, but when starved, this yeast undergoes meiosis to form haploid spores. Haploid cells may then reproduce asexually by mitosis. Katz Ezov et al. presented evidence that in natural S. cerevisiae populations clonal reproduction and selfing (in the form of intratetrad mating) predominate. In nature, mating of haploid cells to form diploid cells is most often between members of the same clonal population and out-crossing is uncommon. Analysis of the ancestry of natural S. cerevisiae strains led to the conclusion that out-crossing occurs only about once every 50,000 cell divisions. These observations suggest that the possible long-term benefits of outcrossing (e.g. generation of diversity) are likely to be insufficient for generally maintaining sex from one generation to the next. Rather, a short-term benefit, such as recombinational repair during meiosis, may be the key to the maintenance of sex in S. cerevisiae. 

Some pucciniomycete yeasts, in particular species of Sporidiobolus and Sporobolomyces, produce aerially dispersed, asexual ballistoconidia.

Uses

The useful physiological properties of yeast have led to their use in the field of biotechnology. Fermentation of sugars by yeast is the oldest and largest application of this technology. Many types of yeasts are used for making many foods: baker's yeast in bread production, brewer's yeast in beer fermentation, and yeast in wine fermentation and for xylitol production. So-called red rice yeast is actually a mold, Monascus purpureus. Yeasts include some of the most widely used model organisms for genetics and cell biology.

Alcoholic beverages

Alcoholic beverages are defined as beverages that contain ethanol (C₂H₅OH). This ethanol is almost always produced by fermentation – the metabolism of carbohydrates by certain species of yeasts under anaerobic or low-oxygen conditions. Beverages such as mead, wine, beer, or distilled spirits all use yeast at some stage of their production. A distilled beverage is a beverage containing ethanol that has been purified by distillation. Carbohydrate-containing plant material is fermented by yeast, producing a dilute solution of ethanol in the process. Spirits such as whiskey and rum are prepared by distilling these dilute solutions of ethanol. Components other than ethanol are collected in the condensate, including water, esters, and other alcohols, which (in addition to that provided by the oak in which it may be aged) account for the flavour of the beverage.

Beer

Yeast ring used by Swedish farmhouse brewers in the 19th century to preserve yeast between brewing sessions.

Bubbles of carbon dioxide forming during beer-brewing

 

Brewing yeasts may be classed as "top-cropping" (or "top-fermenting") and "bottom-cropping" (or "bottom-fermenting"). Top-cropping yeasts are so called because they form a foam at the top of the wort during fermentation. An example of a top-cropping yeast is Saccharomyces cerevisiae, sometimes called an "ale yeast". Bottom-cropping yeasts are typically used to produce lager-type beers, though they can also produce ale-type beers. These yeasts ferment well at low temperatures. An example of bottom-cropping yeast is Saccharomyces pastorianus, formerly known as S. carlsbergensis. 

Decades ago, taxonomists reclassified S. carlsbergensis (uvarum) as a member of S. cerevisiae, noting that the only distinct difference between the two is metabolic. Lager strains of S. cerevisiae secrete an enzyme called melibiase, allowing them to hydrolyse melibiose, a disaccharide, into more fermentable monosaccharides. Top- and bottom-cropping and cold- and warm-fermenting distinctions are largely generalizations used by laypersons to communicate to the general public.

The most common top-cropping brewer's yeast, S. cerevisiae, is the same species as the common baking yeast. Brewer's yeast is also very rich in essential minerals and the B vitamins (except B₁₂). However, baking and brewing yeasts typically belong to different strains, cultivated to favour different characteristics: baking yeast strains are more aggressive, to carbonate dough in the shortest amount of time possible; brewing yeast strains act more slowly but tend to produce fewer off-flavours and tolerate higher alcohol concentrations (with some strains, up to 22%). 

Dekkera/Brettanomyces is a genus of yeast known for its important role in the production of 'lambic' and specialty sour ales, along with the secondary conditioning of a particular Belgian Trappist beer. The taxonomy of the genus Brettanomyces has been debated since its early discovery and has seen many reclassifications over the years. Early classification was based on a few species that reproduced asexually (anamorph form) through multipolar budding. Shortly after, the formation of ascospores was observed and the genus Dekkera, which reproduces sexually (teleomorph form), was introduced as part of the taxonomy. The current taxonomy includes five species within the genera of Dekkera/Brettanomyces. Those are the anamorphs Brettanomyces bruxellensis, Brettanomyces anomalus, Brettanomyces custersianus, Brettanomyces naardenensis, and Brettanomyces nanus, with teleomorphs existing for the first two species, Dekkera bruxellensis and Dekkera anomala. The distinction between Dekkera and Brettanomyces is arguable, with Oelofse et al. (2008) citing Loureiro and Malfeito-Ferreira from 2006 when they affirmed that current molecular DNA detection techniques have uncovered no variance between the anamorph and teleomorph states. Over the past decade, Brettanomyces spp. have seen an increasing use in the craft-brewing sector of the industry, with a handful of breweries having produced beers that were primarily fermented with pure cultures of Brettanomyces spp. This has occurred out of experimentation, as very little information exists regarding pure culture fermentative capabilities and the aromatic compounds produced by various strains. Dekkera/Brettanomyces spp. have been the subjects of numerous studies conducted over the past century, although a majority of the recent research has focused on enhancing the knowledge of the wine industry. Recent research on eight Brettanomyces strains available in the brewing industry focused on strain-specific fermentations and identified the major compounds produced during pure culture anaerobic fermentation in wort.

Wine

Yeast is used in winemaking, where it converts the sugars present (glucose and fructose) into grape juice (must) into ethanol. Yeast is normally already present on grape skins. Fermentation can be done with this endogenous "wild yeast", but this procedure gives unpredictable results, which depend upon the exact types of yeast species present. For this reason, a pure yeast culture is usually added to the must; this yeast quickly dominates the fermentation. The wild yeasts are repressed, which ensures a reliable and predictable fermentation.

