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Osmophilic
An osmophile is a microorganism adapted to environments with high osmotic pressures, such as high sugar concentrations. Osmophiles are similar to halophiles (salt-loving organisms) in that a critical aspect of both types of environment is their low water activity, aW. High sugar concentrations represent a growth-limiting factor for many microorganisms, yet osmophiles protect themselves against this high osmotic pressure by the synthesis of osmoprotectants such as alcohols and amino acids. Many osmophilic microorganisms are yeast 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 constit ...s; some bacteria are also osmophilic. Osmophilic yeasts are important because they cause spoilage in the sugar and sweet goods industry, with products such as fruit juices, fruit juice concentrates, liquid s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wallemia Sebi
''Wallemia sebi'' is a xerophilic fungus of the phylum Basidiomycota. It is commonly found on highly sugared or salted materials, such as jams, bread, cakes, sugar, bacon, salted meats, and salted fish. It is also found in indoor air, house dust, and soil. One distinctive feature of ''W. sebi'' is its relationship with water activity. Most fungi are profoundly affected by the availability of water. The ability to tolerate environments with low water activity has been found mostly in Ascomycota, but rarely in Basidiomycota. However, ''W. sebi.'' can adjust its morphology and physiology to adapt to different environmental conditions and survive osmotic stress. ''Wallemia sebi'' have lower limits for growth below water activity of 0.75 (0.69-0.75) aw, while most microorganisms are limited to 0.95 and above. ''Wallemia sebi'' has been isolated from hair, hay, textiles and man. It can grow slowly without additional solute in the growth medium, and form small, reddish-brown, powde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmotic Pressure
Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in a pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane. Osmosis occurs when two solutions containing different concentrations of solute are separated by a selectively permeable membrane. Solvent molecules pass preferentially through the membrane from the low-concentration solution to the solution with higher solute concentration. The transfer of solvent molecules will continue until equilibrium is attained. Theory and measurement Jacobus van 't Hoff found a quantitative relationship between osmotic pressure and solute concentration, expressed in the following equation: :\Pi = icRT where \Pi is osmotic p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halophile
The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, such as the alga ''Dunaliella salina'' and fungus ''Wallemia ichthyophaga''. Some well-known species give off a red color from carotenoid compounds, notably bacteriorhodopsin. Halophiles can be found in water bodies with salt concentration more than five times greater than that of the ocean, such as the Great Salt Lake in Utah, Owens Lake in California, the Urmia Lake in Iran, the Dead Sea, and in evaporation ponds. They are theorized to be a possible analogues for modeling extremophiles that might live in the salty subsurface water ocean of Jupiter's Europa and similar moons. Classification Halophiles are categorized by the extent of their halotolerance: slight, moderate, or extreme. Slight halophiles prefer 0.3 to 0.8 M (1.7 to 4.8% ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Activity
Water activity (''aw'') is the partial vapor pressure of water in a solution divided by the standard state partial vapor pressure of water. In the field of food science, the standard state is most often defined as pure water at the same temperature. Using this particular definition, pure distilled water has a water activity of exactly one. Water activity is the thermodynamic activity of water as solvent and the relative humidity of the surrounding air after equilibration. As temperature increases, ''aw'' typically increases, except in some products with crystalline salt or sugar. Water migrates from areas of high ''aw'' to areas of low ''aw''. For example, if honey (''aw'' ≈ 0.6) is exposed to humid air (''aw'' ≈ 0.7), the honey absorbs water from the air. If salami (''aw'' ≈ 0.87) is exposed to dry air (''aw'' ≈ 0.5), the salami dries out, which could preserve it or spoil it. Lower ''aw'' substances tend to support fewer microorganisms since these get desiccated by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Growth-limiting Factor
A limiting factor is a variable of a system that causes a noticeable change in output or another measure of a type of system. The limiting factor is in a pyramid shape of organisms going up from the producers to consumers and so on. A factor not limiting over a certain domain of starting conditions may yet be limiting over another domain of starting conditions, including that of the factor. Overview The identification of a factor as limiting is possible only in distinction to one or more other factors that are non-limiting. Disciplines differ in their use of the term as to whether they allow the simultaneous existence of more than one limiting factor which (may then be called "co-limiting"), but they all require the existence of at least one non-limiting factor when the terms are used. There are several different possible scenarios of limitation when more than one factor is present. The first scenario, called ''single limitation'' occurs when only one factor, the one with maximum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmoprotectant
