The King Oyster (Pleurotus eryngii) is a very popular edible mushroom in many countries due to its taste, nutritional richness and commercial potential. This mushroom just like many other mushrooms provides us with a great amount of vitamins and minerals among other nutrients. Oyster mushrooms are grown on many different substrates including agricultural wastes and industrial by-products. Mushroom cultivation is believed to be one of the most efficient and economically viable bio-technology. Their ability to grow in a wide range of temperatures makes them successful candidates for cultivation.
Researchers from Iran tried cultivating these edible mushrooms on different agricultural and lignocellulosic wastes like wheat straw and wood chips in order to obtain maximum yield and nutritional values. The substrates used were wheat straw, sawdust, sugar beet pulp, barley straw, maize stem and wood chips. All these six substrates were pasteurized by being soaked overnight followed by tissue softening at 212 F (100 ºC) for 1,5 h and finally drained. Substrates were supplemented with nitrogen sources. In general, studies claim that substrates supplemented with organic/inorganic substances often boost the production. Wood chips substrate supplemented with wheat bran showed an increased production. On the other hand, the low mushroom production gap on wheat straw could be blamed on the inability of Pleurotus eryngii to produce hydrolyzing enzymes for conversion to amino acids, nitrogen, and carbon.
This particular type of mushroom is successfully cultivated on many agro-industrial wastes. Some people use rice bran, wheat bran, poultry manure, brewers grain and cotton seed meal as organic supplements. In this case, the highest biological efficiency 73% was obtained with 20% dried brewers grain. An experiment from 2000 claimed to have achieved high yield when increasing supplementation of substrate with rice bran. 2007 was the year that brought different values in terms of biological efficiency, more precisely 73% when using mixtures of wheat straw – cotton straw, wheat straw and millet straw supplemented with 15% rice bran. The highest yield 23,3g/100g and 77,2% biological efficiency was obtained by using a blending of wheat straw and cotton straw with 20% rice bran supplement.
In Egypt, scientists used four different substrate growing media: sawdust, soybean straw, sugarcane bagasse and rice straw. Each medium substrate was then mixed with 5% calcium carbonate and wheat bran. The moisture content was adjusted to 69-71%. The mixture packed in bags was autoclaved at 121 ºC for 1h. The temperature of incubation was set at 25-27 ºC. At the end of incubation, the temperature was switched to 20 ºC. Out of all substrates tested, sawdust differed and recorded the shortest incubation period. On the opposite side, sugarcane bagasse recorded the longest incubation period with the peak being of 41 days. The yield ranged from 139-196, 145-192, 150-201 g/kg depending on the media substrate. Sawdust had the highest yield, 201 g/kg and sugar cane bagasse and rice straw recorded the lowest values. In terms of biological efficiency, sawdust took the first place with 65.22%, while sugarcane bagasse had the lowest value, 45.71%.
Comparatively, in 2008 a report registered highest yield values of 28g/100g on wheat straw – soybean straw (1:1). A similar work found the highest yield to be 25.6 g/kg on wheat straw – millet straw (1:1) + 10% rice bran and a biological efficiency of 85.2%. News in 2008 reported 23.2 g/kg yield and 77.2% biological efficiency in a mixture of wheat straw – cotton straw supplemented with 20% rice bran.
Another project was conducted in Iran highlighting two different substrates, sawdust and rice straw. Different strain of king oyster (Pleurotus eryngii) respond differently depending on the substrate used for cultivation, supplements and environmental factors. The temperature required for maximum prolificity and growth is between 12-17 ºC. Sterilization is called for 1h at 121 ºC under 1kg/cm2 pressure. Results concluded that on sawdust the highest yield was seen at strain Pe-1 (141 g), closely followed by strain Pe-2 (120.25 g). By comparison, for every strain cultivated on rice straw the values were lower than those cultivated on sawdust. Highest biological efficiency was met in the Pe-1 strain (73.5%), followed by Pe-2 (62.6%) on sawdust. Just like in the case of yield performance, biological efficiency in rice straw was lower than in sawdust.
In the end, the conclusion could be that differences of growth, yield performance and biological efficiency are due to the unique biological structure of every substrate and the physiology of each strain of Pleurotus eryngii that’s matching the right strain with your local climate conditions, the formulation of a good substrate recipe and a healthy methodology remain some of the most important factors that influence overall yield for this highly prized oyster mushroom type.
A report by Malina Puia
- R. H. Hassan, et al., “Cultvation of King Oyster Mushroom (Pleurotuseryngii) in Egypt”, 2010
- K. Jeznabadi, et al., “King oyster mushroom production using various sources of agricultural wastes in Iran”, 2016
- Moonmoon, et al., “Cultivation of different strains of king oyster mushroom(Pleurotuseryngii) on saw dust and rice straw in Bangladesh”, 2010