Auricularia auricula and A. polytricha commonly are produced on a synthetic medium consisting of sawdust, cotton seed hulls, bran, and other cereal grains or on natural logs of broad-leaf trees (Quimio 1982; Chang and Quimio 1982; Oei 1991). For cultivation on natural logs, members of the oak family (Fagaceae) are preferred, but many other species of both hard and softwoods may be used.
For synthetic medium production of Auricularias, the substrate may be composted for up to 5 days or used directly after mixing. In either case, the mixed substrate (about 2.5 kg wet wt) is filled into heat resistant polypropylene bags and sterilized (substrate temperature 121°C) for 60 min. Composted substrate is prepared by mixing and watering ingredients [sawdust (78%) : bran (20%) : CaCO3 (1%) : sucrose (1%)] in a large pile. The pile then is covered with plastic and turned (remixed) twice at two-day intervals. For direct use of substrate, a mixture of cotton seed hulls (93%), wheat bran (5%), sucrose (1%), and CaCO3 (1%) is moistened to about 60% moisture and then filled into polypropylene bags.
After the substrate has cooled, it is inoculated with either grain or sawdust spawn. The spawn then is mixed into the substrate either mechanically or by hand, and the mycelium is allowed to colonize the substrate (spawn run). Temperatures for spawn run are maintained at about 25°C±2°C for about 28 to 30 days. Light intensity of more than 500 lux during the spawn run may result in premature formation of primordia. Temperature, light intensity and relative humidity all interact to influence the nature and quality of the basidocarps.
In Fujian, China a system has been worked out to intercrop Auricularia spp. with sugar cane. Bags containing colonized substrate are suspended in mid air on a rope stretched between rows of sugar cane. The bags then are covered with a thin layer of plastic to help regulate relative humidity. Carbon dioxide generated from the growing mycelium apparently stimulates the growth of the sugar cane (Oei 1991).
Production of most enokitake in Japan is based on synthetic substrate contained in polypropylene bottles (Fig. 1). Substrates (primarily sawdust and rice bran; 4 : 1 ratio) are mechanically mixed and filled into heat resistant bottles with a capacity of 800 to 1,000 ml. Sawdust consisting primarily of Cryptomeria japonica, Chamaecyparis obtusa or aged (9 to 12 months) Pinus spp. appears to offer the best yields. In the United States, a bran-supplemented medium, consisting primarily of corn cobs, serves as the primary medium. After filling into bottles, the substrate is sterilized (4 h at 95°C and 1 h at 120°C), mechanically inoculated and incubated at 18° to 20°C for 20 to 25 days. When the substrate is fully colonized, the original inoculum is removed mechanically from the surface of the substrate and the bottles may be placed upside down for a few days. At the time of original inoculum removal, the air temperature is lowered to 10° to 12°C for 10 to 14 days.
To further improve quality during fruiting, temperatures are lowered to 3° to 8°C until harvest. As the mushrooms begin to elongate above the lip of the bottle, a plastic collar is placed around the neck and secured with a Velcroreg. strip. This collar serves to hold the mushrooms in place so that they are long and straight. When the mushrooms are 13 to 14 cm long, the collars are removed and the mushrooms are pulled as a bunch from the substrate. The mushrooms then are vacuum packed and placed into boxes for shipment to market.
Most cultivation of G. lucidum is on supplemented sawdust contained in heat-resistant polypropylene bottles (Fig. 2) or bags. Sawdust of hardwoods is supplemented with rice bran (10%) and CaCO3 (3%), moistened with water and filled (700 g) into plastic bags. A plastic collar then is fitted onto each bag and stoppered with a cotton plug. After heat treatment (95° to 100°C for 5 h) the substrate is allowed to cool overnight and then inoculated with grain or sawdust spawn. The inoculated substrate is then incubated for 3 to 4 weeks or until the spawn has fully colonized the substrate.
Mushroom production is initiated by maintaining air temperature at about 28deg.C with relative humidity in the range of 85% to 90%. Basidiocarps begin to appear in about 1 to 2 weeks after initiation. Approximately 2 to 3 months after the appearance of primordia, mushrooms are ready to harvest. A mushroom is considered mature when the whitish margin around the edge of the basidiocarp has turned red. The substrate may yield another harvest of mushrooms after removal of the first flush.
