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Agaricus bisporus

life science Maturity 11-13 Next article →

The mushroom known scientifically as Agaricus bisporus is a basidiomycete fungus. It is one of the most widely consumed mushrooms on our planet. This species is native to the grasslands of Eurasia and North America. Today, it is cultivated in more than 70 different countries. It is a vital part of the global food system. In 2022, total world production of mushrooms and truffles reached 48 million tonnes. China led this production, accounting for 94% of the total amount.

2011-06-25 Agaricus bisporus 3 70149
2011-06-25 Agaricus bisporus 3 70149

This mushroom has several different names depending on its age and color. When it is immature and white, people call it a button mushroom or a champignon. If it is immature and brown, it is often called a cremini, chestnut, or baby bella mushroom. When the mushroom reaches its fully mature state, it is known as a portobello. The physical appearance changes as it grows. The pileus, or cap, starts as a hemisphere. As the mushroom matures, the cap flattens out. The cylindrical stipe, which is the stem, can grow quite tall. It often features a thick, narrow ring near the top.

The internal parts of the mushroom also change with age. Underneath the cap, there are many crowded gills. These gills begin as a pink color in young specimens. As the mushroom develops, the gills turn red-brown. Finally, they become dark brown with a whitish edge. This edge comes from structures called cheilocystidia. The flesh of the mushroom is firm and white. However, the flesh will stain a pale pinkish-red if it is bruised. The spores produced by the mushroom are dark brown. These spores are oval or round and are very small. They measure approximately 4.5 to 5.5 micrometers by 5 to 7.5 micrometers.

Scientists have had a complex history of naming this species. In 1871, the English botanist Mordecai Cubitt Cooke first described it. He originally classified it as a variety of Agaricus campestris. In 1926, the Danish mycologist Jakob Emanuel Lange reviewed a specimen. He named it Psalliota hortensis var. bispora. By 1938, it was promoted to its own species status. The current name, Agaricus bisporus, was provided by Emil Imbach. He named it after the genus Psalliota was renamed to Agaricus in 1946. The name bisporus refers to the two-spored basidia, which are the cells that hold the spores. While most have two spores, some varieties in the Mojave Desert or the Mediterranean have four.

Humans have been trying to grow these mushrooms for a long time. In 1707, Joseph Pitton de Tournefort wrote about commercial cultivation. Early farmers would find wild mycelia in the fields. Mycelia are the underground networks of the fungus. They would dig up this material and replant it in composted manure. This method was often unreliable because the crops would get sick from pathogens. In 1893, the Pasteur Institute in Paris changed everything. They produced sterilized, or pure culture, spawn. This allowed farmers to grow much healthier crops on composted horse manure.

A famous discovery happened in 1925 at the Keystone Mushroom Farm. The owner, Louis Ferdinand Lambert, found a white mushroom growing in a bed of brown ones. This was a natural mutation. He brought the specimen to his laboratory to study it. Because white mushrooms were seen as more attractive, they became very popular. Most cream-colored mushrooms sold in stores today come from that single mutation.

Eating Agaricus bisporus provides many important nutrients. The mushroom is 92% water, 3% carbohydrates, and 3% protein. It contains very little fat. It is an excellent source of B vitamins, including riboflavin, niacin, and pantothenic acid. It also provides minerals like potassium and phosphorus. Interestingly, the vitamin D content changes with light. Fresh mushrooms only have 0.2 micrograms of vitamin D per 100 grams. However, exposure to UV light can increase this to 11.2 micrograms.

It is important to be careful when looking for these in the wild. Some poisonous mushrooms can look very similar. For example, the Amanita genus contains "destroying angels." These are lethal mushrooms that can be confused with young Agaricus bisporus. You can tell them apart because destroying angels have a volva, or cup, at the base. They also have pure white gills instead of pink or brown gills. Another common mistake is confusing them with A. xanthodermus. This inedible mushroom smells like phenol and turns yellow when bruised.

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