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.
Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Because yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is considered an anaerobic process. It also takes place in some species of fish where it provides energy when oxygen is scarce.
Kilju is the Finnish word for home made alcoholic beverage typically made of sugar, yeast, and water.
Saccharomyces is a genus of fungi that includes many species of yeasts. Saccharomyces is from Greek σάκχαρον (sugar) and μύκης (fungus) and means sugar fungus. Many members of this genus are considered very important in food production where they are known as brewer's yeast, baker's yeast and sourdough starter among others. They are unicellular and saprotrophic fungi. One example is Saccharomyces cerevisiae, which is used in making bread, wine, and beer, and for human and animal health. Other members of this genus include the wild yeast Saccharomyces paradoxus that is the closest relative to S. cerevisiae, Saccharomyces bayanus, used in making wine, and Saccharomyces cerevisiaevar. boulardii, used in medicine.
Saccharomycotina is a subdivision (subphylum) of the division (phylum) Ascomycota in the kingdom Fungi. It comprises most of the ascomycete yeasts. The members of Saccharomycotina reproduce by budding and they do not produce ascocarps.
Zygosaccharomyces bailii is a species in the genus Zygosaccharomyces. It was initially described as Saccharomyces bailii by Lindner in 1895, but in 1983 it was reclassified as Zygosaccharomyces bailii in the work by Barnett et al.
Cyttaria is a genus of ascomycete fungi. About 10 species belong to Cyttaria, found in South America and Australia associated with or growing on southern beech trees from the genus Nothofagus. The "llao llao" fungus Cyttaria hariotii, one of the most common fungi in Andean-Patagonian forests, has been shown to harbor the yeast Saccharomyces eubayanus, which may be source of the lager yeast S. pastorianus cold-tolerance. Cyttaria was originally described by mycologist Miles Joseph Berkeley in 1842.
Saccharomyces eubayanus, a cryotolerant type of yeast, is most likely the parent of the lager brewing yeast, Saccharomyces pastorianus.
Hanseniaspora is a genus of yeasts. The name Kloeckera is applied to its anamorph form. They are typically apiculate (lemon-shaped) in shape and often found in grape musts pre-fermentation.
Hanseniaspora guilliermondii is a species of yeast in the family Saccharomycetaceae. In its anamorph form, it is called Kloeckera apis.
Aerobic fermentation or aerobic glycolysis is a metabolic process by which cells metabolize sugars via fermentation in the presence of oxygen and occurs through the repression of normal respiratory metabolism. Preference of aerobic fermentation over aerobic respiration is referred to as the Crabtree effect in yeast, and is part of the Warburg effect in tumor cells. While aerobic fermentation does not produce adenosine triphosphate (ATP) in high yield, it allows proliferating cells to convert nutrients such as glucose and glutamine more efficiently into biomass by avoiding unnecessary catabolic oxidation of such nutrients into carbon dioxide, preserving carbon-carbon bonds and promoting anabolism.
Kazachstania yasuniensis is a recently isolated yeast. This organism is part of the genus Kazachstania, which can be found in a large variety of habitats such as fermented foods, animals, wastewater, et cetera.
Hanseniaspora clermontiae is a species of yeast in the family Saccharomycetaceae. It was first isolated from stem rot occurring in a lobelioid plant in Hawaii, and may be endemic to the Hawaiian Islands.
Hanseniaspora lachancei is a species of yeast in the family Saccharomycetaceae. It is associated with fermenting agave juice and a tequila production facility in Mexico.
Hanseniaspora opuntiae is a species of yeast in the family Saccharomycetaceae. It has been isolated from locations worldwide, on grape berries and on prickly pear cacti.
Hanseniaspora meyeri is a species of yeast in the family Saccharomycetaceae. Samples of the species have been obtained worldwide from flowers, fruit flies, stem rot, and spoiled grape punch.
Hanseniaspora occidentalis is a species of yeast in the family Saccharomycetaceae. In its anamorph form, it was called Kloeckera javanica. It has been isolated in the wild from soil samples and vineyards. Samples of a variant have been isolated from orange juice and rotten oranges. It has demonstrated potential as an organism to reduce malic acid in wine production.
Hanseniaspora osmophila is a species of yeast in the family Saccharomycetaceae. It is found in soil and among the bark, leaves, and fruits of plants, as well as fermented foods and beverages made from fruit.
Hanseniaspora pseudoguilliermondii is a species of yeast in the family Saccharomycetaceae. Originally isolated from orange juice concentrate, it has been found on fruit and fruit juices in locations around the world. It has also been observed forming hybrids with Hanseniaspora opuntiae.
Zygosaccharomyces rouxii is a species of yeast in the genus Zygosaccharomyces. Initially described as Saccharomyces rouxii by Boutroux in 1883, it was then moved to the genus Zygosaccharomyces in the work of Barnett et al. It is remarkably tolerant of high concentrations of sugar or salt, making it a spoilage agent of otherwise stable foods, but also present in fermentation of products such as soy sauce or balsamic vinegar.
