Mushroom are non-green fungal plants that comes up seasonally in many parts of the world in various natural habitats. There are more than 2000 species of which only a few are edible and have been brought under cultivation on commercial scale. Of these, 20 species are cultivated commercially and 5 are produced on industrial scale in the many parts of the world. The species grown more commonly and having good export potential are, Agaricus bisporus (white button mushroom), Volvariella spp. (Paddy straw mushroom), Pleurotus spp. (Oyster mushroom) and Shiitake mushroom (Lentinula edodes).
In India, the major species cultivated are : A.bisporus, Pleurotus sp. and a species of recent origin Calocybe indica (Milky mushroom). The Pleurotus and Calocybe are gaining popularity in south India, because of its suitability to tropical climate. The people here are taking it up only is seasons, as a part time activity. One of the reasons for this being non availability of quality spawn on continous basis. Hence, it is thought that a briefing of spawn production can help prospective growers to take it up at their home or unit.
The word spawn means the planting material of mushrooms, which consists of the vegetative body (mycelium) and its substrate. In other words spawn could be compared to seeds of the higher plants.
Spawn production involves the following three steps.
1) Preparation of pure culture,
2) Preparation of mother spawn and
3) Multiplication of spawn.
There are two ways of preparing pure culture :: Tissue culture and Spore culture.
In Tissue culture, a well grown mushroom is selected and a small bit of mushroom from gill portion is taken using sterilized forceps and inoculated on to PDA or MEA media slants under aseptic conditions. The mycelium grows and cover the entire surface of the slant in about 7 days. This culture can now be used for further multiplication.
In Spore culture method, the spores are collected from well developed fruiting body by ‘spore mapping technique’ or ‘Spore print technique’ and then the spores thus collected are inoculated to PDA or MEA slants as in tissue culture under aseptic condition.
SUBSTRATE PREPARATION
- Select good quality substrate :: i.e. either Jowar or Wheat grains free from pests.
- Put the grains in sufficient amount of clean water and boil it for 20 – 30 minutes. When the grains become soft, remove, decant and spread the grains on a cotton cloth to drain off the excess water and cool the grains.
- Mix 20 grams of chalk powder per kg of grains to adjust the pH and avoid the grains from sticking.
- Fill 500 gms of grain to clean PP bags/covers of sufficient size (fill only upto 50% of the size of the bag) and plug the mouth of the bag tightly with non absorbent cotton.
- Sterilize the PP bags in autoclave at 15lbs pressure / sq inch (1210C for 20 minutes. After cooling to room temperature, transfer them to inoculation chamber.
- Use well grown mother spawn (18-20 days old) for inoculation.
- Stir the spawn using sterilized forceps to break the spawn to individual grains of fungal growth.
- Quickly transfer few such grains with spatula into sterilized substrate bag near the flame, under aseptic conditions and plug it with cotton.
- Shift the inoculated bags to growth room having temperature range of 25 – 30 c or to BOD if it is a small lab.
- Inspect the bags regularly and discard contaminated one immediately.
- Within 15 – 20 days of inoculation, mycelial growth covers entire substrate and the spawn is ready for use in mushroom production.
- Always use fresh spawn for mushroom production. Don’t use spawn for more than 2 – 3 generations, else the productivity will go down.
Note : take help of an expert in learning the techniques of spore printing, preparing media, maintaining aseptic environment, inoculation method and making sub cultures etc.
