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Brown Blotch Disease
Brown blotch disease is a bacterial infection that affects nearly every species of mushroom. The infecting bacteria, Pseudomonas tolaasii, produces the toxin tolaasin that causes brown spots to cover the surface of the mushroom. Brown blotch disease is especially problematic on common mushroom farms, where it can spread quickly and cause huge economic losses. Symptoms Agaricus bisporus, or the cultivated mushroom, is the primary victim of brown blotch disease. The most common symptom of brown blotch disease in A. bisporus is the formation of round lesions on the cap and stalk of the mushroom. As the disease progresses, these lesions go from a pale yellow to a dark brown and cause the quick deterioration of mushrooms after harvest. Any external growth such as the fruit bodies (spore-producing structures) formed by infected mushrooms are completely brown. In minor cases of brown blotch disease, there are a few brown spots on the cap or stalk of the mushroom. In major cases, ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mushroom
A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is the cultivated white button mushroom, ''Agaricus bisporus''; hence the word "mushroom" is most often applied to those fungi ( Basidiomycota, Agaricomycetes) that have a stem ( stipe), a cap ( pileus), and gills (lamellae, sing. lamella) on the underside of the cap. "Mushroom" also describes a variety of other gilled fungi, with or without stems, therefore the term is used to describe the fleshy fruiting bodies of some Ascomycota. These gills produce microscopic spores that help the fungus spread across the ground or its occupant surface. Forms deviating from the standard morphology usually have more specific names, such as "bolete", "puffball", "stinkhorn", and " morel", and gilled mushrooms themselves are often called "agarics" in refere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudomonas Tolaasii
''Pseudomonas tolaasii'' is a species of Gram-negative soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ... bacteria that is the causal agent of bacterial blotch on cultivated mushrooms (''Agaricus bisporus''). It is known to produce a toxin, called tolaasin, which is responsible for the brown blotches associated with the disease. It also demonstrates hemolytic activity, causing lysis of erythrocytes. Based on 16S rRNA analysis, ''P. tolaasii'' has been placed in the ''Pseudomonas fluorescens, P. fluorescens'' group. References External linksType strain of ''Pseudomonas tolaasii'' at Bac''Dive'' - the Bacterial Diversity Metadatabase Pseudomonadales Bacteria described in 1919 {{Pseudomonadales-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tolaasin
Tolaasin, a toxic secretion by ''Pseudomonas tolaasii'', is the cause of bacterial brown blotch disease of edible mushrooms. Tolaasin is composed of 18 amino acids, including a beta-hydroxy-octanoic acid chain located at the N terminus. Tolaasin is a 1985 Da lipodepsipeptide non-host specific toxin. In addition to forming an amphipathic left handed alpha-helix in a hydrophobic environment, the toxin has been shown to form Zn2+-sensitive voltage-gated ion channels in planar lipid bilayers and to catalyze erythrocyte lysis Lysis ( ) is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ''lysate''. In molecular bio ... by a colloid osmotic mechanism. At high concentrations, tolaasin acts as a detergent that is able to directly dissolve eukaryotic membranes. The fungal cell membranes are disrupted by the lipopeptides through the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fungiculture
Fungiculture is the cultivation of fungi such as mushrooms. Cultivating fungi can yield foods (which include mostly mushrooms), medicine, construction materials and other products. A ''mushroom farm'' is involved in the business of growing fungi. The word is also commonly used to refer to the practice of cultivation of fungi by animals such as leafcutter ants, termites, ambrosia beetles, and marsh periwinkles. Overview Mushrooms are not plants, and require different conditions for optimal growth. Plants develop through photosynthesis, a process that converts atmospheric carbon dioxide into carbohydrates, especially cellulose. While sunlight provides an energy source for plants, mushrooms derive all of their energy and growth materials from their growth medium, through biochemical decomposition processes. This does not mean that light is an irrelevant requirement, since some fungi use light as a signal for fruiting. However, all the materials for growth must already be pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agaricus Bisporus
''Agaricus bisporus'' is an edible basidiomycete mushroom native to grasslands in Eurasia and North America. It has two color states while immature – white and brown – both of which have various names, with additional names for the mature state. ''A. bisporus'' is cultivated in more than seventy countries and is one of the most commonly and widely consumed mushrooms in the world. Names When immature and , this mushroom may be known as: * common mushroom * white mushroom * button mushroom * cultivated mushroom * table mushroom * champignon ( French for mushroom) When immature and , it may be known variously as: * Swiss brown mushroom * Roman brown mushroom * Italian brown mushroom * cremini/crimini mushroom * chestnut mushroom (not to be confused with '' Pholiota adiposa'') * baby bella When marketed in its mature state, the mushroom is brown with a cap measuring . This form is commonly sold under the names portobello, portabella, or portobella; the etymology is dispute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporocarp (fungi)