Osmoprotectants or compatible solutes are small organic molecules with neutral charge and low toxicity at high concentrations that act as osmolytes and help organisms survive extreme osmotic stress. Osmoprotectants can be placed in three chemical classes: betaines and associated molecules, sugars and polyols, and amino acids. These molecules accumulate in cells and balance the osmotic difference between the cell's surroundings and the cytosol. In plants, their accumulation can increase survival during stresses such as drought. In extreme cases, such as in bdelloid rotifers, tardigrades, brine shrimp, and nematodes, these molecules can allow cells to survive being completely dried out and let them enter a state of suspended animation called cryptobiosis. Intracellular osmoprotectant concentrations are regulated in response to environmental conditions such as osmolarity and temperature via regulation of specific transcription factors and transporters. They have been shown to play a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcohol (chemistry)
In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic drinks. An important class of alcohols, of which methanol and ethanol are the simplest examples, includes all compounds which conform to the general formula . Simple monoalcohols that are the subject of this article include primary (), secondary () and tertiary () alcohols. The suffix ''-ol'' appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority. When a higher priority group is present in the compound, the prefix ''hydroxy-'' is used in its IUPAC name. The suffix ''-ol'' in non-IUPAC names (such as paracetamol or cholesterol) also typically indicates that the substance is an alcohol. However, some compou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha amino acids appear in the genetic code. Amino acids can be classified according to the locations of the core structural functional groups, as Alpha and beta carbon, alpha- , beta- , gamma- or delta- amino acids; other categories relate to Chemical polarity, polarity, ionization, and side chain group type (aliphatic, Open-chain compound, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yeast
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. Yeasts are unicellular organisms that 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. With their single-celled growth habit, yeasts can be contrasted with molds, which grow hyphae. Fungal species that can take both forms (depending on temperature or other conditions) are ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccharomyces Rouxii
''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. It is known as the brewer's yeast or baker's yeast. 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 cerevisiae'' var. ''boulardii'', used in medicine. Morphology Colonies of ''Saccharomyces'' grow rapidly and mature in three days. They are flat, smooth, moist, glistening or dull, and cream in color. The inability to use nitrate and ability to ferment various carbohydrates are typical characteristics of ''Sacc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccharomyces Bailii
''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. It is known as the brewer's yeast or baker's yeast. 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 cerevisiae'' var. ''boulardii'', used in medicine. Morphology Colonies of ''Saccharomyces'' grow rapidly and mature in three days. They are flat, smooth, moist, glistening or dull, and cream in color. The inability to use nitrate and ability to ferment various carbohydrates are typical characteristics of ''Sacc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debaryomyces
''Debaryomyces'' is a genus of yeasts in the family Saccharomycetaceae The Saccharomycetaceae are a family of yeasts in the order Saccharomycetales that reproduce by budding. Species in the family have a cosmopolitan distribution, and are present in a wide variety of habitats, especially those with a plentiful suppl .... Species *'' D. artagaveytiae'' *'' D. carsonii'' *'' D. castellii'' *'' D. coudertii'' *'' D. etchellsii'' *'' D. globularis'' *'' D. hansenii'' *'' D. kloeckeri'' *'' D. kursanovii'' *'' D. marama'' *'' D. macquariensis'' *'' D. melissophilus'' *'' D. mrakii'' *'' D. mycophilus'' *'' D. nepalensis'' *'' D. occidentalis'' *'' D. oviformis'' *'' D. polymorphus'' *'' D. prosopidis'' *'' D. pseudopolymorphus'' *'' D. psychrosporus'' *'' D. robertsiae'' *'' D. singareniensis'' *'' D. udenii'' *'' D. vanrijiae'' *'' D. vietnamensis'' *'' D. vindobonensis'' *'' D. yamadae'' References Saccharomycetaceae Yeasts Osmophiles {{yeast-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