Commercial production of most G. frondosa is on synthetic substrate contained in polypropylene bottles or bags (Fig. 3). A common substrate used for production is composed of sawdust supplemented with rice bran or wheat bran in a 5 : 1 ratio, respectively (Takama et al. 1981). For bottle production, the containers are filled with moistened substrate and sterilized or pasteurized prior to inoculation. Most growers use automated inoculation equipment thereby saving on labor costs. For production in bags, the moistened substrate (2.5 kg) is filled into microfiltered polypropylene bags and sterilized to kill unwanted competitive microorganisms. After cooling (16 to 20 h), the substrate is inoculated and the bags are heat sealed and shaken to uniformly distribute the spawn throughout the substrate. Spawn run lasts about 30 to 60 days depending on strain and substrate formulation. Temperatures then are lowered from about 22° to 14°C to induce fruiting and fruitbody maturation.
Most Maitake is marketed as food. However, Maitake has been shown to have both anti-tumor and anti-viral properties (Jong and Birmingham 1990; Jong et al. 1991; Mizuno and Zhuang 1995). Powdered fruitbodies are used in the production of many health foods such as Maitake tea, whole powder, granules, drinks, and tablets.
Polysaccharides in Hericium spp. are believed to inhibit a variety of cancers by enhancing the hosts' immune functions (Mizuno 1995b). It also has been suggested that the phenol-analogous compounds hericenone-C, -D, -E, and Y-A-8-c, which induce the synthesis of nerve growth factor, might be effective in treating patients suffering from Alzheimer's disease (Mizuno 1995b).
Bunashimeji usually is produced in polypropylene bottles contained in plastic trays. After the completion of vegetative mycelial growth, bottle lids are removed and the colonized substrate subjected to environmental conditions known to stimulate fruiting. When the mushrooms are mature, the entire cluster of fruiting bodies are removed from the bottles. The mushrooms are packaged by placing an entire cluster (or multiple clusters) into each over-wrapped package. Only one flush of mushrooms is harvested prior to mechanical removal of the "spent" substrate from the bottles. The bottles then are refilled with fresh substrate and the process is repeated.
The antitumor polysaccharide, ß-(1-3)-D-glucan, isolated from H. marmoreus showed very high activity (Ikekawa 1995). The water solubility of the polysaccharide was much higher than the same polysaccharide isolated from other fungi. Dried mushroom powder from this mushroom is believed to stimulate the radical-trapping activity of blood (Ikekawa 1995). Excessive free radicals in the blood stream are believed to hasten the aging process.
Cultivation on natural logs. Various species of trees have been used for the cultivation of shiitake (San Antonio 1981). One of the primary species used in one area of Japan in past years was the shii tree--thus the derivation of the name shii-take (Singer 1961). Most production today, however, is on various species of oak (Harris 1986; Stamets and Chilton 1982).
Natural logs usually are cut in the fall (after leaf drop) and may be inoculated within 15 to 30 days of felling. Trees that are cut in the fall also may be left intact through winter and, just before inoculation, cut into lengths of about one meter. Trees that are cut in the summer tend to have bark that is more loosely bound and sugar contents usually are lowest during this time. If trees are cut during the summer, the bark may strip off more easily, increasing the chances of contamination of the wood by competitive organisms. The most efficient log diameter appears to be in the 7- to 15-cm range (Ito 1978). Logs greater than 25 cm in diameter often are cut in half prior to inoculation (Royse et al. 1985).
Growers who inoculate the logs with wood-piece spawn drill holes in the logs with high speed drills to correspond to the diameter and length of the wood-piece spawn. Enough holes are drilled in the log to provide spacing of about one hole per 500 cm2. The wood spawn then is driven into the holes with a hammer and then usually covered with hot wax to prevent excessive drying of the spawn. Sawdust spawn sometimes is used instead of wood-piece spawn.
Spawn run may last from 6 to 9 months, depending on the tree species, log size, spawn cultivar, moisture, temperature, and other variables (Leatham 1982). After the spawn run period the logs often are transferred to a "raising" yard. Raising yards usually are cooler and more moist than the spawn run area. The change in conditions provides an optimum environment for the growth and development of mushrooms. In the raising yard, the logs are arranged to provide for convenient harvesting of the mushrooms. Most production occurs in the spring and fall when conditions are most favorable. However, prices received by the growers usually are lowest during these periods.
Growers may use greenhouses for winter production of mushrooms (Przybylowicz and Donoghue 1988). More overall production is possible, and prices for fresh mushrooms are considerably higher, in winter than during the rest of the year. In the greenhouse method, logs usually are soaked in water (usually less than 48 h) and vibrated mechanically for various periods prior to placement in the greenhouse. After the mushrooms are harvested, the logs are incubated further (up to three months) and the process is repeated (up to five times).