Most added wine yeasts are strains of S. cerevisiae, though not all strains of the species are suitable. Different S. cerevisiae yeast strains have differing physiological and fermentative properties, therefore the actual strain of yeast selected can have a direct impact on the finished wine. Significant research has been undertaken into the development of novel wine yeast strains that produce atypical flavour profiles or increased complexity in wines.

The growth of some yeasts, such as Zygosaccharomyces and Brettanomyces, in wine can result in wine faults and subsequent spoilage. Brettanomyces produces an array of metabolites when growing in wine, some of which are volatile phenolic compounds. Together, these compounds are often referred to as "Brettanomyces character", and are often described as "antiseptic" or "barnyard" type aromas. Brettanomyces is a significant contributor to wine faults within the wine industry.

Researchers from the University of British Columbia, Canada, have found a new strain of yeast that has reduced amines. The amines in red wine and Chardonnay produce off-flavors and cause headaches and hypertension in some people. About 30% of people are sensitive to biogenic amines, such as histamines.

Baking

Yeast, the most common one being S. cerevisiae, is used in baking as a leavening agent, where it converts the food/fermentable sugars present in dough into the gas carbon dioxide. This causes the dough to expand or rise as gas forms pockets or bubbles. When the dough is baked, the yeast dies and the air pockets "set", giving the baked product a soft and spongy texture. The use of potatoes, water from potato boiling, eggs, or sugar in a bread dough accelerates the growth of yeasts. Most yeasts used in baking are of the same species common in alcoholic fermentation. In addition, Saccharomyces exiguus (also known as S. minor), a wild yeast found on plants, fruits, and grains, is occasionally used for baking. In breadmaking, the yeast initially respires aerobically, producing carbon dioxide and water. When the oxygen is depleted, fermentation begins, producing ethanol as a waste product; however, this evaporates during baking.

A block of compressed fresh yeast

 

It is not known when yeast was first used to bake bread. The first records that show this use came from Ancient Egypt. Researchers speculate a mixture of flour meal and water was left longer than usual on a warm day and the yeasts that occur in natural contaminants of the flour caused it to ferment before baking. The resulting bread would have been lighter and tastier than the normal flat, hard cake. 

Active dried yeast, a granulated form in which yeast is commercially sold

 

Today, there are several retailers of baker's yeast; one of the earlier developments in North America is Fleischmann's Yeast, in 1868. During World War II, Fleischmann's developed a granulated active dry yeast which did not require refrigeration, had a longer shelf life than fresh yeast, and rose twice as fast. Baker's yeast is also sold as a fresh yeast compressed into a square "cake". This form perishes quickly, so must be used soon after production. A weak solution of water and sugar can be used to determine whether yeast is expired. In the solution, active yeast will foam and bubble as it ferments the sugar into ethanol and carbon dioxide. Some recipes refer to this as proofing the yeast, as it "proves" (tests) the viability of the yeast before the other ingredients are added. When a sourdough starter is used, flour and water are added instead of sugar; this is referred to as proofing the sponge.

When yeast is used for making bread, it is mixed with flour, salt, and warm water or milk. The dough is kneaded until it is smooth, and then left to rise, sometimes until it has doubled in size. The dough is then shaped into loaves. Some bread doughs are knocked back after one rising and left to rise again (this is called dough proofing) and then baked. A longer rising time gives a better flavour, but the yeast can fail to raise the bread in the final stages if it is left for too long initially.

Bioremediation

Some yeasts can find potential application in the field of bioremediation. One such yeast, Yarrowia lipolytica, is known to degrade palm oil mill effluent, TNT (an explosive material), and other hydrocarbons, such as alkanes, fatty acids, fats and oils. It can also tolerate high concentrations of salt and heavy metals, and is being investigated for its potential as a heavy metal biosorbent. Saccharomyces cerevisiae has potential to bioremediate toxic pollutants like arsenic from industrial effluent. Bronze statues are known to be degraded by certain species of yeast. Different yeasts from Brazilian gold mines bioaccumulate free and complexed silver ions.

Industrial ethanol production

The ability of yeast to convert sugar into ethanol has been harnessed by the biotechnology industry to produce ethanol fuel. The process starts by milling a feedstock, such as sugar cane, field corn, or other cereal grains, and then adding dilute sulfuric acid, or fungal alpha amylase enzymes, to break down the starches into complex sugars. A glucoamylase is then added to break the complex sugars down into simple sugars. After this, yeasts are added to convert the simple sugars to ethanol, which is then distilled off to obtain ethanol up to 96% in purity.

Saccharomyces yeasts have been genetically engineered to ferment xylose, one of the major fermentable sugars present in cellulosic biomasses, such as agriculture residues, paper wastes, and wood chips. Such a development means ethanol can be efficiently produced from more inexpensive feedstocks, making cellulosic ethanol fuel a more competitively priced alternative to gasoline fuels.

Nonalcoholic beverages

A kombucha culture fermenting in a jar

 

Yeast and bacteria in kombucha at 400×

 

A number of sweet carbonated beverages can be produced by the same methods as beer, except the fermentation is stopped sooner, producing carbon dioxide, but only trace amounts of alcohol, leaving a significant amount of residual sugar in the drink.

