Agar is a naturally gelatinous powder derived from marine red algae. It is used in the cultivation and study of moulds, bacteria and fungi. Although there are dozens of agar recipes for growing mushrooms, I would recommend making MEA. In order to prepare agar for mushroom cultivation purposes use the following instructions for a basic MEA (Malt Extract Agar).
Step 1: Mix 20g of agar powder and 20g of ME (Malt Extract) in 1000ml of hot water.
Step 2: Stir until dissolved then decant contents into a PC (pressure cooker) safe container.
Step 3: PC your mix for 15 minutes at 15psi, once 15 minutes are up, remove your PC from the heat and allow to cool. Do not force vent your PC, it will cause your agar to boil over inside your PC.
Step 4: Once cool enough to handle the container, in a SAB (Still Air Box) or In front of a Flow-hood pour your agar into sterile petri dishes.
Step 5: Once your petri dishes have solidified wrap with Parafilm or Micropore Tape and store in a cool, dark environment until required.
This recipe should make between 20 and 30 plates depending on how thick you pour the agar.
*Please note, this agar is not for human consumption.