Pleurotus spp

The fungi are a group of eukaryotic organisms. Due to their microscopic cellular dimensions, they are of great interest to microbiologists. Multicellular fungi is familiar to each and every one of us. The velvety blue and green growth on rotting oranges and lemons as well as on stale cheeses, the whitish grey furry outgrowth on bread and Jam, and the mushrooms in the field. These are the bodies of a variety of fungi. Fungi are heterotrophic organisms”They need organic compounds for nutrition.

The classification of fungi, unlike that of bacteria, is based primarily on the hracterstics of the sexual spores and fruiting bodies, present during the sexual stages of their life cycle. However, the sexual spores and fruiting bodies are produced only under certain environmental conditions, if they are known to produce them at all. Pleurotus is a genus of gilled mushrooms which includes one of the most widely eaten mushrooms. Species of pleurotus may be called oyesters, abalone or tree mushrooms and are some of the most commonly cultivated edible mushrooms in the world.

They have been very much useful in mycoremediation of pollutants such as petroleum and polycyclic aromatic ydrocarbons. The name pleurotus has been derived from the greek word pleure (side) + otos (ear) which means "Side Ear". The following are the details of Pleurotus Genus scientific classification: l. The kingdom of pleurotus is Fungi, II. Phylum is basidiomycota, Ill. class is Agaricomycetes 'V. Order is agaricales V. Family is pleurotaceae The basic structure of oyster mushroom includes a capwhich may be laterally attached (with no stem).

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If there is a stem, it is normally eccentric and the gills are extended downward along it. The term pleurotoid is used for mushrooms having this eneral shape. There are certain cylindrical spores which are smooth and elongated. Where hyphae meet, they are Joined by clamp connections. Pleurotus is not considered to be a bracket fungus and most of the species are monomitic (with a soft consistency). Pleurotus Ostreatus Specifications Scientific name: Pleurotus ostreatus Oacq. ) P. Kumm. Derivation of name: Ostre- means "oyster" and atus means "resembling. " Synonyms: Agaricus ostreatus Jacq.

Common name(s): Oyster mushroom. Phylum: Basidiomycota Order: Agaricales Family: Pleurotaceae Occurrence on wood substrate: Saprobic or parasitic; olitary to more typically in overlapping clusters on living or dead deciduous trees, on rotting logs and stumps, sometimes on conifers; April all the way through November, year-round during mild periods. Dimensions: Caps 5-20 or more cm wide; stipes 0. 5-4 cm long and 0. 5- 3. 5 cm thick. Stripes may be absent. Cap: Moist or dry; smooth; variable in color: whitish to cream, greyish to brown, some with lilac tones; oyster shell- shaped to fan-shaped or semicircular.

Gills: Decurrent or glowing from point of attachment; broad; whitish, yellowish in age. Spore print: White to pale lilac-gray. Stipe: Sometimes absent or rudimentary. If present, lateral to eccentric or even central if fruitbodies are on top of a log or stump; whitish; hairy at base. Veil: Absent. Edibility: Edible, rated as choice. The oyster and abalone mushrooms belong to the genus pleurotus. They have a high saprophyte colonizing ability and can grow on virtually any agricultural waste. They rank among the top six mushrooms produced in the world.

It should be noted that the availability of a good strain of mushrooms, suitable substrate for cultivation and control of saprophytic and parasitic microorganisms are the three most important spects for mushroom cultivation. The world production for this genus was 169,000 tons in 1986. The consumption and production of edible mushrooms in developing countries have occurred for many years. There has been a high upsurge of interest in cultivation of this mushroom in the last decade. Because of their spicy flavour and their medical effects in dropping plasma cholesterol, mushrooms are widely consumed in Europe, the U.