• Root beer, originally made by Native Americans, commercialized in the United States by Charles Elmer Hires and especially popular during Prohibition
• Kvass, a fermented drink made from rye, popular in Eastern Europe. It has a recognizable, but low alcoholic content.
• Kombucha, a fermented sweetened tea. Yeast in symbiosis with acetic acid bacteria is used in its preparation. Species of yeasts found in the tea can vary, and may include: Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii. Also popular in Eastern Europe and some former Soviet republics under the name chajnyj grib (Russian: Чайный гриб), which means "tea mushroom".
• Kefir and kumis are made by fermenting milk with yeast and bacteria.
• Mauby (Spanish: mabí), made by fermenting sugar with the wild yeasts naturally present on the bark of the Colubrina elliptica tree, popular in the Caribbean

Nutritional supplements

Yeast is used in nutritional supplements, especially those marketed to vegans. It is often referred to as "nutritional yeast" when sold as a dietary supplement. Nutritional yeast is a deactivated yeast, usually S.  cerevisiae. It is naturally low in fat and sodium as well as an excellent source of protein and vitamins, especially most B-complex vitamins (contrary to some claims, it contains little or no vitamin B₁₂), as well as other minerals and cofactors required for growth. Some brands of nutritional yeast, though not all, are fortified with vitamin B₁₂, which is produced separately by bacteria.

In 1920, the Fleischmann Yeast Company began to promote yeast cakes in a "Yeast for Health" campaign. They initially emphasized yeast as a source of vitamins, good for skin and digestion. Their later advertising claimed a much broader range of health benefits, and was censured as misleading by the Federal Trade Commission. The fad for yeast cakes lasted until the late 1930s.

Nutritional yeast has a nutty, cheesy flavor and is often used as an ingredient in cheese substitutes. Another popular use is as a topping for popcorn. It can also be used in mashed and fried potatoes, as well as in scrambled eggs. It comes in the form of flakes, or as a yellow powder similar in texture to cornmeal. In Australia, it is sometimes sold as "savoury yeast flakes". Though "nutritional yeast" usually refers to commercial products, inadequately fed prisoners have used "home-grown" yeast to prevent vitamin deficiency.

Probiotics

Some probiotic supplements use the yeast S. boulardii to maintain and restore the natural flora in the gastrointestinal tract. S. boulardii has been shown to reduce the symptoms of acute diarrhea, reduce the chance of infection by Clostridium difficile (often identified simply as C. difficile or C. diff), reduce bowel movements in diarrhea-predominant IBS patients, and reduce the incidence of antibiotic-, traveler's-, and HIV/AIDS-associated diarrheas.

Aquarium hobby

Yeast is often used by aquarium hobbyists to generate carbon dioxide (CO₂) to nourish plants in planted aquaria. CO₂ levels from yeast are more difficult to regulate than those from pressurized CO₂ systems. However, the low cost of yeast makes it a widely used alternative.

Yeast extract

Marmite and Vegemite, products made from yeast extract

 

Marmite and Vegemite are dark in colour

 

Yeast extract is the common name for various forms of processed yeast products that are used as food additives or flavours. They are often used in the same way that monosodium glutamate (MSG) is used and, like MSG, often contain free glutamic acid. The general method for making yeast extract for food products such as Vegemite and Marmite on a commercial scale is to add salt to a suspension of yeast, making the solution hypertonic, which leads to the cells' shrivelling up. This triggers autolysis, wherein the yeast's digestive enzymes break their own proteins down into simpler compounds, a process of self-destruction. The dying yeast cells are then heated to complete their breakdown, after which the husks (yeast with thick cell walls that would give poor texture) are separated. Yeast autolysates are used in Vegemite and Promite (Australia); Marmite (the United Kingdom); the unrelated Marmite (New Zealand); Vitam-R (Germany); and Cenovis (Switzerland).

Scientific research

Diagram showing a yeast cell

 

Several yeasts, in particular S. cerevisiae and S. pombe, have been widely used in genetics and cell biology, largely because they are simple eukaryotic cells, serving as a model for all eukaryotes, including humans, for the study of fundamental cellular processes such as the cell cycle, DNA replication, recombination, cell division, and metabolism. Also, yeasts are easily manipulated and cultured in the laboratory, which has allowed for the development of powerful standard techniques, such as yeast two-hybrid, synthetic genetic array analysis, and tetrad analysis. Many proteins important in human biology were first discovered by studying their homologues in yeast; these proteins include cell cycle proteins, signaling proteins, and protein-processing enzymes.

On 24 April 1996, S. cerevisiae was announced to be the first eukaryote to have its genome, consisting of 12 million base pairs, fully sequenced as part of the Genome Project. At the time, it was the most complex organism to have its full genome sequenced, and the work seven years and the involvement of more than 100 laboratories to accomplish. The second yeast species to have its genome sequenced was Schizosaccharomyces pombe, which was completed in 2002. It was the sixth eukaryotic genome sequenced and consists of 13.8 million base pairs. As of 2014, over 50 yeast species have had their genomes sequenced and published.

Genomic and functional gene annotation of the two major yeast models can be accessed via their respective model organism databases: SGD and PomBase.

Genetically engineered biofactories

Various yeast species have been genetically engineered to efficiently produce various drugs, a technique called metabolic engineering. S. cerevisiae is easy to genetically engineer; its physiology, metabolism and genetics are well known, and it is amenable for use in harsh industrial conditions. A wide variety of chemical in different classes can be produced by engineered yeast, including phenolics, isoprenoids, alkaloids, and polyketides. About 20% of biopharmaceuticals are produced in S. cerevisiae, including insulin, vaccines for hepatitis, and human serum albumin.

Pathogenic yeasts

A photomicrograph of Candida albicans showing hyphal outgrowth and other morphological characteristics

 

Some species of yeast are opportunistic pathogens that can cause infection in people with compromised immune systems. Cryptococcus neoformans and Cryptococcus gattii are significant pathogens of immunocompromised people. They are the species primarily responsible for cryptococcosis, a fungal disease that occurs in about one million HIV/AIDS patients, causing over 600,000 deaths annually. The cells of these yeast are surrounded by a rigid polysaccharide capsule, which helps to prevent them from being recognised and engulfed by white blood cells in the human body.

