The mushroom “seed” (propagation material) is generally referred to as spawn.

Availability of spawn culture

The availability of good quality spawn is the limiting factor for mushroom cultivation in many developing countries. Customs’ bureaucracy, high shipping costs and the difficulty to keep the spawn cooled during transport, often hinders imports. It might therefore be necessary for the mushroom grower to produce his own spawn. The complete procedure of spawn production involves preparation of the medium, filling the test tubes or Petri dishes and sterilizing them, and the process of inoculating larger containers with this culture. Basically, spawn production is nothing more than putting mycelium of the desired mushroom in suitable sterilized substrates under aseptic conditions.

In practice, however, producing spawn is not that simple. Suitable strains from the required mushroom species have to be maintained under strict conditions to avoid degeneration. If this is not possible tissue culture from a fresh and healthy mushroom should be used for spawn production. In addition, the spawn production room has to be kept meticulously clean to avoid any contamination.

The starter culture

The starter culture (or mother culture) can be made from a fresh and healthy fruiting body or obtained from a spawn producer or laboratory. More agar cultures are then made from this starter culture. These serve to inoculate larger containers (like bottles) with mother spawn, which can be used to inoculate the final spawn substrate. The minimal requirements for a spawn production unit are:

•  a sterilization unit (pressure cooker, autoclave)
•  sterile environment: inoculation box or laminar airflow cabin
•  laboratory equipment like Petri dishes, test tubes, scales, alcohol, flame
•  incubation room
• The above equipment is commonly available in hospitals, research stations and universities. The raw materials include:
• ingredients for media preparation
• substrate material (grain, wooden sticks (skewers), sawdust, or even oil palm fruit fibre)
•  pure culture or fresh mushroom of the desired mushroom species strain
• spawn containers (such as bottles or plastic bags)