The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cycle, while the rest of the life cycle is characterized by vegetative mycelial growth and asexual spore production. The sporocarp of a basidiomycete is known as a ''basidiocarp'' or ''basidiome'', while the fruitbody of an ascomycete is known as an '' ascocarp''. Many shapes and morphologies are found in both basidiocarps and ascocarps; these features play an important role in the identification and taxonomy of fungi. Fruitbodies are termed ''epigeous'' if they grow on the ground, while those that grow underground are ''hypogeous''. Epigeous sporocarps that are visible to the naked eye, especially fruitbodies of a more or less agaricoid morphology, are often called mushrooms. Epigeous sporocarps have mycelia that extend underground far ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relative Humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depends on the temperature and pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is the dew point. The amount of water vapor needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 g of water per cubic metre of air at , but only 8 g of water per cubic metre of air at . Three primary measurements of humidity are widely employed: absolute, relative, and specific. Ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogenic Bacteria
Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often Probiotic, beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred. By contrast, several thousand species are part of the gut flora present in the digestive tract. The body is continually exposed to many species of bacteria, including beneficial commensals, which grow on the skin and mucous membranes, and saprophytes, which grow mainly in the soil and in decomposition, decaying matter. The blood and tissue fluids contain nutrients sufficient to sustain the growth of many bacteria. The body has defence mechanisms that enable it to resist microbial invasion of its tissues and give it a natural immune system, immunity or innate immunity, innate resistance against many microorganisms. Pathogenic bacteria are specially adapt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saprotrophic Nutrition
Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (for example ''Mucor'') and soil bacteria. Saprotrophic microscopic fungi are sometimes called saprobes; saprotrophic plants or bacterial flora are called saprophytes ( sapro- 'rotten material' + -phyte 'plant'), although it is now believed that all plants previously thought to be saprotrophic are in fact parasites of microscopic fungi or other plants. The process is most often facilitated through the active transport of such materials through endocytosis within the internal mycelium and its constituent hyphae. states the purpose of saprotrophs and their internal nutrition, as well as the main two types of fungi that are most often referred to, as well as describes, visually, the process of saprotrophic nutrition through a diagram of hy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exponential Growth
Exponential growth is a process that increases quantity over time. It occurs when the instantaneous rate of change (that is, the derivative) of a quantity with respect to time is proportional to the quantity itself. Described as a function, a quantity undergoing exponential growth is an exponential function of time, that is, the variable representing time is the exponent (in contrast to other types of growth, such as quadratic growth). If the constant of proportionality is negative, then the quantity decreases over time, and is said to be undergoing exponential decay instead. In the case of a discrete domain of definition with equal intervals, it is also called geometric growth or geometric decay since the function values form a geometric progression. The formula for exponential growth of a variable at the growth rate , as time goes on in discrete intervals (that is, at integer times 0, 1, 2, 3, ...), is x_t = x_0(1+r)^t where is the value of at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypha
A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or more cells surrounded by a tubular cell wall. In most fungi, hyphae are divided into cells by internal cross-walls called "septa" (singular septum). Septa are usually perforated by pores large enough for ribosomes, mitochondria, and sometimes nuclei to flow between cells. The major structural polymer in fungal cell walls is typically chitin, in contrast to plants and oomycetes that have cellulosic cell walls. Some fungi have aseptate hyphae, meaning their hyphae are not partitioned by septa. Hyphae have an average diameter of 4–6 µm. Growth Hyphae grow at their tips. During tip growth, cell walls are extended by the external assembly and polymerization of cell wall components, and the internal production of new cell membrane. The S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surfactant
Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, or dispersants. The word "surfactant" is a blend of ''surface-active agent'', coined . Agents that increase surface tension are "surface active" in the literal sense but are not called surfactants as their effect is opposite to the common meaning. A common example of surface tension increase is salting out: by adding an inorganic salt to an aqueous solution of a weakly polar substance, the substance will precipitate. The substance may itself be a surfactant – this is one of the reasons why many surfactants are ineffective in sea water. Composition and structure Surfactants are usually organic compounds that are amphiphilic, meaning each molecule contains both a hydrophilic "water-seeking" group (the ''head''), and a hydro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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