Yeasts of the genus Candida, another group of opportunistic pathogens, cause oral and vaginal infections in humans, known as candidiasis. Candida is commonly found as a commensal yeast in the mucous membranes of humans and other warm-blooded animals. However, sometimes these same strains can become pathogenic. The yeast cells sprout a hyphal outgrowth, which locally penetrates the mucosal membrane, causing irritation and shedding of the tissues. The pathogenic yeasts of candidiasis in probable descending order of virulence for humans are: C. albicans, C. tropicalis, C. stellatoidea, C. glabrata, C. krusei, C. parapsilosis, C. guilliermondii, C. viswanathii, C. lusitaniae, and Rhodotorula mucilaginosa. Candida glabrata is the second most common Candida pathogen after C. albicans, causing infections of the urogenital tract, and of the bloodstream (candidemia).

Food spoilage

Yeasts are able to grow in foods with a low pH (5.0 or lower) and in the presence of sugars, organic acids, and other easily metabolized carbon sources. During their growth, yeasts metabolize some food components and produce metabolic end products. This causes the physical, chemical, and sensible properties of a food to change, and the food is spoiled. The growth of yeast within food products is often seen on their surfaces, as in cheeses or meats, or by the fermentation of sugars in beverages, such as juices, and semiliquid products, such as syrups and jams. The yeast of the genus Zygosaccharomyces have had a long history as spoilage yeasts within the food industry. This is mainly because these species can grow in the presence of high sucrose, ethanol, acetic acid, sorbic acid, benzoic acid, and sulphur dioxide concentrations, representing some of the commonly used food preservation methods. Methylene blue is used to test for the presence of live yeast cells. In oenology, the major spoilage yeast is Brettanomyces bruxellensis. 

Candida blankii has been detected in Iberian ham and meat.

Symbiosis

An Indian study of seven bee species and 9 plant species found 45 yeast species from 16 genera colonise the nectaries of flowers and honey stomachs of bees. Most were members of the genus Candida; the most common species in honey bee stomachs was Dekkera intermedia, while the most common species colonising flower nectaries was Candida blankii. Although the mechanics are not fully understood, it was found that A. indica flowers more if C. blankii are present.

Carnegie Corporation of New York

From Wikipedia, the free encyclopedia

Carnegie Corporation of New York

The Corporation's headquarters at 437 Madison Avenue in New York
Formation	9 June 1911; 107 years ago
Founder	Andrew Carnegie
Type	Foundation
Legal status	Nonprofit organization
Purpose	To promote the advancement and diffusion of knowledge and understanding
Headquarters	New York, United States
Region	Global
Methods	Grant-giving
Fields	Education, democracy, international peace, higher education in Africa
President	Vartan Gregorian
Chair of the Board	Thomas Kean
Revenue (2018)	$253 million
Expenses (2018)	$180 million
Endowment (2018)	$3.5 billion
Website	www.carnegie.org

The Carnegie Corporation of New York MHL is a philanthropic fund established by Andrew Carnegie in 1911 to support education programs across the United States, and later the world. Carnegie Corporation has endowed or otherwise helped to establish institutions that include the United States National Research Council, what was then the Russian Research Center at Harvard University (now known as the Davis Center for Russian and Eurasian Studies), the Carnegie libraries and the Children's Television Workshop. It also for many years generously funded Carnegie's other philanthropic organizations, the Carnegie Endowment for International Peace (CEIP), the Carnegie Foundation for the Advancement of Teaching (CFAT), and the Carnegie Institution for Science (CIS).

History

Founding and early years

By 1911 Andrew Carnegie had endowed five organizations in the US and three in the United Kingdom, and given more than $43 million to build public libraries and given another almost $110 million elsewhere. But ten years after he sold the Carnegie Steel Company, more than $150 million remained in his accounts and at 76, he wearied of philanthropic choices. Long-time friend Elihu Root suggested he establish a trust. Carnegie transferred most of his remaining fortune into it, and made the trust responsible for distributing his wealth after he died. Carnegie's previous charitable giving had used conventional organizational structures, but he chose a corporation as the structure for his last and largest trust. Chartered by the State of New York as the Carnegie Corporation of New York, the corporation's capital fund, originally worth about $135 million, had a market value of $1.55 billion on March 31, 1999.

In 1911-1912, Carnegie gave the corporation $125 million. At that time the corporation was the largest single philanthropic charitable trust ever established. He also made it a residual legatee under his will so it therefore received an additional $10 million, the remainder of his estate after had paid his other bequests. Carnegie reserved a portion of the corporation's assets for philanthropy in Canada and the then-British Colonies, an allocation first referred to as the Special Fund, then the British Dominions and Colonies Fund, and later the Commonwealth Program. Charter amendments have allowed the corporation to use 7.4 percent of its income in countries that are or once were members of the British Commonwealth.

In its early years Carnegie served as both president and trustee. His private secretary James Bertram and his financial agent, Robert A. Franks, acted as trustees as well and, respectively, corporation secretary and treasurer. This first executive committee made most of the funding decisions. Other seats on the board were held ex officio by presidents of five previously-established US Carnegie organizations:

• Carnegie Institute (of Pittsburgh) (1896),
• Carnegie Institution of Washington (1902),
• Carnegie Hero Fund Commission (1904),
• Carnegie Foundation for the Advancement of Teaching (CFAT) (1905),
• Carnegie Endowment for International Peace (CEIP) (1910).

After Carnegie died in 1919, the trustees elected a full-time salaried president as the trust's chief executive officer and ex officio trustee. For a time the corporation's gifts followed the patterns Carnegie had already established. Grants for public libraries and church organs continued until 1917, and also went to other Carnegie organizations, and universities, colleges, schools, and educational agencies. Carnegie's letter of gift to the original trustees making the endowment said that the trustees would "best conform to my wishes by using their own judgement. "Corporation strategies changed over the years but remained focused on education, although the trust did also increasingly fund scientific research, convinced that the nation needed more scientific expertise and "scientific management". It also worked to build research facilities for the natural and social sciences. The corporation made large grants to the National Academy of Sciences/National Research Council, the Carnegie Institution of Washington, the National Bureau of Economic Research, Stanford University's now-defunct Food Research Institute and the Brookings Institution, then became interested in adult education and lifelong learning, an obvious follow-on to Carnegie's vision for libraries as "the university of the people". In 1919 it initiated the Americanization Study to explore educational opportunities for adults, primarily for new immigrants.

