Pholiota microspora
What You Should Know
Pholiota microspora is a small, amber-brown mushroom with a slightly gelatinous coating that is used as an ingredient in miso soup and nabemono. It produces cluster mushrooms in small-cap and large quantities.
Pholiota microspora is the most cultivated mushroom by volume in Japan, for a reason. It is considered a valuable medicinal mushroom with cancer-fighting properties, and the traditional recipe for Miso soup is generously filled with chopped pieces. This tasty, nutty mushroom has a slippery cap, so most recipes call for incorporating the saute back into a sauce or soup so the texture is incorporated perfectly.
In some countries, this mushroom is available in kit form and can be grown at home. It is one of Japan's most popular cultivated mushrooms, tastes slightly nutty, and is often used in stir-fries. They are also sold dried.
Other names: Pholiota nameko, Nameko (ナメコ), Butterscotch Mushroom.
Pholiota microspora Mushroom Identification
Cap
The cap is orange-brown puce with the early shape of hemisphere when grows up its center sink and look flat. The cap has a smooth surface with mucilage and without squama, and a diameter of 5-8.6 cm.
Gills
The gill grows vertically and densely, white or yellow in early time, and turn to rust or ochre color when mature, at the same time the context change from weak yellow to brown.
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Stem
The stem is 5 to 7 cm long. Its yellow annulus occurs at the upside of the stipe.
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Habitat
Grows on rotten wood, crowded groups, and bunches in conditions of high humidity (90-95%). The homeland of the species is Japan and China.
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Spore Print
Dull brown.
Pholiota microspora Health Benefits
Anti-oxidant
Both in-vitro and in-vivo tests confirm that polysaccharides extracted from nameko act as antioxidants. However, these tests did not evaluate the extracts as treatments for any disease. Another study looked at a polysaccharide from nameko as a treatment for obesity in rats. The animals used in the experiment did lose weight and showed several signs of increased health in blood tests, including increases in anti-oxidant enzymes. Chemical analysis also suggests that some nameko polysaccharides could be used in cosmetics based on their anti-oxidant and moisturizing properties.
Anti-inflammatory
Nameko polysaccharides also have a recognized anti-inflammatory effect, and have been shown to reduce swelling in the paws and ears of experimentally injured mice, without causing gastrointestinal problems in rats. Whether the mice were evaluated for gastrointestinal problems, and whether the rats had swelling that the polysaccharides were able to reduce, seems unclear, based on published reports. A separate study showed that beta-glucan derived from nameko reduced inflammation-related pain in experimentally injured mice.
Inflammation plays a role in many serious health problems, so finding safe, effective anti-inflammatory treatments is important, but nameko products appear not to have been clinically tested in human beings for this property.
Other Benefits
A preliminary study demonstrated that substances useful in preventing osteoporosis can be extracted from substrate previously used to grow nameko (or any of several other wood-digesting species). These substances are byproducts of fungal digestion of wood, suggesting that waste matter left over from mushroom cultivation could be used in pharmaceutical production.
Proteins isolated from nameko inhibited the growth of human breast cancer cells, among other potentially beneficial effects. However, this was an in-vitro study, not a clinical test involving patients.
Pholiota microspora Cultivation
Substrates for Fruiting
The supplemented sawdust is recommended. Arita recommends that no more than 10% rice bran be used as a supplement for oak hardwood formulations. Some have found that 20% rice bran supports a more massive first flush and second flush when using Alnus rubra (ren alder). Arita also found that the addition of 15% rice bran was the optimum if using conifer sawdust ( Pinus densiflora - Asian Pine and Cryptomeria japonica - Japanese Cedar as the base substrate.) This is one of the few gourmet mushrooms that will give rise to substantial fruitings on conifer wood.
Yield Potentials
Fruitings, on first flush, give an average of slightly more than 1 lb. of mushrooms from a 5 lb. block of hardwood sawdust supplemented with rice bran.
Spawn Run
Incubation Temperature: 75-85* F (24-29* C)
Relative Humidity: 95-100%
Duration: 2 weeks
CO2: >5000 ppm
Fresh Air Exchanges: 0-1
Light Requirements: n/a
Primordia Formation
Initiation Temperature: 50-6-* F (10-15.6* C)
Relative Humidity: 98-100%
Duration: 7-10 days
CO2: 500-1000 ppm
Fresh Air Exchanges: 4-8 per hour
Light Requirements: 500-1000 lux
Fruitbody Development
Temperature: 55-65* F (13-18* C)
Relative Humidity: 90-95%
Duration: 5-8 days
CO2: 800-1200 ppm
Fresh Air Exchanges: 4-8 per hour
Light Requirements: 500-1000 lux.
Cropping Cylce
Two crops in 60 days, 10-14 days apart.
Notes
This mushroom is more sensitive to moisture and carbon dioxide levels than most. For indoor cultivation, a precise initiation strategy is called for. It is preferred not to use a casing layer as it promotes contamination, makes cleaning of the mushrooms tedious, and is unnecessary with good environmental controls in the growing room.
Should a casing layer not be applied, the block of supplemented sawdust must be exposed to a "condensing-fog" environment during the primordia formation period. If the aerial mycelium suddenly dehydrates, and dies back, surface primordia will be prevented and no crops will form. In this event, the cultivator mush either roughen the surface of the block and/or apply a moist casing layer, two second-choice alternatives.
To initiate mushroom formation, temperatures are lowered to the 50-60* F (10-15* C) range, carbon dioxide levels are lowered, relative humidity is increased to 98-100% rH, light levels are increased to >500 lux, and the surface mycelium is frequently misted with a fine spray of water. Approximately a week after initiating, orange streaks of slime form across the exposed surface of the mycelium. The cultivator must encourage the formation of this marmalade-looking goop. Soon thereafter, populations of primordia form and emerge within this overlaying, glutinous mass. So elastic is this material that it can be stretched more than 6 inches with each pull. This glutinous layer acts as a moisture bank promoting mushroom formation and development. Should this layer collapse due to dehydration. The primordia are at risk of aborting.
Rather than removing the entire polypropylene bag, it is recommended that most cultivators cut off the top portion of the incubation bag, leaving 3-4 inch side walls of plastic surrounding the exposed, upper surface of the sensitive mushroom mycelium. These plastic walls will help collect moisture, enhancing primordia formation. If done properly, the mushroom stems will elongate to exactly the height of these walls, facilitating harvest.
Using this casing-less approach, the second flush will be poor unless the surface is roughened to expose viable mycelium. A paddle with extruding nails or a wire brush serves this purpose well. Once the surface layer is torn apart, humidity is again raised to achieve the condensing-fog atmosphere. Soon thereafter (4-7 days), the mycelium becomes aerial, fuzzy, regenerates the orange slime layer, giving rise to another break of mushrooms. To achieve the third flush, its is recommended to turn the block upside down, roughening its surface, and following a similar strategy to that described above. Fourth and fifth flushes are usually not substantial.
The advantages of not using a casing layer are: less work; less risk of green mold (Trichoderma) contamination; and the harvested mushrooms are free of debris. Because of the glutinous nature of the P. nameko fruit bodies, casing debris readily adheres to, and is difficult to remove from the harvested mushrooms and your fingers.
Pholiota microspora Synonyms
Pholiota nameko (T. Ito) S. Ito & S. Imai, 1933
Collybia nameko T. Ito, 1929
Kuehneromyces nameko (T. Ito) S. Ito, 1959
Agaricus microsporus Berk. (1850)
Pholiota glutinosa Kawam. (1954)
Sources:
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