Agaricus bisporus

Common mushroom
Scientific classification
Kingdom:	Fungi
Phylum:	Basidiomycota
Class:	Agaricomycetes
Subclass:	Homobasidiomycetidae
Order:	Agaricales
Family:	Agaricaceae
Genus:	Agaricus
Species:	A. bisporus
Binomial name
Agaricus bisporus (J.E.Lange) Imbach[1]

Agaricus bisporus—known variously as the common mushroom, button mushroom, white mushroom, table mushroom, champignon mushroom, crimini mushroom, Swiss brown mushroom, Roman brown mushroom, Italian brown, Italian mushroom, cultivated mushroom, or when mature, the Portobello mushroom—is an edible basidiomycete mushroom native to grasslands in Europe and North America. Agaricus bisporus is cultivated in more than 70 countries^[2] and is one of the most commonly and widely consumed mushrooms in the world.

Agaricus bisporus
Mycological characteristics
	gills on hymenium
	cap is convex
	hymenium is free
	stipe has a ring
	spore print is brown
	ecology is saprotrophic
	edibility: choice

Taxonomy and naming

The common mushroom has a complicated taxonomic history. It was first described by English botanist Mordecai Cubitt Cooke in his 1871 Handbook of British Fungi, as a variety (var. hortensis) of Agaricus campestris.^[3][4] Danish mycologist Jakob Emanuel Lange later reviewed a cultivar specimen, and dubbed it Psalliota hortensis var. bispora in 1926.^[5] In 1938, it was promoted to species status and renamed Psalliota bispora.^[6] Emil Imbach imparted the species' current scientific name, Agaricus bisporus, after the genus Psalliota was renamed to Agaricus in 1946.^[2] The specific epithet bispora distinguishes the two-spored basidia from four-spored varieties.

Among English speakers, Agaricus bisporus is known by many names. A young specimen with a closed cap and either pale white or light brown flesh is known as a button mushroom or white mushroom. In strains with darker flesh, the immature mushroom is variously marketed as a crimini mushroom, baby portobello, baby bella, mini bella, portabellini, Roman mushroom, Italian mushroom, or brown mushroom. At this stage of maturation, the cap may also begin to open slightly. In maturity, it is called a portobello.^[7] The French name is champignon de Paris ("Paris mushroom").

The spellings "portobello", "portabella", and "portabello" are all used,^[8] but the first of these spellings is the most common.

Description

Agaricus bisporus, raw

Nutritional value per 100 g (3.5 oz)
Energy	94 kJ (22 kcal)
Carbohydrates	3.28 g
- Sugars	1.65 g
- Dietary fiber	1.0 g
Fat	0.34 g
Protein	3.09 g
Water	92.43 g
Thiamine (vit. B1)	0.081 mg (7%)
Riboflavin (vit. B2)	0.402 mg (34%)
Niacin (vit. B3)	3.607 mg (24%)
Pantothenic acid (B5)	1.497 mg (30%)
Vitamin C	2.1 mg (3%)
Iron	0.50 mg (4%)
Percentages are relative to US recommendations for adults. Source: USDA Nutrient Database

The pileus or cap of the original wild species is a pale grey-brown in color, with broad, flat scales on a paler background and fading toward the margins. It is first hemispherical in shape before flattening out with maturity, and 5–10 cm (2–4 in) in diameter. The narrow, crowded gills are free and initially pink, then red-brown and finally a dark brown with a whitish edge from the cheilocystidia. The cylindrical stipe is up to 6 cm (2⅓ in) tall by 1–2 cm wide and bears a thick and narrow ring, which may be streaked on the upperside. The firm flesh is white though stains a pale pinkish-red on bruising.^[9][10] The spore print is dark brown. The spores are oval to round and measure around 4.5–5.5 x 5–7.5 μm, and the basidia usually two-spored, although two tetrasporic varieties have been described from the Mojave desert and the Mediterranean with predominantly heterothallic and homothallic lifestyles, respectively^[11][12]

