Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute 1% of all described fungal species.
Basidiomycota is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: agarics, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and Cryptococcus, the human pathogenic yeast.
Sourdough or sourdough bread is a bread made by the fermentation of dough using wild lactobacillaceae and yeast. Lactic acid from fermentation imparts a sour taste and improves keeping qualities.
Saccharomyces cerevisiae is a species of yeast. The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes. It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology, much like Escherichia coli as the model bacterium. It is the microorganism behind the most common type of fermentation. S. cerevisiae cells are round to ovoid, 5–10 μm in diameter. It reproduces by budding.
Schizosaccharomyces pombe, also called "fission yeast", is a species of yeast used in traditional brewing and as a model organism in molecular and cell biology. It is a unicellular eukaryote, whose cells are rod-shaped. Cells typically measure 3 to 4 micrometres in diameter and 7 to 14 micrometres in length. Its genome, which is approximately 14.1 million base pairs, is estimated to contain 4,970 protein-coding genes and at least 450 non-coding RNAs.
Cryptococcus is a genus of fungi in the family Cryptococcaceae that includes both yeasts and filamentous species. The filamentous, sexual forms or teleomorphs were formerly classified in the genus Filobasidiella, while Cryptococcus was reserved for the yeasts. Most yeast species formerly referred to Cryptococcus have now been placed in different genera. The name Cryptococcus comes from the Greek for "hidden sphere". Some Cryptococcus species cause a disease called cryptococcosis.
Malassezia is a genus of fungi. It is the sole genus in family Malasseziaceae, which is the only family in order Malasseziales, itself the single member of class Malasseziomycetes. Malassezia species are naturally found on the skin surfaces of many animals, including humans. In occasional opportunistic infections, some species can cause hypopigmentation or hyperpigmentation on the trunk and other locations in humans. Allergy tests for these fungi are available.
Neolecta is a genus of ascomycetous fungi that have fruiting bodies in the shape of unbranched to lobed bright yellowish, orangish to pale yellow-green colored, club-shaped, smooth, fleshy columns up to about 7 cm tall. The species share the English designation "Earth tongues" along with some better-known fungi with a similar general form, but in fact they are only distantly related.
The Ustilaginales are an order of fungi within the class Ustilaginomycetes. The order contained 8 families, 49 genera, and 851 species in 2008.
Serine/threonine-protein kinases SGK represent a kinase subfamily with orthologs found across animal clades and in yeast. In most vertebrates, including humans, there are three isoforms encoded by the genes SGK1, SGK2, and SGK3. The name Serum/glucocorticoid-regulated kinase refers to the first cloning of a SGK family member from a cDNA library screen for genes upregulated by the glucocorticoid dexamethasone in a rat mammary epithelial tumor cell line. The first human family member was cloned in a screen of hepatocellular genes regulated in response to cellular hydration or swelling.
Kexin is a prohormone-processing protease, specifically a yeast serine peptidase, found in the budding yeast. It catalyzes the cleavage of -Lys-Arg- and -Arg-Arg- bonds to process yeast alpha-factor pheromone and killer toxin precursors. The human homolog is PCSK4. It is a family of subtilisin-like peptidases. Even though there are a few prokaryote kexin-like peptidases, all kexins are eukaryotes. The enzyme is encoded by the yeast gene KEX2, and usually referred to in the scientific community as Kex2p. It shares structural similarities with the bacterial protease subtilisin. The first mammalian homologue of this protein to be identified was furin. In the mammal, kexin-like peptidases function in creating and regulating many differing proproteins.
Pho4 is a protein with a basic helix-loop-helix (bHLH) transcription factor. It is found in S. cerevisiae and other yeasts. It functions as a transcription factor to regulate phosphate responsive genes located in yeast cells. The Pho4 protein homodimer is able to do this by binding to DNA sequences containing the bHLH binding site 5'-CACGTG-3'. This sequence is found in the promoters of genes up-regulated in response to phosphate availability such as the PHO5 gene.
The Agaricostilbomycetes are a class of fungi in the subdivision Pucciniomycotina of the Basidiomycota. The class consists of a single order, six families, and 15 genera. Most species are known only from their yeast states. Where known, basidiocarps (fruitbodies) are typically small and stilboid (pin-shaped).
The Microbotryomycetes are a class of fungi in the subdivision Pucciniomycotina of the Basidiomycota. The class currently contains eight orders, plus three additional, unassigned families, plus seven additional, unassigned genera. Many species are known only from their yeast states. Species with hyphal states typically produce auricularioid basidia and are often parasitic on other fungi or plants. Several species in the genera Rhodotorula and Sporobolomyces are opportunistic human pathogens.
An autophagosome is a spherical structure with double layer membranes. It is the key structure in macroautophagy, the intracellular degradation system for cytoplasmic contents. After formation, autophagosomes deliver cytoplasmic components to the lysosomes. The outer membrane of an autophagosome fuses with a lysosome to form an autolysosome. The lysosome's hydrolases degrade the autophagosome-delivered contents and its inner membrane.
The Sporidiobolales are an order of fungi in the subdivision Pucciniomycotina. The order contains a single family, the Sporidiobolaceae, which currently contains three genera. Most species are known only from their yeast states. Hyphal states produce teliospores from which auricularioid basidia emerge, bearing basidiospores. Species occur worldwide and have been isolated from a wide variety of substrates. Two species, Rhodotorula mucilaginosa and R. glutinis, have been known to cause disease in humans.
The role of yeast in winemaking is the most important element that distinguishes wine from fruit juice. In the absence of oxygen, yeast converts the sugars of the fruit into alcohol and carbon dioxide through the process of fermentation. The more sugars in the grapes, the higher the potential alcohol level of the wine if the yeast are allowed to carry out fermentation to dryness. Sometimes winemakers will stop fermentation early in order to leave some residual sugars and sweetness in the wine such as with dessert wines. This can be achieved by dropping fermentation temperatures to the point where the yeast are inactive, sterile filtering the wine to remove the yeast or fortification with brandy or neutral spirits to kill off the yeast cells. If fermentation is unintentionally stopped, such as when the yeasts become exhausted of available nutrients and the wine has not yet reached dryness, this is considered a stuck fermentation.
The Agaricostilbales are an order of fungi in the class Agaricostilbomycetes. The order consists of six families and 15 genera.
The Chionosphaeraceae are a family of fungi in the order Agaricostilbales. The family contains six genera. Some species form small, stilboid (pin-shaped) fruitbodies. Others are known only from their yeast states.
Saccharomyces cerevisiae virus L-A, also called L-A helper virus, is a member of the Totiviridae family of viruses found primarily in Saccharomyces cerevisiae. Its discovery in the 1970s was the main starting point of research on yeast virology. It is a ~4.6 kb double-stranded RNA virus with no extracellular phase and so is inherited through vertical cytoplasmic transmission.