Frederick P. Keppel

With Frederick P. Keppel as president (1923-1941), the Carnegie Corporation shifted from creating public libraries to strengthening library infrastructure and services, developing adult education, and adding arts education to the programs of colleges and universities. The foundation's grants in this period have a certain eclectic quality and remarkable perseverance in its chosen causes.

Keppel initiated a famous 1944 study of race relations in the United States by the Swedish social economist Gunnar Myrdal in 1937 by naming a non-American outsider as manager of the study. His theory that this task should be done by someone unencumbered by traditional attitudes or earlier conclusions led to Myrdal's widely heralded book American Dilemma (1944). The book had no immediate effect on public policy, but was later much cited in legal challenges to segregation. Keppel believed foundations should make facts available and let them facts speak for themselves. His cogent writings on philanthropy made a lasting impression on field and influenced the organization and leadership of many new foundations.

In 1927 Keppel toured sub-Saharan Africa and recommended a first set of grants to establish public schools in eastern and southern Africa. Other grants went to for municipal library development in South Africa. During 1928 the corporation initiated the Carnegie Commission on the Poor White Problem in South Africa. Better known as the "Carnegie Poor White Study", it promoted strategies to improve the lives of rural Afrikaner whites and other poor whites in general. A memorandum sent to Keppel said there was "little doubt that if the natives were given full economic opportunity, the more competent among them would soon outstrip the less competent whites" Keppel endorsed the project that produced the report, motivated by his concern with maintaining existing racial boundaries.{{unclear if this means he wants to keep them and that is why he is concerned, or he is concerned that they exist and sees their existence as the problem. The corporation's concern for the so-called "poor white problem" in South Africa stemmed at least in part from similar misgivings about poor whites in the American South.

White poverty contradicted notions of racial superiority and hence it became the emphasis of "scientific" study. The report recommended that "employment sanctuaries" be established for poor white workers and that poor white workers should replace "native" black workers in most skilled aspects of the economy. The authors of the report suggested that racial deterioration and miscegenation would be the outcome unless something was done to help poor whites, and endorsed the idea that maintaining white superiority would require help from social institutions. The report expressed fear of a loss of white racial pride, and that poor whites would not be able to resist "Africanisation." Seeking to prevent a class-based movement uniting the poor of all races, the report advised increasing race as opposed to class differences in order to make race the social criterion of status, not class.

Charles Dollard

World War II and its immediate aftermath were a relatively inactive period for the Carnegie Corporation. Charles Dollard had joined the staff in 1939 as Keppel's assistant and became president in 1948. The foundation took greater interest in the social sciences, and particularly the study of human behavior. The trust also entered into international affairs. Dollard urged it to fund quantitative, "objective" social science research like research in physical sciences, and help to diffuse the results through major universities. The corporation advocated for standardized testing in schools to determine academic merit regardless of the student's socio-economic background. Its initiatives have also included helping to broker the creation of the Educational Testing Service in 1947.

The corporation determined that the US increasingly needed policy and scholarly expertise in international affairs, and so tied into area studies programs at colleges and universities as well as the Ford Foundation. In 1948 the trust also provided the seed money to establish the Russian Research Center at Harvard University, today known as the Davis Center for Russia and Eurasian Studies, as an organization that could address large-scale research from both a policy and educational points of view.

In 1951 the Group Areas Act took effect in South Africa and effectively put the apartheid system into place, leading to political ascendancy for Afrikaners and dispossession for many Africans and colored people suddenly required to live in certain areas of the country only, on pain of imprisonment for remaining in possession of homes in areas designated for whites. The Carnegie corporation pulled its philanthropic endeavors from South Africa for more than two decades after this political change, turning its attention from South Africa to developing East African and West African universities instead.

John Gardner

John W. Gardner was promoted from a staff position to the presidency in 1955. Gardner simultaneously became president of the CFAT, which was housed at the corporation. During Gardner's time in office the Carnegie Corporation worked to upgrade academic competence in foreign area studies and strengthened its liberal arts education program. In the early 1960s it inaugurated a continuing education program and funded development of new models for advanced and professional study by mature women. Gardner's interest in leadership development led to the White House Fellows program in 1964. 

Notable grant projects in higher education in sub-Saharan Africa include the 1959-60 Ashby Commission study of Nigerian needs in postsecondary education. This study stimulated aid increases from the United Kingdom, Europe, and the United States to African nations' systems of higher and professional education. Gardner had a strong interest in education, but as a psychologist he believed in the behavioral sciences and urged the corporation to funded much of the US' basic research on cognition, creativity, and the learning process, particularly among young children, associating psychology and education. Perhaps its most important contribution to reform of pre-college education at this time was the series of education studies done by James B. Conant, former president of Harvard University; in particular, Conant's study of comprehensive American high schools (1959) resolved public controversy concerning the purpose of public secondary education, and made the case that schools could adequately educate both average students and the academically gifted.

Under Gardner, the corporation embraced strategic philanthropy—planned, organized, and deliberately constructed to attain stated ends. Funding criteria no longer required just a socially desirable project. The corporation sought out projects that would produce knowledge leading to useful results, communicated to decision-makers, the public, and the media, in order to foster policy debate. Developing programs that larger organizations, especially governments, could implement and scale in size became a major objective. The policy shift to institutional knowledge transfer came in part as a response to relatively diminished resources that made it necessary to leverage assets and "multiplier effects" to have any effect at all. The corporation considered itself a trendsetter in philanthropy, often funding research or providing seed money for ideas while others financed more costly operations. For example, ideas it advanced resulted in the National Assessment of Educational Progress, later adopted by the federal government. A foundation's most precious asset was its sense of direction, Gardner said, gathering a competent professional staff of generalists that he called his "cabinet of strategy," and regarded as a resource as important to the corporation as its endowment.