S. A and Japan. Many of the fleshy sporocarp species of the many acomycetes and basidiomycetes can safely be eaten while only a few poisonous species of the fleshy fungi can be found . However more than one thousand mushrooms are known, about one hundred mushrooms are edible and only a few are considered of a commercial value. Pleurotus ostreatus is relatively easy to grow. A few trials to produce the mycelium of oyster mushrooms in Egypt using some agro industrial wastes were only recently carried out. The goal of this work was to study the cultivation of oyster mushroom (Pleurotus spp. emphasizing the effect of different media and organic substrates on production. Mushrooms of Pleurotus spp. are commonly known as oyster mushrooms which occupy the second osition among cultivated edible mushrooms worldwide due to their nutritional values. They are widely cultivated all over the world. Its production is remarkably affected by the environmental conditions like temperature and relative humidity. In this study, we investigated the production of four species of oyster mushroom: 1 . ) Pleurotus ostreatus 2. ) P. florida 3. ) P. aJor-caJu and 4. ) p. High king Cultivated in every season( January to December) in Bangladesh. The temperature (in C) and relative humidity (%RH) ot culture house in each month, and parameters ot ushroom production were recorded. In all of the selective study of this species, the minimum days required for primordial initiation, and the utmost number of fruiting bodies, biological yield and biological efficiency were found during December to February (14-27 oc, 70-80% RH). The production was found minimum during the cultivated time August to October.

We suggested cultivation of selected Pleurotus spp. in winter (temperature zone 14-27 oc with relative humidity for better production and biological efficiency. The environmental factor is very important for the production of oyster mushrooms. Various mushrooms are known to be very sensitive to the climatic conditions. The major environmental factors like temperature, humidity, fresh air and compact materials affect in mushroom production. Pleurotus spp. grows in wide range of temperature (15-30 oc) which also varies from species to species.

Oyster mushrooms Pleurotus spp. draw their nutritional requirement from a host substrate or from the agricultural wastes rich in lignin, cellulose and hemicelluloses used for their cultivation. Due to varying nutrients in the substrates, different mushroom yields have been recorded by various workers. Oyster mushrooms are grown from mycelium (threadlike filaments that become interwoven) propagated on a base of steam-sterilized cereal grain (usually rye or millet). This cereal grain/mycelium mixture is called spawn and is used to seed mush-room substrate.

Most spawn is made with mycelium from a stored culture, rather than mycelium whose parent was a spore. This is because spores are likely to yield a new strain and performance would be unpredictable. Spawn-making is a rather complex task and not feasible for the ordinary mushroom grower. Spawn of various oyster mushroom species may be urchased from com-mercial spawn makers who usually provide instructions for its use. Spawn frequently is shipped from the manufacturer to growers in the same aseptic containers used for spawn production.

Inoculum for spawn production is frequently produced in polyethylene bags containing a micro porous breather strip for gas exchange. Most commercial spawn production companies produce spawn only from inoculums that has met strict quality control standards. These standards include verification of inoculums production performance before it is used to produce spawn and assurance of the spawn's biological purity and vigour So ariable in size, shape and colour are the many kinds of oyster mushroom that confident recognition of some species is tricky without resorting to microscopic analysis.

The process is not helped by the fruiting habit of many Pleurotusspecies that seem to delight in emerging beyond reach, sometimes high up in the crowns of trees. For the most part the various oyster mushrooms are saprophytic on deciduous trees, and only very rarely are they found on conifers. Distribution Pleurotus ostreatus, the Oyster Mushroom, occurs throughout Britain and Ireland as well as in most parts of mainland Europe. It is also widely distributed throughout much of Asia, including Japan, and is present in parts of North America.

Several similar species within the Pleurotus genus are often confused, and so distribution data for individual species in this complex group are inevitably subject to some uncertainty. Taxonomic history The Oyster Mushroom was first described scientifically in 1775 by Dutch naturalist Nikolaus Joseph Freinerr von Jacquin 7) and named Agaricus ostreatus. (In the early days of fungus taxonomy most of the gilled mushrooms were incorporated in the genus Agaricus. ) In 1871 German mycologist Paul Kummer transferred the

Oyster Mushroom to the genus Pleurotus (a new genus that Kummer himself had defined in 1971), giving it its currently accepted scientific name. Synonyms of Pleurotus ostreatus includeAgaricus ostreatus Jacq. , Crepidopus ostreatusoacq. ) Gray, and Pleurotus columbinus Quel. The blue-grey-capped form of this mushroom is referred to by some authorities as Pleurotus ostreatus var. columbinus (Quel) Quel. Etymology The generic name Pleurotus is Latin for 'side ear' and refers to the lateral attachment of the stem;ostreatus is a reference to oysters, and in shape the fruitbodies often do esemble oyster shells.

