Agar or agar-agar is a gelatinous substance derived from a polysaccharide that accumulates in the cell walls of agarophyte red algae.
It is used by vegetarians and the Asian cuisine as a substitute for gelatine.
Chemically, agar is a polymer made up of subunits of the sugar galactose. It is mostly used in in microbiology for the growth of bacteria and fungi.
Mycologists (people that study the growth of fungi) grow fungi on agar to isolate the mycelium with the best characteristics for transplantation to an other substrate. This gives you a fungus with more powerful genetics and so a lager yield of mushrooms.
How to make agar:
You can buy agar in any organic or vegetarian shop or online. It comes in powder and can be dissolved in water. Often it is branded as “malt extract agar”.
Measure 1 gram of agar for each dl (1 dl = 3,5 ounces) of water. Soak the agar in the water for a couple of hours. Then boil it on low heat until all the agar powder is dissolved. Then transfer it to your petri dish or any kind of dish you like, while it is still hot. Cover the dish up and let it cool. Once the agar is cooled you are ready to go.
You’ll notice the agar has hardened and has a jelly feel to it. The agar is sterile so do not touch it, otherwise you’ll get unwanted bacteria growth.
Place a piece of mushroom tissue, some spores or mycelium on the agar. Again cover everything up so nothing gets exposed to the air to avoid contaminations. Place the agar on a warm (22-28°C), dark place for a week. You’ll already notice to growth of mycelium. Now it’s time to isolate the mycelium with the right kind of characteristics.
On the left you see a perfect example of what mycelium should look like. You can see that it started in the center from some mushroom tissue and then spread throughout the entire petri dish. You see that the mycelium is thick, white and looks a lot like bundles of threads. This is the perfect mycelium to transfer to an other substrate.
Sometimes mycelium looks a lot like a big ball of cotton. This is slow colonizing mycelium and results in a much smaller harvest.
To transfer the mycelium just cut it out. First of all sterilize a knife by using some alcohol or by holding it in a flame. Then cut out the agar along with the mycelium and just drop it on your substrate. Shake it up a little and put it in the colonization chamber.
You can even do multiple isolations of mycelium. You then just transfer from agar to agar until you get the perfect mycelial growth. Then transplant it to an other substrate and you’ll have the biggest chance of a big yield.
You can easily find petri dishes and agar on amazon: