Pleurotus ostreatus (commonly known theoyster mushroom,[2]grey oyster mushroom,[3]oyster fungus,hiratake, orpearl oyster mushroom). Found in temperate and subtropical forests around the world, it is a popularedible mushroom.
Both theLatin andcommon names refer to the shape of the fruiting body.[4] The Latinpleurotus (side-ear) refers to the sideways growth of the stem with respect to the cap, while the Latinostreatus (and the English common name,oyster) refers to the shape of the cap which resembles the bivalve of the same name.[4] The oyster reference may also derive from the slippery texture of the mushroom.[4]
Thecap is broad, fan or oyster-shaped, and 2–30 centimetres (1–12 inches) wide.[5] In the wild, it ranges from white to gray or brown; the margin is inrolled when young, smooth and often somewhat lobed or wavy. Theflesh is white, firm, and varies in thickness due tostipe arrangement. The stipe, if present, is up to 4 cm (1+1⁄2 in) long and thick,[2] off-center and attaching laterally to wood. Thegills are whitish, sometimes becoming yellowish, and decurrent if a stalk is present.[2] Thespore print is white to lilac-gray, and best viewed on a dark background. The mushroom has the bittersweet aroma ofbenzaldehyde or bitter almonds.[6]
Oyster mushrooms on a treeDetails of the gill structure
Omphalotus nidiformis is a toxic lookalike found in Australia. In North America, potential lookalikes include the toxicmuscarine-containingO. olivascens (the western jack-o'-lantern mushroom) andClitocybe dealbata (the ivory funnel mushroom). Some toxicLentinellus species are similar in appearance, but have gills with jagged edges and finely haired caps.[8]
The oyster mushroom is widespread in many temperate and subtropical forests throughout the world, although it is absent from thePacific Northwest ofNorth America, being replaced byP. pulmonarius andP. populinus.[9] It is asaprotroph that acts as a primary decomposer of wood, especially deciduous trees, and beech trees in particular.[10] It is awhite-rot wood-decay fungus.
The oyster mushroom can be found in many habitats, year round in theUnited Kingdom, while some related species (e.g. the branched oyster mushroom) grow only on trees.[11]
While this mushroom is often seen growing on dying hardwood trees, it only appears to be actingsaprophytically, rather than parasitically. As the tree dies of other causes,P. ostreatus grows on the rapidly increasing mass of dead and dying wood. They actually benefit the forest by decomposing the dead wood, returning vital elements and minerals to the ecosystem in a form usable to other plants and organisms.[4] Additionally, oyster mushroomsbioaccumulatelithium.[12]
Predatory behavior on nematodes has evolved independently in all major fungal lineages.[13]P. ostreatus is one of at least 700 knownnematophagous mushrooms.[14] Itsmycelia can kill and digestnematodes, which is believed to be a way in which the mushroom obtainsnitrogen.[13]
Commercialcultivation of this mushroom first began in Germany as a subsistence measure duringWorld War I,[15] and it is now grown commercially around the world for food.
The oyster mushroom is a choiceedible.[5] Oyster mushrooms are used inCzech,Polish, andSlovak contemporary cuisine in soups and stews in a similar fashion to meat, as well as breaded to become a vegetarian alternative to thekotlet in Polish dishes.[16][17] It is adelicacy inJapanese,Korean andChinese cuisine.[citation needed] It is frequently served on its own, in soups, stuffed, or instir-fry recipes withsoy sauce. Oyster mushrooms may be used in sauces, such asvegetarian oyster sauce. The mushroom's taste has been described as mild with a slight odor similar toanise. It is best when picked young; as the mushroom ages, the flesh becomes tough and the flavor becomes acrid.[18]
Oyster mushrooms can also be used industrially formycoremediation purposes. Oyster mushrooms were used to treat soil that had been polluted with diesel oil. The mushroom was able to convert 95% of the oil into non-toxic compounds.[19]P. ostreatus is also capable of growing upon and degradingoxo-biodegradable plastic bags;[20] it can also contribute to the degradation ofrenewable polyethylene.[21]
The species has been found to contain the cholesterol-lowering druglovastatin.[22]
^Beltran-Garcia, Miguel J.; Estarron-Espinosa, Mirna; Ogura, Tetsuya (1997). "Volatile Compounds Secreted by the Oyster Mushroom (Pleurotus ostreatus) and Their Antibacterial Activities".Journal of Agricultural and Food Chemistry.45 (10): 4049.doi:10.1021/jf960876i.
^Eger G, Eden G, Wissig E (July 1976). "Pleurotus Ostreatus - breeding potential of a new cultivated mushroom".Theor Appl Genet.47 (4):155–63.doi:10.1007/BF00278373.PMID24414617.
