Cultivation of Oyster mushrooms
Penn State has an excellent commentary on the culturing of Oyster Mushrooms titled , “Cultivating Oyster Mushrooms” and it can be found at the following link: https://extension.psu.edu/cultivation-of-oyster-mushrooms
We will provide a short summary of the Penn State paper here but we highly recommend reviewing it first hand at their web site for a more comprehensive presentation.
We wish to summarize the publication here because not only do we grow Oyster mushrooms here on a very-small scale but we also base our approach to growing Trichoderma on many of the fundamentals used for commercial Oyster mushroom farming. Almost every beginner to Oyster mushroom farming has faced the major problem of Trichoderma contamination in the Oyster mushroom grow bed because the Trichoderma fungus competes and grows in the same environment as the Oyster mushroom fungus. The Trichoderma enjoys the same environmental conditions that accommodate good Oyster growth and the two fungi compete in a common environmental setting with the Trichoderma always winning. We learned how to grow the oyster mushroom successfully and now we are using our technology to grow Trichoderma which we are using two different ways:
A) As a soil amendment for our lavender plants and in our lavender field
B) As vehicle to produce cellulose enzymes to convert cellulose to fermentable sugars in the production of cellulosic ethanol.
The Penn States paper wich we are reviewing describes in much detail the modern production techniques used by large mushroom farmers today which would be ideal for most any Trichoderma farmer producing amendment as soil additives or the enzymes for bio-fuels such as cellulosic ethanol. Our Oyster mushroom growing techniques are very similar to those described here in the Penn State review as well as the Trichoderma grow techniques that we employ. For these reasons we would like to go forward and share a summary of the publication in hopes that you go to the web site posted above and read the publication in its entirety.
What Is Spawn
On large Oyster mushroom farms “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 mushroom 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.”
For early mushroom farms commercial spawn production was maintained on various agars or cereal grains with periodic subculturing of growing mycelium to a fresh medium. This method, for the most part, was reliable, although spawn makers and researchers reported cases of culture degeneration periodically. In 1970, researchers successfully preserved and maintained stability of spawn stocks of A. bisporus stored in liquid nitrogen.
Substrate Preparation
Today, for large Oyster mushroom farmers, the primary ingredients used for growing Oyster mushrooms are chopped wheat straw (Triticum aestivum L) or cottonseed hulls (Gossypium hirsutum L) or mixtures of both. For production on wheat straw, the material is milled to a length of about 2 to 6 cm. One of the most common substrates used on modern mushroom farms is a mixture of 75 percent cottonseed hulls, 24 percent wheat straw, and 1 percent ground limestone. This mixture of cottonseed hulls and wheat straw has a higher water holding capacity than cottonseed hulls used alone.
Pasteurization On Large Mushroom Farms
Typically on large mushroom farms, the Oyster mushroom feed stock is fed into revolving mixers and water is added to the desired level, and live steam is injected into the mixer while in operation. The pasteurization process uses aerated steam at 65 degree C for 1 hour by passing the air-steam mixture through the substrate from top to bottom. After pasteurization is complete, filtered air (HEPA filter, 99.9 percent efficiency) is passed through the substrate for cooling (approximately 1.5 hours).
Spawning and spawn rate
Commercial growers have found that increasing the amount of spawn used (up to 5 percent of the wet weight of the substrate) has resulted in increased yields. They believe that yield increases may be due to several factors. First, the increased level of nutrient available in higher levels of spawn used would provide more energy for mycelial growth and development. Second, more inoculum points, available from increased spawn levels, would provide faster substrate colonization and thus, more rapid completion of the production cycle. Finally, a more rapid spawn run would reduce the time non-colonized substrate is exposed to competitors such as weed molds and bacteria.
Use of delayed-release supplements
On large mushroom farms today the common practice is at the time of spawning, a commercial delayed release supplement consisting of paraffin-coated whole soybean or formaldehyde-denatured soybean and feather meal is added at rates of 3 to 6 percent of dry substrate weight, to stimulate yield of the mushroom. Yield increases of up to 90 percent have been observed when 6 percent (dry weight) supplement is added to substrate at time of spawning Delayed-release nutrient supplements have also been shown to decrease the number of days to harvest.
Filling Plastic Bags With Substrate For Oyster Mushroom Growth
Before Oyster mushroom grow time, the pasteurized, supplemented hull/straw mixture is spawned and filled (25 to 30 pounds) into clear or black perforated polyethylene bags and then incubated at 23° to 25°C (substrate temperature) for 12 to 14 days. The mushrooms form around the edges of bag perforations and may be harvested from the substrate approximately 3 to 4 weeks after spawning depending on the amount of supplement used, and temperature of spawn run.