Synthetic log production. Sawdust (Fig. 4a) is the most popular basal ingredient used in synthetic formulations of substrate used to produce shiitake (Miller and Jong 1987). Other basal ingredients that may be used include straw and corn cobs or mixtures thereof. Regardless of the main ingredient used, starch-based supplements such as wheat bran, rice bran, millet, rye, corn, etc. are added to the mix in a 10% to 40% ratio (dry wt) to the main ingredient. These supplements serve as nutrients to provide an optimum growing medium (Royse et al. 1990).
Once the proper ratio of ingredients are selected, they are combined in a mixer and water is added to raise the moisture content of the mix to around 60%. On large farms, the mix then is augured to a machine that fills and weighs the substrate so that a uniform amount is filled into each bag (Fig. 4b). The filled bags are stacked on racks, loaded into a industrial-sized autoclave, sterilized for 2 h at 121°C, cooled and inoculated with shiitake spawn.
After a 20- to 25-day spawn run (Fig. 4c) the bags are removed and the substrate blocks are exposed to an environment conducive for browning of the exterior log surfaces. As the browning process nears completion (4 weeks), primordia begin to form about 2 mm under the surface of the log indicating that the log is ready to produce mushrooms.
Primordium maturation is stimulated by soaking the substrate in water (12°C) for 3 to 4 h. Soaking allows water rapidly to displace carbon dioxide contained in air spaces, providing enough moisture for one flush of mushrooms. Approximately 9 to 11 days after soaking, mushrooms are ready to harvest (Fig. 4d).
The main advantages of using synthetic medium over natural logs is time and efficiency. The cycle for synthetic medium cultivation lasts approximately 4 months from time of inoculation to cleanout. Biological efficiencies for this method may average from 75% to 125%. In contrast, the natural log cultivation cycle usually lasts about 6 years with maximum efficiencies around 33%. The time required on synthetic substrate, therefore, only is about 1/15th that of the natural system with about 3 times the yield efficiency. As a result of these developments, shiitake production in the United States has increased dramatically in the last nine years (Fig. 5).
Shiitake is one of the best known and best characterized mushrooms used for medicinal purposes. Several medicinal properties have been attributed to shiitake in recent years. These properties include antitumor polysaccharides activity (Breene 1990; Mizuno 1995a) and glycoproteins, antiviral nucleic acids, platelet agglutination inhibitive substances, and anti-cholesterol active substances (Tokuda et al. 1974; Fujii et al. 1978; Suzuki et al. 1979; Tokuda and Kaneda 1978; Mizuno 1995a).
At present, one company in the United States is producing morels on a commercial scale. Commercial cultivation involves the production of sclerotia, an early overwintering stage of the mushroom. "Nutrient primed" sclerotia are produced in soil placed on a layer of sterilized wheat or rye grain. The production of nutrient primed sclerotia requires about 18 to 21 days under optimum conditions. The sclerotia are harvested, soaked in clean water for 24 h and distributed into a thin layer of pasteurized bark/soil mix. The sclerotia germinate via the production of mycelium. After the mycelium has spread throughout the soil mix, a continuous (12 to 36 h) fine mist of clean water is provided to stimulate the formation of ascocarps.
Several problems have yet to be solved in the commercial production of morels. Consistent fruiting, control of competitive weed molds, poor yields, and small mushroom size are just a few of the problems facing successful cultivation. A better understanding of the many factors contributing to increased yields and quality should lower the cost of commercially produced morels to consumers.
In the United States, the primary ingredients used for Pleurotus spp. production is chopped wheat straw or cottonseed hulls or mixtures thereof. For production on wheat straw, the material is milled to a length of about 2- to 6-cm. The pH of the material is adjusted with limestone to about 7.5 or higher to provide selectivity against Trichoderma green mold (Stolzer and Grabbe 1991).
After completion of pasteurization (60°C for 1 to 2 h) the substrate is cooled and spawned with the desired strain. At time of spawning, a delayed release supplement (rates of 3% to 10% of dry substrate wt) may be added to increase yield and size of the mushroom (Royse and Schisler 1987; Royse et al. 1991; Royse and Zaki 1991). Use of supplements, however, may cause overheating of the substrate if growers are not able to anticipate and control air temperatures to maintain a steady substrate temperature.
Production of Pleurotus spp. on cotton seed hulls has some advantages over straw-based production systems in that chopping of the hulls is not required (Royse 1995). The pasteurized, supplemented hulls are spawned and filled (12 to 15 kg) into clear or black perforated polyethylene bags and then incubated at 23° to 25°C for 12 to 14 days.