The specimens shown on this page show Just how changeable Oyster Mushrooms can be - not only in colour and form but also in their growing habitat. From the top: on a dead Beech trunk; next on a standing live (but surely dying) Cabbage Palm; and at last on a dead branch broken fallen from an old Ash tree. Importance of nitrogen sources for the growth of pleurotus spp. :- i) Nitrogen is an essential element for cellular functions, for growth and various metabolic activities, particularly protein and enzyme synthesis. i') The nitrogen content of mycelium ranges between 3-6%. i) Cereal straw used for cultivation of oyster mushroom is a poor source of nitrogen (0. 5 to 0. 8%) and at the time of fructification when most of the nitrogen is utilized for mycelia growth, the depleted nitrogen in the substrate becomes inadequate and limits mushroom yield. 'v) In the present studies seven dissimilar nitrogen sources : wheat bran, rice bran, soya bean floor, de-oiled soya bean meal, mustard cake, cotton seed cake and cotton seed meal were evaluated for their effect on mushroom yield. v) Cotton seed cake and de-oiled soya bean meal gave significantly higher yield than unsupplemented bags.

Review of literature : The oyster mushroom Pleurotus spp is a saprophytic fungus commercially cultivated throughout the world because of its tasty basidiocarp and simple cultivation technology. It is also one of the choicest white rot fungi for research scientists to investigate. Pleurotus spp's lignocellulolytic enzymes for bioremediation (Arisoy and Kalan Kayan 1997, Walter et. al. 1997), its flavour compounds, (Mau et. al. 1998), its synthesis of diterpene and polysaccharide (Gutirrez et. al. 1996) and its natural pigment extraction (Shirata and Kato 1998) make it a promising subject for study.

Oyster mushrooms are mainly cultivated on residues from agricultural crops such as wheat, paddy, cotton, sugar cane or soybean (Sohi and Upadhyay 1989, Savalgi and Savalgi 1994). Pleurotus spp also have the potential to mineralize and grow on industrial wastes such as tea (Upadhyay et. al. 1996), apple pomace (Upadhyay and Sohi 1988) or non-conventional substrates containing lignin, cellulose or hemicellulose such as dried Populus leaves. (Upadhyay and Verma 2000). These residues are low (0. 5 to 0. 8%) in nitrogen content. Several workers have reported varying fresh oyster mushroom yields using crop residues (Sohi and Upadhyay 1987,

Madan et. al. 1987). The variations may be due to the nutrient status of the substrate used for cultivation. The production of oyster mushrooms after the first flush is drastically reduced and there is a tlusn break ot 10 to 20 days depending upon the species of oyster mushroom. The yield turn down could be due to either depletion of nutrients or accumulation of toxic substances unfavourable to fruiting. In Agaricus bisporus, increased yields have been reported by supplementing with various proteins, carbohydrate or oil rich supplements like soybean meal, cotton seed meal, alfalfa meal or corn gluten meal.

Sinder and Schisler 1962, Gerrits 1983). In the present studies seven different organic nitrogenous materials were evaluated to find out their effect on yield. The best substrates were further evaluated for their optimal dose with maximum yield. Materials and Methods Prewetted chopped wheat straw (2-3cm) was mixed with calcium sulphate (4% w/w) and carbendazim 50% w. p. (1 5g/quintal) and a rectangular pile prepared. It was given two turnings on alternate days for four days so that the temperature did not exceed more than 600C during fermentation.

After four days, the partially fermented traw was pasteurized in a tunnel at 700C for 6h and subsequently conditioned at 450C for 36h. Supplements (wheat bran, rice bran, cotton seed meal, cotton seed cake, soybean meal, de-oiled soybean cake and mustard cake) were separately treated in a answer of carbendazim (100ppm) for 16h. The rate of adding up of all the supplements was 5% (dry wt. ) except wheat and rice bran (10%). Treated supplements were thoroughly mixed at the time of spawning with pasteurized straw. Twenty-day-old spawn of P. ostratuas var florida was added at a 3% wet wt.