Commonly found in fields and grassy areas after rain from late spring through to autumn worldwide, especially in association with manure. It is widely collected and eaten, even by those who would not normally experiment with mushrooming.^[10]

Similar species

See also: Mushroom hunting

The common mushroom could be confused with young specimens of the deadly poisonous destroying angel (Amanita sp.), but the latter can be distinguished by their volva or cup at the base of the mushroom and pure white gills (as opposed to pinkish or brown of Agaricus bisporus). Thus it is important to always clear away debris and examine the base of a mushroom, as well as cutting open young specimens to check the gills. Furthermore, the destroying angel grows in mossy woods and lives symbiotically with spruce.

A more common and less dangerous mistake is to confuse Agaricus bisporus with Agaricus xanthodermus, an inedible mushroom found worldwide in grassy areas. Agaricus xanthodermus has an odor reminiscent of phenol; its flesh turns yellow when bruised. This fungus causes nausea and vomiting in some people.

The poisonous European species Entoloma sinuatum has a passing resemblance but has yellowish gills turning pink and lacks a ring.

Cultivation

Agaricus bisporus being cultivated.

The earliest description of the commercial cultivation of Agaricus bisporus was made by French botanist Joseph Pitton de Tournefort in 1707.^[13] French agriculturist Olivier de Serres noted that transplanting mushroom mycelia would lead to more mushrooms. Originally, cultivation was unreliable as mushroom growers would watch for good flushes of mushrooms in fields before digging up the mycelium and replanting in beds of composted manure or inoculating 'bricks' of compressed litter, loam and manure. Spawn collected this way contained pathogens and crops would be commonly infected or not grow at all.^[14]

In 1893, sterilized, or pure culture, spawn was discovered and produced by the Pasteur Institute in Paris.^[15] Today's commercial variety of the common mushroom was originally a light brown color. In 1926, a Pennsylvanian mushroom farmer found a clump of common mushrooms with white caps in his mushroom bed. Like white bread it was seen as a more attractive food item and was very popular.^[16] As was done with the navel orange and Red Delicious apple, cultures were grown from the mutant individuals, and most of the cream-colored store mushrooms we see today are products of this chance natural mutation.

Agaricus bisporus is now cultivated in at least 70 countries around the world.^[2] Global production in the early 1990s was reported to be more than 1.5 billion kg, worth more than US$ 2 billion.^[17]

Vitamin D

While Agaricus bisporus only contains 40 IU of vitamin D as ergocalciferol (vitamin D2), since they also contain high amounts of ergosterol,^{[citation needed]} by brief exposure to UV light the ergocalciferol contents rise immensely.^[18][19][20].

Potential medicinal value

Agaricus bisporus also contains sodium, potassium, and phosphorus,^[21] conjugated linoleic acid^[22] and antioxidants.^[23]

A clinical trial is scheduled to take place at the City of Hope National Medical Center due to earlier research indicating that the common mushroom can inhibit aromatase, and therefore may be able to lower estrogen levels in the human body,^[24] which might reduce breast cancer susceptibility.^{[25] [26]} A 2009 case control study of more than 2000 women correlated a large decrease of breast cancer incidence in women who consumed mushrooms. Women in the study who consumed fresh mushrooms daily were 64% less likely to develop breast cancer, while those that combined a mushroom diet with regular green tea consumption reduced their risk of breast cancer by nearly 90%.^[27]

The table mushroom has also been shown to possess possible immune system enhancing properties. An in vitro study demonstrated the mushroom enhanced dendritic cell function.^[28][29]

Health risks

Some studies have revealed that raw A. bisporus - along with some other edible mushrooms - contain small amounts of carcinogenic hydrazine derivatives, including agaritine and gyromitrin.^[30][31] However, this research also noted when cooked, these compounds were reduced significantly.^[32]

Agaricus bisporus gallery

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  Portobello mushrooms

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  Cross-section of a portobello cultivar

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  Ventral view of a portobello cultivar with a bisected stipe

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  Two Agaricus bisporus mushrooms which have fused together.