In Japan, bottle production of oyster mushrooms is most common (Fig. 7). Substrate is filled into bottles, sterilized and inoculated with Pleurotus spawn. Upon completion of spawn run, bottle lids are removed and mushroom emerge from the surface of the substrate. After the mushrooms are harvested they are weighed and packaged for shipment to market.
Nameko (Fig. 8) means "viscid mushroom" in Japanese. This mushroom is prized for its gelatinous viscosity and for its flavor and is generally used in miso soup, cooked fresh with grated radish, and steamed in pipkin.
Preparation of the medium for nameko production is similar to that for enokitake except that a higher moisture content of the substrate is desirable. A substrate of broad leaf tree sawdust is preferred but research has shown that sawdusts from conifers such Pinus spp. and Cryptomeria japonica are suitable for growth. Rice bran usually is added as a supplement in the ratio of 15% for conifer sawdust and 10% for broad-leaf sawdust.
Mushrooms are harvested from the substrate by cutting the stems near the base with scissors. The harvested mushrooms are washed and packed for shipment to market.
The mixed culture technique involves the use of "helper" mycelium of Hypoxylon archeri, an ascomycete commonly associated in nature with decaying wood. Hypoxylon archeri increases the ability of T. fuciformis to digest the substrate thereby increasing mushroom yields. Exploitation of this mycelial association is accomplished through use of dual cultures to make mother spawn (Quimio et al. 1990).
Substrate used for mushroom production is the same as that used for spawn production. The supplemented substrate is packed into plastic bags (50 cm long; 9 cm diameter) and ends of the bags are tied with cotton string. Six holes (1 cm diam) then are punched in the filled bags and covered with a breathable fabric. The substrate is sterilized for 6 to 8 h, cooled and inoculated with the mother culture.
After about 30 days of vegetative mycelial growth, the hole covers are removed and the exposed substrate is exposed to conditions favorable for primordia formation (Huang 1982). If optimum conditions are maintained in the growing houses, clusters of jelly fungus should be ready for harvest within 12 to 15 days. Yield for each bag of substrate is in the range of 350 to 500 g fresh weight (35 to 50 g dry weight).
Many agricultural by-products and waste materials have been used to produce the straw mushroom. These include paddy straw, water hyacinth, oil palm bunch, oil palm pericarp waste, banana leaves and sawdust, cotton waste, and sugarcane waste (Chang 1982; Ho 1985). Volvariella is well suited for cultivation in the tropics because of its requirement for higher production temperatures. In addition, the mushroom can be grown on nonpasterized substrate--more desirable for low input agricultural practices.
In recent years, cotton wastes (discarded after sorting in textile mills) have become popular as substrates for straw mushroom production (Chang 1982). Cotton waste give higher and more stable biological efficiencies (30% to 45%), earlier fructification (four days after spawning) and harvesting (first nine days after spawning) than that obtained using straw as a substratum. Semi-industrialization of paddy straw cultivation on cotton-wastes has occurred in Hong Kong, Taiwan, and Indonesia as a result of the introduction of this method (Chang 1979).
In recent years, the trend for specialty mushroom sales has been toward the retail market (Gunn 1992; Sorenson 1992). This trend is driven partly by an increased interest in specialty mushrooms and by the convenience packaged products offer to the consumer. In some retail markets, only 10% of the customers buy 90% of the specialty types (Gunn 1992).
Some merchandisers have projected a steady growth in consumption of specialty mushrooms. As consumers become more aware of specialty mushrooms, demand is expected to increase. Aggressive marketing will help to find new markets for these relatively new products. Therefore, specialty mushroom producers seeking new outlets for their mushrooms may want to check sources listing reputable produce industry firms (Anon. 1995a, b).
Specialty mushrooms are sold fresh, dried, or processed in Japan and China. Most fresh shiitake is collected and shipped to central wholesale markets where brokers and other participants buy the mushrooms through a bidding process in Japan (Hara 1988). Mushrooms then are distributed to retailers for consumer purchase. Other mushrooms, such as Pleurotus, may be packaged at the farm and shipped directly to brokers or to retailers.
