Mushroom Spawn:
In a layman’s term it can be called as mushroom seed. Technically it is a pure culture of mushroom fungus produced under aseptic conditions in a laboratory. The thread like hypha develops from a mycelial net on inoculation in suitable media as the seeding material for culturing of mushroom.
Spawn Production:
Usually spawn is produced by raising pure culture. There are two types of pure cultures:
- Tissue Culture
- Spore Culture.
Spore Culture:
- Single Spore Culture
- Multi-Spore Culture
Tissue culture is the only method followed for commercial production of spawn. Multiplication of material by cell or tissue is known as tissue culture. This requires preparation of medium to raise pure culture of mycelium. Medium is prepared using Potato Dextrose and Agar. It is filled in culture tubes plugged with N. A. Cotton and sterilized in pressure cooker at 15 lb/sq. inch pressure and 121 degree C temperature for 20 minutes. Small pieces of mushroom culture from mother culture are placed in the medium under aseptic condition. This will be kept for 15-20 days at 25 degree C for mycelium growth which is called pure culture. Next, liquid broth medium is prepared using Potato and Dextrose. It is filled in conical flasks, plugged with N. A. Cotton, Sterilized at 15 lb pressure and 121 degree C temperature in autoclave. On cooling, small pieces of pure cultures are inoculated from the culture tubes to the PD Broth medium under aseptic condition. This is kept at 25 degree C for 10-12 days incubation when the mycelium grows in it, this gives PD Broth culture medium.
Preparation of Commercial Spawn:
Wheat grains which should not be very old or broken are cooked till – “before splitting” stage. These cooked grains are spread on polythene sheets to cool to room temperature. Calcium Sulphate powder at the rate of 5 gm. per kg. dry weight of grain and Calcium Carbonate powder at the rate of 15 gm. per kg. Dry weight of grain are mixed thoroughly and filled into double p. p. packets [200 gms each] and plugged with non-absorbent cotton. The grain filled packets are then sterilized keeping in pressure cooker at 15 lb/sq. inch pressure and 121 degree C temp. for 40 minutes. They are re-sterilized after 24 hours for 40 minutes, and then cooled to room temperature. After sterilization, the packets are inoculated with culture from the broth culture medium with @5 ml per packet and incubated at 25 degree C for about 15-20 days in which time the mycelium grows over the grains. This is called Spawn.