Alan Pifer

While Gardner's opinion of educational equality was to multiply the channels through which an individual could pursue opportunity, it was during the term of long-time staff member Alan Pifer, who became acting president during 1965 and president during 1967 (again of both Carnegie Corporation and the CFAT), that the foundation began to respond to claims by various groups, including women, for increased power and wealth. The corporation developed three interlocking objectives: prevention of educational disadvantage; equality of educational opportunity in the schools; and broadened opportunities in higher education. A fourth objective cutting across these programs was to improve the democratic performance of government. Grants were made to reform state government as the laboratories of democracy, underwrite voter education drives, and mobilize youth to vote, among other measures. Use of the legal system became a method for achieving equal opportunity in education, as well as redress of grievance, and the corporation joined the Ford and Rockefeller foundations and others in funding educational litigation by civil rights organizations. It also initiated a multifaceted program to train black lawyers in the South for the practice of public interest law and to increase the legal representation of black people.

Maintaining its commitment to early childhood education, the corporation endorsed the application of research knowledge in experimental and demonstration programs, which subsequently provided strong evidence of the long-term positive effects of high-quality early education, particularly for the disadvantaged. A 1980 report on an influential study, the Perry Preschool Project of the HighScope Educational Research Foundation, on the outcomes for sixteen-year-olds enrolled in the experimental preschool programs provided crucial evidence that safeguarded Project Head Start in a time of deep cuts to federal social programs. The foundation also promoted educational children's television and initiated the Children's Television Workshop, producer of Sesame Street and other noted children's programs. Growing belief in the power of educational television prompted creation of the Carnegie Commission on Educational Televisio n, whose recommendations were adopted into the Public Broadcasting Act of 1968 that established a public broadcasting system. Many other reports on US education the corporation financed at this time, included Charles E. Silberman's acclaimed Crisis in the Classroom (1971), and the controversial Inequality: A Reassessment of the Effect of Family and Schooling in America by Christopher Jencks (1973). This report confirmed quantitative research, e.g. the Coleman Report, showed that in public schools resources only weakly correlated with educational outcomes, which coincided with the foundation's burgeoning interest in improved school effectiveness.

Becoming involved with South Africa again during the mid-1970s, the corporation worked through universities to increase the legal representation of black people and increase the practice of public interest law. At the University of Cape Town, it established the Second Carnegie Inquiry into Poverty and Development in Southern Africa, this time to examine the legacies of apartheid and make recommendations to nongovernmental organizations for actions commensurate with the long-run goal of achieving a democratic, interracial society.

The influx of nontraditional students and "baby boomers" into higher education prompted formation of the Carnegie Commission on Higher Education (1967), funded by the CFAT. (During 1972, the CFAT became an independent institution after experiencing three decades of restricted control over its own affairs.) In its more than ninety reports, the commission made detailed suggestions for introducing more flexibility into the structure and financing of higher education. One outgrowth of the commission's work was creation of the federal Pell grants program offering tuition assistance for needy college students. The corporation promoted the Doctor of Arts "teaching" degree as well as various off-campus undergraduate degree programs, including the Regents Degree of the State of New York and Empire State College. The foundation's combined interest in testing and higher education resulted in establishment of a national system of college credit by examination (College-Level Entrance Examination Program of the College Entrance Examination Board). Building on its past programs to promote the continuing education of women, the foundation made a series of grants for the advancement of women in academic life. Two other study groups formed to examine critical problems in American life were the Carnegie Council on Children (1972) and the Carnegie Commission on the Future of Public Broadcasting (1977), the latter formed almost ten years after the first commission.

David A. Hamburg

David A. Hamburg, a physician, educator, and scientist with a public health background, became president in 1982 intending to mobilize the best scientific and scholarly talent and thinking on "prevention of rotten outcomes" - from early childhood to international relations. The corporation pivoted from higher education to the education and healthy development of children and adolescents, and the preparation of youth for a scientific and technological, knowledge-driven world. In 1984 the corporation established the Carnegie Commission on Education and the Economy. Its major publication, A Nation Prepared (1986), reaffirmed the role of the teacher as the "best hope" for quality in elementary and secondary education. That report led to the establishment a year later of the National Board for Professional Teaching Standards, to consider ways to attract able candidates to teaching and recognize and retain them. At the corporation's initiative, the American Association for the Advancement of Science issued two reports, Science for All Americans (1989) and Benchmarks for Science Literacy (1993), which recommended a common core of learning in science, mathematics, and technology for all citizens and helped set national standards of achievement.

A new emphasis for the corporation was the danger to world peace posed by the superpower confrontation and weapons of mass destruction. The foundation underwrote scientific study of the feasibility of the proposed federal Strategic Defense Initiative and joined the John D. and Catherine T. MacArthur Foundation to support the analytic work of a new generation of arms control and nuclear nonproliferation experts. After the end of the USSR, corporation grants helped promote the concept of cooperative security among erstwhile adversaries and projects to build democratic institutions in the former Soviet Union and Central Europe. The Prevention of Proliferation Task Force, coordinated by a grant to the Brookings Institution, inspired the Nunn-Lugar Amendment to the Soviet Threat Reduction Act of 1991, intended to help dismantle Soviet nuclear weapons and reduce proliferation risks. More recently, the corporation addressed interethnic and regional conflict and funded projects seeking to diminish the risks of a wider war resulting from civil strife. Two Carnegie commissions, Reducing the Nuclear Danger (1990), the other Preventing Deadly Conflict (1994), addressed the dangers of human conflict and the use of weapons of mass destruction. The corporation's emphasis in Commonwealth Africa, meanwhile, shifted to women's health and political development and the application of science and technology, including new information systems, to foster research and expertise in indigenous scientific institutions and universities. 

