Lyophyllum shimeji
Description
Lyophyllum shimeji is an edible species of fungus in the family Lyophyllaceae. It is an ectomycorrhizal fungus that grows in association with Japanese red pine and/or oak trees. The mushroom is prized as the most delicious and the next most expensive mushroom to Matsutake (Tricholoma matsutake) in Japan. L. shimeji has been successfully cultivated experimentally in pure culture using the selected strains capable of growing saprobically. It is found in Japan, Sweden, Finland and Estonia.
The general name "Shimeji" has been widely used to describe some of the best Japanese gourmet mushrooms and has been assigned to about 20 mushroom species. However L. shimeji has been called "Hon-shimeji" (Hon means true in Japanese, true-Shimeji) in Japan because the fungus is the richest flavored mushroom among mushrooms with the general name Shimeji.
Lyophyllum shimeji is similar in appearance to the edible species Lyophyllum decastes and toxic species Lyophyllum loricatum, Lyophyllum connatum, Clitocybe dilatata, and those of the Entoloma genus are also similar in appearance.
Common names: Hon-Shimeji (Japanese), Daikokushimeji.
Mushroom Identification
Cap
2-8 cm across, hemispherical when young, later convex with an incurved margin, eventually plane, surface smooth, slightly lubricous, dark gray when young, later gray-brown to light gray.
Flesh
White, thick.
Gills
White to slightly cream, small depressed or slightly decurrent.
Stem
3-8 cm, white, usually ventricose when young, later cylindric.
Spores
Globose, smooth, 4-6 um.
Cultivation Tips
Available Strains
Ohta (1994a, 1998a) recommended the wild strain SF-Ls6 as having high productivity and high quality. However, this strain readily forms warty structures on the surface of the cap. Warts on the cap surface notably decrease the quality and market value of the mushroom. Yoshida & Fujimoto (1994) have used only wild strains to form fruit bodies. These wild strains in experimental cultivation were low yield and low quality for cultivation of L. shimeji commercially. Wild strains vary in their morphology and the color of the mushrooms at maturity. It is supposed that Takara Bio Inc., also uses the wild strains for commercial cultivation in sophisticated and automated facilities. Fruit bodies produced by Takara have a darker colored cap and gill compared with general wild strains of this fungus. Yamasa Corporation has produced fruit bodies commercially using new high-quality and high-yielding strains developed by mating between excellent wild strains. The fruit bodies are extremely similar morphologically to those of wild strains.
Substrate
Ohta (1994b) found that a mixture of barley grain and beech sawdust supplemented with synthetic nutrients was the best substrate to form fruit bodies in bottle culture of L. shimeji. Table 1 shows the culture conditions for the production of this fungus devised by Ohta (1998b). Yoshida & Fujimoto (1994) used a solid medium for fruit body formation, adding 750 ml of liquid medium (consisting of: soluble starch 100 g, D-glucose 25 g, pectin 1 g, yeast extract 3g, KH2PO4 0.5 g, MgS04 0.5 g, thiamine-MCl 1 mg, CaCO3 5 g, charcoal powder 5 g, water 860 ml) to 120 g of peat moss.
Barley grains are suitable material as a starch source for the substrate to produce L. shimeji fruit bodies. However, barley grain medium is immensely expensive for commercial cultivation. In addition, barley grain medium results in a non-porous condition in the substrate and retards mycelial colonization because of swelling and viscosity of barley grains after autoclaving. Therefore, Takara uses the substrate based on hardwood sawdust supplemented with corn grits and/or corn meal. At Yamasa, the basal medium for L. shimeji production is composed mainly of a hardwood/softwood sawdust mixture, corn meal and barley grain.
Substrate Mix Ingridients
Barley grain 875g (dry wt), hardwood sawdust 542g (dry wt). Moisture content of the Substrate: 70 % on a wet weight basis
Cultivation Bottles & Filling
Ohta (1998b) produced the fruit bodies using 400 ml of barley/hardwood sawdust substrate contained in 800 ml polypropylene bottles with a large opening. However, such half-filling of the substrate into the bottles is inefficient and uneconomical for commercial cultivation because bottles cannot be half-filled with substrate using automatic filling machines. Moreover, the cropping of the fruit bodies produced inside the bottle is very difficult. Takara fills the substrate into 1,100 ml bottles with the opening of 82 mm in diameter, and then mechanically drills five holes into the substrate to inoculate with liquid spawn. Yamasa uses 800 ml polypropylene bottles with an opening of 75 mm in diameter, that are filled mechanically with substrate, and that contains approximately 640 g of substrate per bottle.
