Pleurotus ostreatus

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Pleurotus ostreatus
Oyster mushroom in the Havré wood, Belgium
Scientific classification
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Pleurotaceae
Genus: Pleurotus
Species: P. ostreatus
Binomial name
Pleurotus ostreatus
(Jacq. ex Fr.) P.Kumm. 1871[1]
Pleurotus ostreatus
View the Mycomorphbox template that generates the following list Mycological characteristics
gills on hymenium
cap is offset
hymenium is decurrent
stipe is bare
spore print is white
ecology is saprotrophic
edibility: choice

Pleurotus ostreatus, the oyster mushroom, is a common edible mushroom. It was first cultivated in Germany as a subsistence measure during World War I[2] and is now grown commercially around the world for food. However, the first documented cultivation was by Kaufert.[3] There is some question about the name Pleurotus corticatus, but no question that he cultivated an oyster mushroom. It is related to the similarly cultivated "king oyster mushroom". Oyster mushrooms can also be used industrially for mycoremediation purposes. The oyster mushroom may be considered a medicinal mushroom, since it contains statins such as lovastatin which work to reduce cholesterol.[4]

The oyster mushroom is one of the more commonly sought wild mushrooms, though it can also be cultivated on straw and other media. It often has the scent of anise due to the presence of benzaldehyde (which, however, smells more like almonds).[5]

Name

Both the Latin and common names refer to the shape of the fruiting body. The Latin pleurotus (sideways) refers to the sideways growth of the stem with respect to the cap, while the Latin ostreatus (and the English common name, oyster) refers to the shape of the cap which resembles the bivalve of the same name. Many also believe that the name is fitting due to a flavor resemblance to oysters.

The name Oyster mushroom is also applied to other Pleurotus species, so P. ostreatus is sometimes referred to as the Tree Oyster Mushroom[6] or the Grey Oyster Mushroom[7] to differentiate it from other species in the genus. Mycologist Paul Stamets uses the name Tree Oyster Mushroom and also includes the following common names for the species in his book Growing gourmet and medicinal mushrooms:[6]

  • Oyster Shelf
  • Tree Oyster
  • Straw Mushroom
  • Hiratake ("Flat Mushroom" in Japanese)
  • Tamogitake

In Chinese, they are called píng gū (平菇; literally "flat mushroom"). In Vietnam, the mushroom is known as nấm sò or nấm bào ngư. It is called chippikkoon (ചിപ്പിക്കൂൺ) in Malayalam. In Iran it is called "Sadafi" ("sadaf" meaning oyster in Persian).[8]

Description

Details of the gill structure

The mushroom has a broad, fan or oyster-shaped cap spanning 5–25 cm; natural specimens range from white to gray or tan to dark-brown; the margin is inrolled when young, and is smooth and often somewhat lobed or wavy. The flesh is white, firm, and varies in thickness due to stipe arrangement. The gills of the mushroom are white to cream, and descend on the stalk if present. If so, the stipe is off-center with a lateral attachment to wood. The spore print of the mushroom is white to lilac-gray, and best viewed on dark background. The mushroom's stipe is often absent. When present, it is short and thick.

Omphalotus nidiformis is a toxic lookalike found in Australia and Japan. In North America, Omphalotus olivascens, the western jack-o'-lantern mushroom and Clitocybe dealbata, the ivory funnel mushroom, both bear a resemblance to Pleurotus ostreatus. Both Omphalotus olivascens and Clitocybe dealbata contain muscarine and are toxic.

Habitat

Oyster mushroom on a tree

The oyster mushroom is widespread in many temperate and subtropical forests throughout the world, although it is absent from the Pacific Northwest of North America, being replaced by P. pulmonarius and P. populinus.[9] It is a saprotroph that acts as a primary decomposer of wood, especially deciduous trees, and beech trees in particular.[10] It is a white-rot wood-decay fungus.

The oyster mushroom is one of the few known carnivorous mushrooms. Its mycelia can kill and digest nematodes, which is believed to be a way in which the mushroom obtains nitrogen.

The standard oyster mushroom can grow in many places, but some other related species, such as the branched oyster mushroom, grow only on trees.

While this mushroom is often seen growing on dying hardwood trees, it only appears to be acting 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.[11] Despite this, the belief that P. ostreatus could damage New Zealand's forestry industry has led New Zealand to ban its importation.[7]

Culinary uses

The oyster mushroom is frequently used in Japanese, Korean and Chinese cookery as a delicacy: it is frequently served on its own, in soups, stuffed, or in stir-fry recipes with soy sauce. Oyster mushrooms are sometimes made into a sauce, used in Asian cooking, which is similar to oyster sauce. The mushroom's taste has been described as a mild with a slight odor similar to anise. The oyster mushroom is best when picked young; as the mushroom ages, the flesh becomes tough and the flavor becomes acrid and unpleasant.