During Hamburg's tenure, dissemination achieved even greater primacy with respect to strategic philanthropy. Consolidation and diffusion of the best available knowledge from social science and education research was used to improve social policy and practice, as partner with major institutions with the capability to influence public thought and action. If "change agent" was a major term during Pifer's time, "linkage" became a byword in Hamburg's. The corporation increasingly used its convening powers to bring together experts across disciplinary and sectoral boundaries to create policy consensus and promote collaboration. 

Continuing tradition, the foundation established several other major study groups, often directed by the president and managed by a special staff. Three groups covered the educational and developmental needs of children and youth from birth to age fifteen: the Carnegie Council on Adolescent Development (1986), the Carnegie Task Force on Meeting the Needs of Young Children (1991), and the Carnegie Task Force on Learning in the Primary Grades (1994). Another, the Carnegie Commission on Science, Technology, and Government (1988), recommended ways that government at all levels could make more effective use of science and technology in their operations and policies. Jointly with the Rockefeller Foundation, the corporation financed the National Commission on Teaching & America's Future, whose report, What Matters Most (1996), provided a framework and agenda for teacher education reform across the country. These study groups drew on knowledge generated by grant programs and inspired follow-up grantmaking to implement their recommendations.

Vartan Gregorian

During the presidency of Vartan Gregorian the corporation reviewed its management structure and grants programs. In 1998 the corporation established four primary program headings: education, international peace and security, international development, and democracy. In these four main areas, the corporation continued to engage with major issues confronting higher education. Domestically, it emphasized reform of teacher education and examined the current status and future of liberal arts education in the United States. Abroad, the corporation sought to devise methods to strengthen higher education and public libraries in Commonwealth Africa. As a cross-program initiative, and in cooperation with other foundations and organizations, the corporation instituted a scholars program, offering funding to individual scholars, particularly in the social sciences and humanities, in the independent states of the former Soviet Union.

Honours

• Honorary-Member of the Order of Liberty, Portugal (5 April 2018)

Medicinal fungi

From Wikipedia, the free encyclopedia

Medicinal fungi are those fungi which produce medically significant metabolites or can be induced to produce such metabolites using biotechnology. The range of medically active compounds that have been identified include antibiotics, anti-cancer drugs, cholesterol inhibitors, psychotropic drugs, immunosuppressants and even fungicides. Although initial discoveries centred on simple moulds of the type that cause spoilage of food, later work identified useful compounds across a wide range of fungi.

History

Although fungi products have been used in traditional and folk medicines, probably since pre-history, the ability to identify beneficial properties and then extract the active ingredient started with the discovery of penicillin by Alexander Fleming in 1928. Since that time, many additional antibiotics have been discovered and the potential for fungi to synthesize biologically active molecules, useful in a wide range of clinical therapies, has been extensively exploited.

Pharmacological research has now isolated antifungal, antiviral, and antiprotozoan, isolates from fungi.

The fungus with probably the longest record of medicinal use, Ganoderma lucidum, is known in Chinese as líng zhī ("spirit plant"), and in Japanese as mannentake ("10,000-year mushroom"). In ancient Japan, Grifola frondosa was worth its weight in silver, although no significant therapeutic benefits have been demonstrated in humans.

Studies have shown another species of genus Ganoderma, G. applanatum, contains compounds with anti-tumor and anti-fibrotic properties. 

Inonotus obliquus was used in Russia as early as the 16th century, and it featured in Alexandr Solzhenitsyn's 1967 novel Cancer Ward.

Applications

Cancer

40x brightfield microscopy of Pestalotia/Pestalotiopsis spores. Note the appendages. Some strains (Pestalotiopsis pauciseta) produce taxol.

 

Paclitaxel is synthesised using Penicillium raistrickii and plant cell fermentation. Fungi can synthesize other mitotic inhibitors including vinblastine, vincristine, podophyllotoxin, griseofulvin, aurantiamine, oxaline, and neoxaline.

11,11'-Dideoxyverticillin A, an isolate of marine Penicillium, was used to create dozens of semi-synthetic anticancer compounds. 11,11'-Dideoxyverticillin A, andrastin A, barceloneic acid A, and barceloneic acid B, are farnesyl transferase inhibitors that can be made by Penicillium. 3-O-Methylfunicone, anicequol, duclauxin, and rubratoxin B, are anticancer/cytotoxic metabolites of Penicillium. 

Penicillium is a potential source of the leukemia medicine asparaginase.

Some countries have approved Beta-glucan fungal extracts lentinan, polysaccharide-K, and polysaccharide peptide as immunologic adjuvants. Evidence suggests this use as effective in prolonging and improving the quality of life for patients with certain cancers, although the Memorial Sloan-Kettering Cancer Center observes that "well designed, large scale studies are needed to establish the role of lentinan as a useful adjunct to cancer treatment". According to Cancer Research UK, "there is currently no evidence that any type of mushroom or mushroom extract can prevent or cure cancer". Fungal metabolites such as ergosterol, clavilactones, and triterpenoids are efficient Cdk inhibitors that lead to G1/S or G2/M arrest of cancer cells. Other metabolites, such as panepoxydone, are inhibitors of NF-κB. Fucose and mannose fragments of fungal cell wall are antagonists of VEGF-receptors 

Antibacterial agents (antibiotics)

Alexander Fleming led the way to the beta-lactam antibiotics with the Penicillium mold and penicillin. Subsequent discoveries included alamethicin, aphidicolin, brefeldin A, Cephalosporin, cerulenin, citromycin, eupenifeldin, fumagillin, fusafungine, fusidic acid, itaconic acid, MT81, nigrosporin B, usnic acid, verrucarin A, vermiculine and many others. 

Ling Zhi-8, an immunomodulatory protein isolated from Ganoderma lucidum

 

Antibiotics retapamulin, tiamulin, and valnemulin are derivatives of the fungal metabolite pleuromutilin. Plectasin, austrocortilutein, austrocortirubin, coprinol, oudemansin A, strobilurin, illudin, pterulone, and sparassol are antibiotics isolated from basidiomycete species.