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See also

Fungi portal

• Fungiculture
• List of Agaricus species
• Medicinal mushrooms
• Effect of sunlight on mushrooms

Notes

1. ^ Imbach EJ. (1946). "Pilzflora des Kantons Luzern und der angrenzen Innerschweiz" (in German). Mitteilungen der naturforschenden Gesellschaft Luzern 15: 5–85. 
2. ^ ^{a b c} (Italian) Cappelli, Alberto (1984). Fungi Europaei:Agaricus. Saronno, Italy: Giovanna Biella. pp. 123–25. 
3. ^ Cooke MC. (1871). Handbook of British Fungi. 1. London: Macmillan and Co. p. 138. 
4. ^ "Species Fungorum - Species synonymy". Index Fungorum. CAB International. http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=531546. Retrieved 2010-01-21. 
5. ^ Lange JE. (1926). "Studies in the agarics of Denmark. Part VI. Psalliota, Russula". Dansk botanisk Arkiv 4 (12): 1–52. 
6. ^ Schäffer J, Møller FH. (1939). "Beitrag zur Psalliota Forschung" (in German). Annales Mycologici 36 (1): 64–82. 
7. ^ "Agaricus bisporus: The Button Mushroom". http://www.mushroomexpert.com/agaricus_bisporus.html. Retrieved 23 April 2011. 
8. ^ "portobello, n.2". OED Online. Oxford University Press. June 2011. http://www.oed.com/view/Entry/267736?rskey=uubXEq&result=2&isAdvanced=false. Retrieved 7 August 2011. 
9. ^ Zeitlmayr L (1976). Wild Mushrooms:An Illustrated Handbook. Garden City Press, Hertfordshire. pp. 82–83. ISBN 0-584-10324-7. 
10. ^ ^{a b} Carluccio A (2003). The Complete Mushroom Book. Quadrille. pp. 21–22. ISBN 1-84400-040-0. 
11. ^ Callac P, Billette C, Imbernon M, Kerrigan RW (1993). "Morphological, genetic, and interfertility analyses reveal a novel, tetrasporic variety of Agaricus bisporus from the Sonoran Desert of California". Mycologia 85 (5): 835–851. doi:10.2307/3760617. JSTOR 3760617. 
12. ^ Callac P, Imbernon M, Guinberteau J, Pirobe L, Granit S, Olivier JM, Theochari I (2000). "Discovery of a wild Mediterranean population of Agaricus bisporus, and its usefulness for breeding work". Mushroom Science 15: 245–252. 
13. ^ Spencer DM. (1985). "The mushroom–its history and importance". In Flegg PB, Spencer DM, Wood DA. The Biology and Technology of the Cultivated Mushroom. New York: John Wiley and Sons. pp. 1–8. ISBN 0-471-90435-X. 
14. ^ Genders 1969, p. 19
15. ^ Genders 1969, p. 18
16. ^ Genders 1969, p. 121
17. ^ Chang ST. (1993). "Mushroom biology: the impact on mushroom production and mushroom products". In Chiu S-W, Buswell J, Chang S-T. Mushroom Biology and Mushroom Products. Hong Kong: The Chinese University Press. pp. 3–20. ISBN 962-201-610-3. 
18. ^ Mushrooms and vitamin D
19. ^ Koyyalamudi SR, Jeong SC, Song CH, Cho KY, Pang G (April 2009). "Vitamin D2 formation and bioavailability from Agaricus bisporus button mushrooms treated with ultraviolet irradiation". Journal of Agricultural and Food Chemistry 57 (8): 3351–5. doi:10.1021/jf803908q. PMID 19281276. 
20. ^ Lee GS, Byun HS, Yoon KH, Lee JS, Choi KC, Jeung EB (2009). "Dietary calcium and vitamin D2 supplementation with enhanced Lentinula edodes improves osteoporosis-like symptoms and induces duodenal and renal active calcium transport gene expression in mice". European Journal of Nutrition 48 (2): 75–83. doi:10.1007/s00394-008-0763-2. PMID 19093162. 