Oyster mushrooms are widely cultivated and used in Kerala, India where a wide variety of dishes are prepared from them. Oyster mushrooms are mainly cultivated in large clear polyethylene bags with buns of hay layered in the bags, and spores sown between these layers.

Oyster mushrooms contain small amounts of arabitol, a sugar alcohol, which may cause gastrointestinal upset in some people.

Non-culinary uses

A US company, Ecovative Design, has proposed using the mycelium along with the growing substrate as a substitute for petroleum derived expanded polystyrene packing material or as an insulating material.[12] It may also be used to absorb and digest oil spills and other petroleum produces. Researchers in Mexico have shown that oyster mushrooms can break down disposable diapers.[13]

Oyster mushrooms and lovastatin

In vivo research has shown that consumption of oyster mushrooms lowers cholesterol levels,[14] because these mushrooms naturally contain lovastatin.[4] Studies have shown they contain up to 2.8% lovastatin on a dry weight basis.[15]

Gallery

  • Pleurotus.ostreatus.spores.1000x.jpg
  • Pleurotus.ostreatus.400x.phase.contrast.JPG
  • OysterPrint.jpg
  • Harvestingoystermushroomcultivatedinbaggedsawdustmixture.jpg
  • Oyster mushoom fells.jpg
  • Oyster mushroom log.jpg
  • Many Oyster Mushrooms MontMD.jpg
  • Pleurotus ostreatus JPG1.jpg
  • Pleurotus ostreatus JPG4.jpg
  • Oyster mushroom.JPG

References

  1. ↑ Kummer, P. (1871). Der Führer in die Pilzkunde (1st ed.). 
  2. ↑ Eger, G., Eden, G. & Wissig,E. (1976).Pleurotus ostreatus – breeding potential of a new cultivated mushroom. Theoretical and Applied Genetics 47: 155–163.
  3. ↑ Kaufert, F. (1936) The biology of Pleurotus corticatus Fries. Minnesota Agricultural Experiment Station Bulletin 114.
  4. ↑ 4.0 4.1 Gunde-Cimerman N, Cimerman A. (Mar 1995). "Pleurotus fruiting bodies contain the inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase-lovastatin.". Exp Mycol. 19 (1): 1–6. doi:10.1006/emyc.1995.1001. PMID 7614366. 
  5. ↑ 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. 
  6. ↑ 6.0 6.1 Stamets, Paul (2000). "Chapter 21: Growth Parameters for Gourmet and Medicinal Mushroom Species". Growing gourmet and medicinal mushrooms = [Shokuyo oyobi yakuyo kinoko no sabai] (3rd ed.). Berkeley, California, USA: Ten Speed Press. pp. 308–315. ISBN 978-1-58008-175-7. 
  7. ↑ 7.0 7.1 Hall, Ian R. (April 2010). "Growing mushrooms: the commercial reality" (PDF). Lifestyle Farmer (Auckland, New Zealand: Rural Press): 42–45. Retrieved 26 January 2012. 
  8. ↑ Asef, M.R. 2012. Intersterility groups of Pleurotus ostreatus complex in Iran. Mycology (in press) DOI: 10.1080/21501203.2012.659683
  9. ↑ Trudell, S.; Ammirati, J. (2009). Mushrooms of the Pacific Northwest. Timber Press Field Guides. Portland, Oregon: Timber Press. p. 134. ISBN 0-88192-935-2. 
  10. ↑ Phillips, Roger (2006), Mushrooms. Pub. McMilan, ISBN 0-330-44237-6. P. 266.
  11. ↑ Stamets, Paul (2000). "Chapter 2: The Role of Mushrooms in Nature". Growing gourmet and medicinal mushrooms = [Shokuyo oyobi yakuyo kinoko no sabai] (3rd ed.). Berkeley, California, USA: Ten Speed Press. pp. 10–11. ISBN 978-1-58008-175-7. 
  12. ↑ http://www.thisoldhouse.com/toh/article/0,,20153687,00.html
  13. ↑ http://news.discovery.com/earth/tasty-mushrooms-from-dirty-diapers-110615.htm
  14. ↑ Rop O, Mlcek J, Jurikova T. (2009). "Beta-glucans in higher fungi and their health effects". Nutrition Reviews 67 (11): 624–31. doi:10.1111/j.1753-4887.2009.00230.x. PMID 19906249. 
  15. ↑ Production and Purification of Statins from Pleurotus ostreatus (Basidiomycetes) Strains. 2003. 

Further reading

Books
  • Lincoff, G.H. (1981). National Audubon Society Field Guide to North American Mushrooms. Knopf. ISBN 978-0-394-51992-0
  • Spahr, D.L. (2009). Edible and Medicinal Mushrooms of New England and Eastern Canada. North Atlantic Books. ISBN 978-1-55643-795-3
  • Stamets, P. (2000). Growing Gourmet and Medicinal Mushrooms (3. edition). Ten Speed Press. ISBN 978-1-58008-175-7

External links

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