Cholesterol biosynthesis inhibitors

The red yeast rice fungus, Monascus purpureus, can synthesize three statins.

 

Statins are an important class of cholesterol-lowering drugs; the first generation of statins were derived from fungi. Lovastatin, the first commercial statin, was extracted from a fermentation broth of Aspergillus terreus. Industrial production is now capable of producing 70 mg lovastatin per kilogram of substrate. The red yeast rice fungus, Monascus purpureus, can synthesize lovastatin, mevastatin, and the simvastatin precursor monacolin J. Nicotinamide riboside, a cholesterol biosynthesis inhibitor, is made by Saccharomyces cerevisiae.

Antifungals

Some antifungals are derived or extracted from other fungal species. Griseofulvin is derived from a number of Penicillium species, caspofungin is derived from Glarea lozoyensis. Strobilurin, azoxystrobin, micafungin, and echinocandins, are all extracted from fungi. Anidulafungin is a derivative of an Aspergillus metabolite.

Immunosuppressants

Ciclosporin, was discovered in Tolypocladium inflatum. Bredinin was discovered in Eupenicillium brefeldianum. Mycophenolic acid was discovered in Penicillium stoloniferum. Thermophilic fungi were the source of the fingolimod precursor myriocin. Aspergillus synthesizes immunosuppressants gliotoxin and endocrocin. Subglutinols are immunosuppressants isolated from Fusarium subglutinans. Other compounds include mizoribine.

Malaria

Codinaeopsin, efrapeptins, zervamicins, and antiamoebin, are made by fungi.

Diabetes

Many fungal isolates act as DPP-4 inhibitors, alpha-glucosidase inhibitors, and alpha amylase inhibitors in vitro. Ternatin is a fungal isolate that suppresses hyperglycemia. Aspergillusol A is an alpha-glucosidase inhibitor made by Aspergillus. Sclerotiorin is an aldose reductase inhibitor made by Penicillium.

Psychotropic effects

A number of fungi have well documented psychotropic effects, some of them severe and associated with sometimes acute and life-threatening side-effects. Well known amongst these is Amanita muscaria, the fly agaric. More widely used informally are a range of fungi collectively known as "magic mushrooms", which contain psilocybin and psilocin. 

The history of bread-making is also peppered with references to deadly ergotism caused by ergot, most commonly Claviceps purpurea, a parasite of cereal crops. A number of therapeutically useful drugs have subsequently been extracted from ergot including ergotamine, pergolide and cabergoline.

Psychotropic compounds created from ergot alkaloids also include dihydroergotamine, methysergide, methylergometrine, hydergine, nicergoline, lisuride, bromocriptine, cabergoline, pergolide. Polyozellus multiplex synthesizes prolyl endopeptidase inhibitors polyozellin, thelephoric acid, kynapcins. Neurotrophic fungal isolates include L-theanine, tricholomalides, scabronines, termitomycesphins. Many fungi synthesize the partial, non-selective, serotonin receptor agonist/analog psilocin.

A number of other fungal species, including species of Aspergillus and Penicillium, have been induced to produce ergot alkaloids.

Vitamins

The photochemistry of vitamin D biosynthesis

 

Fungi are a source of ergosterol which can be converted to vitamin D upon exposure to ultraviolet light to synthesize vitamins D₂ (ergocalciferol), D₄ (22-dihydroergocalciferol), and D₁ (Lumisterol+D₂).

Phytase

Aspergillus niger is used to produce recombinant phytase, an enzyme added to animal feeds to improve absorption of phosphorus.

Edible species containing drugs

Edible species which contain drugs (biologically active constituents) include:

• Agaricus subrufescens (Agaricus blazei/brasiliensis, almond mushroom) is a fungus associated with Brazil and Japan. Blazein, a bioactive steroid, was isolated from A. subrufescens.
• The adenosine analog cordycepin was originally isolated from Cordyceps. Other Cordyceps isolates include, cordymin, cordycepsidone, and cordyheptapeptide. CS-4 is commercially sold as C. sinensis, but Cs-4 has recently been confirmed to be a different species from the Cordyceps species used in traditional Chinese medicine. CS-4 is properly known as Paecilomyces hepiali. Hirsutella sinensis is the accepted asexual form of C. sinensis.
• Ganoderma lucidum (Ling zhi, mannentake, reishi) contains p-hydroxybenzoic acid, cinnamic acid, and lanostane-type triterpenoids such as ganoderic acids.
• Hydnellum peckii has yielded atromentin, a compound isolated from the mycorrhiza, and subsequently its biosynthesis has been characterized.
• Lentinula edodes (Shiitake) has been used as a source of Lentinan, AHCC, and eritadenine.
• Schizophyllum commune (Split gill) has yielded schizophyllan (SPG, sizofiran, sonifilan). Hydrophobins were originally isolated from S. commune. A chemically analogous polysaccharide, scleroglucan, is an isolate of Sclerotium rolfsii.
• Tolypocladium inflatum Gams yields the immunosuppressant ciclosporin.
• Trametes versicolor (Coriolus versicolor, yun zhi, kawaratake, turkey tail) have produced protein-bound polysaccharides PSK and PSP (polysaccharopeptide) from different mycelia strains.
• Ustilago maydis (Mexican truffle, huitlacoche, corn fungus) synthesises ustilagine and ustilagic acid.

Yeasts

Saccharomyces is used industrially to produce the amino acid lysine, as well as recombinant proteinsinsulin and Hepatitis B surface antigen. Transgenic yeast are used to produce artemisinin, as well as a number of insulin analogs. Candida is used industrially to produce vitamins ascorbic acid and riboflavin. Pichia is used to produce the amino acid tryptophan and the vitamin pyridoxine. Rhodotorula is used to produce the amino acid phenylalanine. Moniliella is used industrially to produce the sugar alcoholerythritol.