The simplest of the method for mushroom grow kit is growing mycelium of mushrooms on grains of rye or something like that. To do this the grain of rye need to be placed in a flask or other hermetically sealed or almost hermetically sealed container, poured (better distilled) water, all this is sterilized, and then at normal room temperature “infected” with fungi. It can be a spore or a piece of mycelium from another similar bulb; disputes are better. “Infection”, of course, is done in the most sterile way. The mycelium begins to grow on the substrate, and after two or three or four weeks covers it from above.
Sterility: This is much easier to achieve in a biological, medical or perhaps chemical laboratory than at home. In the laboratory this is trivial: clean dishes, autoclave, distilled water, burners, etc. At home, in fact, this is also achievable. A flask with a substrate can be put in a saucepan (gauze, say) and boiled for at least half an hour. All operations should be carried out on a cleanly washed and rubbed alcohol table, the tools should also be rubbed with alcohol and calcined over the fire and, finally, all operations with an open bulb should be conducted over the fire. The complete sterility, which is necessary initially, eventually becomes not so obligatory, because the mycelium, which has developed well, will not itself grow into any infection.
Infected flasks must be thrown away!!! Or in any case, wash and sterilize again. Infection is perfectly visible both in appearance and in smell. The mycelium smells weak, and if it smells, it is quite like mushrooms brought from the forest. Its color is white; where it directly contacts the water (which is not desirable), it becomes yellowish, and on the cut (breakage) of the solid mass it, like many forest mushrooms, turns green. All other colors and shades are a clear sign of infection.
Oxygen for breathing – it’s needed by mushrooms, like us, but in much smaller quantities. Therefore, if the substrate in the flask is not very large, it may well be sealed, for the time of air development, there will be enough fungi. If not, the lid can have a hole, and on top the lid can be covered with aluminum foil (also requiring sterilization!) This gives oxygen, completely preventing the access of bacteria and mold spores.