When growing mushroom, culture media are usually medium solid and consist of a water base to which nutrients are added, and a compound with solidifying properties, which is normally Agar.
The compound is mixed in the liquid phase, bringing the water in which the nutrients and Agar powder are dissolved to a boil. The liquid is sterilized and then poured into Petri dishes where it will cool and solidify to obtain a gelatinous consistency where it is possible to inoculate the mycelium to start the culture.
The culture medium must absolutely be sterile from the inoculation, and kept in conditions that prevent its contamination by agents external to the cultivation, such as molds and yeasts that are naturally found in the air.
Both unicellular organisms such as yeasts and multicellular organisms such as fungi and molds belong to the kingdom of fungi. These filamentous cells make up the reticulum that takes the name of mycelium, and these cells allow the fungus to establish unique relationships with the surrounding environment.
HOW TO START MYCELIUM CULTURE ON PETRI PLATE
There are mainly 3 methods to start growing mycelium on a Petri dish using an Agar based substrate.
- The substrate can be inoculated directly by scraping a spore print onto the Petri dish using a flame sterilized inoculation loop.
- The second method is to place a single drop from a well-shaken, flame-sterilized spore syringe in the middle of an agar plate.
- The third way is to cut with a flame sterilized scalpel a small internal portion of the mushroom that we want to clone normally taken from the stem just under the cap of the mushroom. Replacing this portion of mushroom from it, a new mycelium will begin to develop with the same characteristics of the mushroom from which we will have taken the portion.
Try to not hold a Petri dish open longer than necessary. The longer the dish is open, the greater the exposure to contamination.
Here are some of the most common culture media recipes used in mycology to grow mycelium on a Petri dish:
PDA medium with potato extract
200g of potatoes cut into slices, cleaned and peeled. They are boiled in 1 liter of water for 30 minutes. It is left to decant and filtered with a sieve obtaining just under 1 liter of aqueous potato extract to which to add:
water until it reaches 1 liter
PDYA medium with yeast and potato extract
4g potato extract (alternatively same procedure as above)
4g yeast extract
1 liter of water
MEA medium with malt extract
20g malt extract
1 liter of water
Moser medium for forest mushrooms