Five kg spawned substrate was filled into 45x30cm polyethelene bags with 10 holes (5mm ia. ). Each supplement had six replications. Spawned bags were incubated in a dark cropping room (temp. 13-18'C). Colonized bags were opened after 25 days. A relative humidity of 70-75% was maintained by spraying water twice a day; 6-8h light was provided with fluorescent tubes; and carbon dioxide concentration was maintained at 700-780 ppm in the cropping room. Mushrooms were harvested daily before spraying and data were recorded. Biological efficiency (BE) was planned on the basis of fresh mushrooms from 100 kg dry substrate weight.

In the second experiment, cotton seed cake and de-oiled soybean cake were further evaluated r their effective optimum dose. The supplements were treated as before, at a rate of 1, 2. 5, 5, 7. 5 and 10% substrate dry weight. Table 1. Effect of organic supplements to wheat straw on fresh mushroom yield of Pleurotus ostreatus var florida in 60 days. S. No. Substrate + Supplements Average Yield (kg) per kg substrate Biological efficiency (BE) (%) Percent increase (+) or decrease (-) from control Wheat straw + wheat bran (10%) 0. 860 86. 0 +20. 6 Wheat straw + rice bran (10%) 0. 838 83. 8 +17. 5 3.

Wheat straw + cotton seed cake (5%) 0. 946 94. 6 -12. 2 4. Wheat straw + cotton seed meal (5%) 0. 46 64. 6 5. Wheat straw + soybean meal (5%) 0. 732 73. 2 2. 6 6. Wheat straw + de-oiled soybean cake (5%) 0. 928 92. 8 +30. 1 7. Wheat straw + mustard cake (5%) 0. 532 53. 2 -25. 3 8. Wheat straw (control) 0. 713 71 . 3 CD at 0. 21 1 Table 2. Effect of different doses of de-oiled soybean cake on fresh mushroom yield and dry matter of Pleurotus ostreatus var florida. S. NO. Rate of supplementation (Dry wt. ) % increase over control % dry matter content in 1st and 2nd tlusnes Wheat straw 1% soybean 92. +21 9. 85 10. 04 2. 2. 5% soybean 84. 8 +11. 57 9. 45 10. 0 5% soybean 84. 5 +11. 18 10. 29 10. 25 7. % soybean 87. 8 +1 5. 52 8. 8 9. 75 10. 0% soybean 83. 2 +8. 15 9. 3 10. 55 76. 0 6. 9 The dry matter content of mushrooms harvested from both the supplements at different doses are shown in Table 2 and Table 3. Soybean supplementation generally yielded heavier mushrooms in the first flush than cotton seed cake supplementation. Maximum dry matter content was recorded from bags supplemented with 5% de-oiled soybean cake and further increase in supplementation did not yield heavier mushrooms.

In cotton seed cake, the heaviest mushroom truit bodies were observed with 0% dose in the first tlusn, while in the econd flush, the lowest rate of application gave the heaviest mushrooms. The dry matter content in the second flush was generally more than the first flush for both the supplements. Interestingly the spore print colour of the mushrooms from 10% soybean was a creamy yellow. The nutritional analysis of mushrooms attain from different supplements is under investigation. The addition of cotton seed cake gave the maximum yield increase (+47. 7%) while soybean cake gave heavier mushroom fruit bodies than cotton seed cake.

The use of supplementation increased the substrate temperature (Figurel and Figure 2) from the fourth day onwards to the ixteenth day. Bags with de-oiled soybean cakes showed a rise in temperature from 3 to 90C over room temperature and 3 to 50C over unsupplemented bag temperature. Cotton seed cake addition showed less temperature rise compared with similar doses of soybean cake. The utmost rise in temperature was between the fourth day and the ninth day. Table-3: Effect of different doses of cotton seed cake on fresh mushroom yield and dry matter of Pleurotus ostreatus var florida.