Utilization of Liquid Spawn
Solid spawn produced on a sawdust substrate has been used in experimental cultivation. Takara has used liquid spawn for commercial production of L. shimeji. We also confirmed that liquid spawn inoculation resulted in faster colonization of the substrate by fungal mycelia and gave high fruit body yields of good quality in the commercial cultivation of L. shimeji.
Spawn Run
In the cultivation of L. shimej using 800 ml bottles filled with 400 ml of substrate (Ohta 1998b), the inoculated bottles are placed in an incubation room at 20-23[degrees]C and 60-70 percent relative humidity (RH) for spawn running. Forty to fifty days after inoculation, mycelia have fully colonized the substrate. According to Yoshida & Fujimoto (1994), 870 g of a substrate composed of peat moss/liquid medium contained in a polypropylene bag was incubated at 23[degrees]C and 70-80 percent RH for 90 days after inoculation. In the commercial production of L. shimei in Takara, 1,100 ml polypropylene bottles containing the substrate are initially incubated at 21[degrees]C for 40 days and then for 70 days additionally after the inoculation. In commercial cultivation at Yamasa, inoculated bottles of 800 ml size are placed in an incubation room at 23[degrees]C, 65-70 percent RH for 80-85 days.
Casing & Casing Materials
According to Ohta's cultivation manual (1998b), the surface of the substrate was covered with autoclaved peat moss as a casing material and the substrate was incubated for an additional 5-7 days after casing. The casing material, consisting of 20 liters of peat moss, 100 g of CaCO3 and 10 liters of water, was adjusted to pH 5.0-5.4 before autoclaving. However, peat moss is totally inadequate as a casing material for the commercial cultivation of L. shimeji because peat moss falls between the stipes of fruit body clusters and soils white stipes. Consumers must then wash the mushroom with water. Takara initiates the primordial formation by Kinkaki (in Japanese, raking off the surface of substrate to stimulate fruiting) without the need for casing. Yamasa uses Kanuma-soil (porous, lightweight granular soil) as the casing medium. The substrate covered with casing layer is incubated at 20-23[degrees]C for 10-14 days.
Primordium formation (Medashi in Japanese)
After Kinkaki, and additional incubation for approximately 10 to 14 days after casing, the bottles are placed in a pinning room at 15-16[degrees]C, 80-90 percent RH and 600-1,000 ppm C[O.sub.2] concentration to stimulate primordium formation (Ohta, 1998b). Illumination (500-600 lux) in the daytime is required for the induction of primordia. Primordia are formed on the surface of the substrate (Takara), or the surface of the casing layer (Yamasa), 10 to 14 days after transfer of the bottles to the pinning room controlled at 15-16[degrees]C, 95 percent RH.
Growing
After 25 to 35 days, when the primordia appear on the surface of either the substrate or the casing layer, the primordia develop into mature fruit bodies ready for harvest. The cultivation cycles from inoculation to harvest in the commercial production of L. shimeji are approximately 130 days at Takara and 90-100 days at Yamasa.
Harvesting
Crop yields using the technique of Ohta (1998b) are in the range of 53 to 69 g per 800 ml bottle containing 400 ml of barley/sawdust substrate. Fruit body yields are lower under commercial cultivation. On the other hand, it is estimated that fruit body yields of 120 to 150 g per 1,100 ml bottle with the large opening are harvested at the Takara commercial cultivation facility. At Yamasa, yields are in the range of 110 to 160 g per 800 ml bottle with the large opening. Commercial production yields of L. shimeji are considerably lower compared with yields obtained through the commercial cultivation of Flammulina velutipes and Hypsizygus marmoreus.
The prices of wild L. shimeji fruit bodies in season can range from US $110 to $200 per kilogram in the retail market. The retail price of cultivated L. shimeji fruit bodies ranges from US $30 to $80 per kilogram.
Photo sources:
Photo 1 - Author: Irene Andersson (irenea) (CC BY-SA 3.0)
Photo 2 - Author: Tatiana Bulyonkova from Novosibirsk, Russia (CC BY-SA 2.0)
Photo 3 - Author: caspar s (CC BY-SA 2.0)
Photo 4 - Author: Japonica (CC BY-SA 4.0)
Photo 5 - Author: Tatiana Bulyonkova from Novosibirsk, Russia (CC BY-SA 2.0)
