Mushroom Culture

Spawn and its Production

What is Spawn?

• In dictionary term “ spawn '' actually refers to the fingerlings of fish, but here spawn means the vegetative mycelial network of a mushroom developed after the germination of one or more than one fungal spore (s) grown on a convenient medium. It comprises of the mycelial network along with a supporting medium which provides nutrition to the fungus for its growth and development.

Fig. 3.1 A close view of PP bag containing grain substrate kept for incubation just after inoculation from Master Culture.
Fig. 3.2 A close view of the completely spread spawn bag after 20 days of incubation – ready for use.

SPAWN PRODUCTION OF MUSHROOMS

Raising or procurement of Pure culture of mushroom.

• As already discussed in the earlier lesson,the pure culture of a fungus can be raised either by the spore print technique or the tissue culture technique. Once pure culture of a particular mushroom is established or procured from some reliable source, the process of production of mushroom spawn involves the following steps :

1. PREPARATION OF MASTER / STOCK CULTURE:

• Preparation of master culture or mother spawn is carried out under completely sterile conditions. Pure culture raised either from tissue or spores is inoculated in a suitable substratum (wheat, sorghum or rye) which provides food to the mycelium. Ten kg. of wheat grains are boiled in 15 litres of water for 20 minutes. Water is then drained off and the grains are put over the sieve or on a wire mesh tray for 8-10 hours to dry or remove excess of water. Grains are now mixed with gypsum (calcium sulphate) and chalk powder (calcium carbonate) at the rate of 2% and 0.5%, respectively on dry weight basis. 10 Kg of dry wheat grains will require about 200g gypsum and 50g chalk powder. This will help to check the pH of the medium and also prevent sticking of grains with one another. The grains are filled into half or one litre glucose bottles or PP bags which are plugged with non- absorbent cotton and sterilized at 22 lb p.s.i pressure for 1.5-2 hours. Sterilized bottles are allowed to cool down overnight. Next day bottles are inoculated with the bits of agar medium colonized with the mycelium of pure culture. Inoculated bottles are incubated at 25± 1ºC. After 7 days of inoculation, bottles are shaken vigorously so that mycelial threads are broken and become well mixed with the grains. Two week after inoculation, the bottles are ready as stock culture for further multiplication of spawn. One bottle of stock culture or master culture or mother spawn is sufficient to multiply 30-40 grain bottles or pp bags .

2. MULTIPLICATION OF SPAWN FROM STOCK / MASTER CULTURE

• Master spawn or master culture bottles / bags are further used for inoculation of large number of other grain bags / bottles prepared by the same technique and resultant is the commercial spawn. Generally few mycelial coated grains from one master culture bottle / bag will be inoculated into 30 – 40 grain bags aseptically in front of the HEPA ( High Efficiency Particulate Air ) filters of a Laminar flow and then incubated in a room at 25 ± 1 ° C for12-15 days.The commercial spawn thus prepared is used for inoculating the compost beds as seed .