Substrate used Biological Efficiency (%) % Dry matter content in 1st and 2nd flush Wheat straw + cotton seed cake 1% 90. 4 +18. 94 7. 3 10. 5 Wheat straw + cotton seed cake 2. 5% 100. 3 +31 . 97 8. 1 9. 82 Wheat straw + cotton seed cake 5. 0% 112. 0 +47. 36 7. 8 9. 49 Wheat straw + cotton seed cake 7. 5% 105. 3 8. 0 Wheat straw + cotton seed cake 10% 112. 3 +47. 7 9. 01 9. 0 9. 28 CDat5% DISCUSSION Although commercial cultivation of oyster mushroom Pleurotus spp started very late compared to Agericus bisporus (1650 A. D. ), Lentinula edodes (1100 A. D. and Auricularia spp (600 A. D. ), it occupies the third place in the world among the cultivated mushrooms. Successful cultivation of oyster mushroom using cereal straw was reported in 1962 by Bano and Srivastava from India. Still, it is not widely cultivated due to inconsistent yields. The fresh mushroom yield or biological efficiency of a species is directly related to strain, substrate nutrition and growth conditions. Sustainable oyster mushroom production can be achieved by employing cultural practices which optimize and integrate nutrient management.

Agricultural residues used for oyster mushroom farming provide most of the nutrients and vitamins for growth. Carbon is readily available from cellulose, hemicellulose and lignin from straw, but nitrogen occurs mostly in a bound form and is not available until it is enzymatically released. Various workers have also reported that Pleurotus spp have the capability to fix atmospheric nitrogen (Rangaswamy et. al. 1975, Jandaik and Rangad 1977) but this has not been proved conclusively. In the cultivation of A. isporus the addition of protein rich supplements is a common practice, which indicates that either the compost is deficient in nitrogen or the bacterial proteins present in the compost are inadequate.

Rinker (1989) found 37 and 42. 6% more total yield in P. ostreatus from supplementation with barley straw with brewer's grain and 17, 27, 65 and 118% more yield by addition of alfalfa hay at 5, 10, 20 and 40% (dry wt. basis). He also found that supplementation prior to pasteurization increased the total yield, but mushroom size was negatively affected with increased supplementation. In our studies we have not found any significant effect on mushroom size. Influence of supplementation is also species and strain-specific.

Somycel 3200 reacted poorly to alfalfa meal and negatively to chicken manure, and Somycel 3001 reacted positively to rice bran and alfalfa meal at the time of filling (Visscher 1989). Upadhyay and Vijay (1989) also observed cotton seed meal as better supplement for P. fossulatus and rice bran for P. ostreatus. Supplementation is absolutely necessary for getting fructification is some strains of P. eryngii (Royse 1999, Upadhyay and Vijay 1991). With supplementation came a rise in substrate temperature, possibly due to faster metabolic activities riggered by extra nitrogen.

Royse and Schisler (1986) also observed overheating (from 300C to 470C) in bags where Spawnmate was applied without benomyl treatment, and proposed that it could be due to the growth of competitor moulds. GurJar and Doshi (1995) did not find any effect on yield of P. cornucopiae with 5 and 7. 5% addition of soybean meal in wheat straw and assumed this could be due to a rise in temperature. We identified increases in the temperature of beds from 5 to 90C over room temperature. Therefore, supplements should be cautiously used, because excessive bed temperature (more than 350C) may kill the mycelium.

OverstiJns (1995) observed an increase of 19% in mushrooms with the addition of only 0. 5% corn steep liquor and recorded a rise in temperature from 0. 3, 1. 4 and 2. 30C with the addition of only 0. 5, 1 and 2% corn steep liquor. Higher supplement doses gave even higher temperatures, which were harmful and attracted growth of Coprinus sp (Guna segaran and Graham 1987). In A. bisporus, the addition of formaldehyde-pretreated 1 and 2% cotton seed meal and soybean meal at the time of casing produced 20 and 30% higher yields respectively, but higher doses of supplement attracted a lot of contamination (Gupta and Vijay 1992).

Supplementation has also been found to facilitate higher mushroom yield in other mushrooms such as Agrocybe aegerita and L. edodes (Zadrazil 1994, Jong 1989). Higher supplementation (3 to 4% w/w) of NPK in rice husk, melon husk and coconut fruit fibers did not give either mycelium growth or basidiocarp from the tubers of P. tuberregium (Isikhuemhen and Okhuoya 1998). Supplementation with de-oiled soybean and cotton seed cake not only gave higher biological efficiency but the fruit bodies were significantly heavier than in unsupplemented bags.

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