Dried shiitake is distributed through traders specializing in this mushroom (Hara 1988). These traders (about 400 in Japan in 1988; data not available for China) buy shiitake at special bidding markets and then distribute the product to retailers for in country consumption or to trading firms for overseas export. In recent years, however, exports of shiitake from Japan have declined as the number of shiitake producers have declined and shiitake production has decreased (Anon. 1992; Royse 1995). On the other hand, Chinese production of shiitake and exportation of the product to Japan have increased dramatically in the last five years.
|Scientific Name||English name||Japanese name|
|Agrocybe cylindracea (DC.: Fr.) Maire||South Popular||Yangimatusutake|
|Armillaria mellea (Vahl:Far.) Kummer||Chiodini, Honey||Naratake|
|Auricularia auricula (Hook) Underw.||Black ear, Wood ear||Kikurage|
|Auricularia polyticha (Mont.) Sacc.||Cloud ear, Tree ear, Wood ear||Angekikurage|
|Coprinus comatus (Mull.:Fr.) S.F.Gray||Shaggy ink cap, Lawyer's wig|
|Cordyceps sinensis (Berk.) Sacc.||Chinese catepillar fungus|
|Creolophus pergamenus Karsten||Bear's head||Banshariake|
|Dictyophora indusiata (Vent.:Pers.) Fisch.||Bamboo sprouts, Collared stinkhorn|
|Flammulina velutipes (Curt.:Fr) Karst.||Winter, Velvet stem, Golden, snow puff||Enokitake|
|Ganoderma lucidum (Leyss.:Fr.) Karst.||Ling-Zhi, Reishi||Reishi|
|Grifola frondosa (Dicks.:Fr.) S.F.Gray||Hen of the woods||Maitake|
|Hericium erinaceus (Bull.:Fr.) Pers.||Monkeyhead, Bear's head|
|Hypsizygus marmoreus (Peck) Bigelow||Shimeji||Bunashimeji|
|Lentinula edodes (Berk.) Pegler||Black forest, Black, Oak||Shiitake|
|Lepista nuda (Bull.:Fr.) Cook||Blewit|
|Lyophyllum decastes (Fr.:Fr.) Sing||Fried chicken||Hatakeshimeji|
|Morchella esculenta Pers. ex St. Amans||Morel|
|Naematoloma sublateritivum Karsten||Bricktop, Chestnut||Kuritake|
|Pleurotus abalonus Han et al.||Abalone||Kuroawabitake|
|Pleurotus cornucopiae (Paul.) Roll.||Golden oyster, Horn of plenty||Tamogitake|
|Pleurotus cystidiosis O.K. Miller||Ohritake|
|Pleurotus djmour (Fr.) Boedijn||Rose, Pink oyster|
|Pleurotus ostreatus (Jacq.:Fr.) Kumm||Oyster, White oyster, Gray oyster||Hiratake|
|Pleurotus pulmonarius (Fr.) Quel.||Phoenix-tail|
|Panellus serotinus (Fr.) Kuh.||Green oyster, Late fall oyster||Mukitake|
|Pholiota nameko (T.Ito) S.Ito et Imai||Viscid, Nameko||Nameko|
|Pholiota adiposa (Fr.) Quel||Fat pholiota||Numerisugtake|
|Tremella fuciformis Berk.||Snow fungus, Silver ear, White jelly||Shirokikurage|
|Tricholoma matsutake (Ito et Iman) Sing.||Pine||Matsutake|
|Tuber aestivum Vitt.||Summer truffle|
|Tuber magnatum Pico ex Vitt.||Piedmont white truffle|
|Tuber melanosporum Vitt.||Perigord black truffle|
|Volvariella diplasia (Berk & Br.) Sing.||Banana, Straw|
|Volvariella volvacea (Bull.:Fr.) Sing.||Straw, Paddy straw||Fukurotake|
|Fresh wt (x 1,000 t)|
|Production (t fresh wt)|
|Year||H. marmoreus||G. frondosa||F. velutipes||P. nameko|
Fig. 1. Production of enokitake (Flammulina velutipes) on synthetic substrate contained in polypropylene bottles; collar removed to show maturing mushrooms.
Fig. 2. Production of reishi (Ganoderma lucidum) in bottles.
Fig. 3. Maitake (Grifola frondosa) fruiting on substrate contained in plastic bags.
Fig. 4. Shiitake production on synthetic substrate: a) loading sawdust for use as an ingredient,
b) filling polypropylene bags with nutrient supplemented sawdust,
c) spawn run in plastic bags, and
d) shiitake fruiting from synthetic logs.
Fig. 5. Shiitake and Pleurotus spp. production in the United States from 1987-1994.
|Fig. 6. Morchella esculenta (morel) fruiting in the wild.|
Fig. 7. Pleurotus spp. production from polypropylene bottles.
Fig. 8. Nameko (Pholiota nameko) production on substrate contained in polypropylene bottles.