21. ^ Benjamin, Mushrooms: poisons and panaceas, p. 67
22. ^ Chen, S.; Oh, SR; Phung, S; Hur, G; Ye, JJ; Kwok, SL; Shrode, GE; Belury, M et al. (2006). "Anti-aromatase activity of phytochemicals in white button mushrooms (Agaricus bisporus)". Cancer Res. 66 (24): 12026–34. doi:10.1158/0008-5472.CAN-06-2206. PMID 17178902. 
23. ^ Shi YL, James AE, Benzie IF, Buswell JA. (2002). "Mushroom-derived preparations in the prevention of H2O2-induced oxidative damage to cellular DNA". Teratog Carcinog Mutagen. 22 (2): 103–11. doi:10.1002/tcm.10008. PMID 11835288. 
24. ^ Chen S, Oh SR, Phung S, Hur G, Ye JJ, Kwok SL, Shrode GE, Belury M, Adams LS, Williams D (December 2006). "Anti-aromatase activity of phytochemicals in white button mushrooms (Agaricus bisporus)". Cancer Res. 66 (24): 12026–34. doi:10.1158/0008-5472.CAN-06-2206. PMID 17178902. 
25. ^ Grube BJ, Eng ET, Kao YC, Kwon A, Chen S (December 2001). "White button mushroom phytochemicals inhibit aromatase activity and breast cancer cell proliferation". J. Nutr. 131 (12): 3288–93. PMID 11739882. 
26. ^ . http://www.cityofhope.org/about/publications/eHope/2008-vol-7-num-7-july-29/Pages/a-salad-fixin-with-medical-benefits.aspx. 
27. ^ Zhang, M; Huang, J; Xie, X; Holman, CD (Mar 2009). "Dietary intakes of mushrooms and green tea combine to reduce the risk of breast cancer in Chinese women". International Journal of Cancer 124 (6): 1404–1408. doi:10.1002/ijc.24047. ISSN 0020-7136. PMID 19048616. 
28. ^ Ren Z, Guo Z, Meydani SN, Wu D (March 2008). "White button mushroom enhances maturation of bone marrow-derived dendritic cells and their antigen presenting function in mice". J. Nutr. 138 (3): 544–50. PMID 18287364. 
29. ^ Wu D, Pae M, Ren Z, Guo Z, Smith D, Meydani SN (June 2007). "Dietary supplementation with white button mushroom enhances natural killer cell activity in C57BL/6 mice". J. Nutr. 137 (6): 1472–7. PMID 17513409. 
30. ^ Hashida C, Hayashi K, Jie L, Haga S, Sakurai M, Shimizu H (June 1990). "[Quantities of agaritine in mushrooms (Agaricus bisporus) and the carcinogenicity of mushroom methanol extracts on the mouse bladder epithelium]" (in Japanese). Nippon Koshu Eisei Zasshi 37 (6): 400–5. PMID 2132000. 
31. ^ Sieger AA (ed.) (1998-01-01). "Spore Prints #338". Bulletin of the Puget Sound Mycological Society. http://www.psms.org/sporeprints/sp338.html. Retrieved 2008-10-13. 
32. ^ Agartine, Fungi.com

References

• Benjamin, Denis R. (1995). Mushrooms: poisons and panaceas—a handbook for naturalists, mycologists and physicians. New York: WH Freeman and Company. ISBN 0-7167-2600-9. 
• Genders, Roy (1969). Mushroom Growing for Everyone. London: Faber. ISBN 0-571-08992-5. 
• Kuo, M. (January 2004). "Agaricus bisporus: The common mushroom". MushroomExpert.Com. http://www.mushroomexpert.com/agaricus_bisporus.html. 
• City of Hope Research [1]

External links

• Complete common mushroom nutrition info
• Mushroom cookbook and information
• Information about a human study with Agaricus bisporus taking place at the City of Hope.
• A high-definition video of a French cave of " Champignons de Paris " closed in 2009.
• Portobello Mushroom information and recipes.