Mushrooms: Grain Spawn Prep

Woke up, took out the dogs, opened the chicken coop and checked on the baby chics... then strait to grain spawn prep!  Grain spawn are the "seeds" of commercial mushroom cultivation (if one were to make an analogy to plant propagation).  The main difference is that plant seeds are all genetically different, like brothers and sisters; and mushroom spawn is genetically THE SAME, like having clones of yourself.  That is because the true "seeds" of mushrooms are spores.  Spores are not used in commercial cultivation because they produce variable results in a system where consistency and reliability are key.  Thats why in mushroom cultivation you clone a certain genetic sequence - to get the consistency and reliability for making the operation more efficient and simultaneously Eco-friendly.  So, spawn is mushroom mycelium grown on grains, almost any type of grain works, some better than others. We use certified organic rye grain/berries from Azure Standard for all of our spawn.  Once grain spawn bags are fully colonized they form into a cohesive, single solid block(a single organism). After which they are broken up and shaken - to separate each piece of grain apart(hundreds or thousands of organisms, but all genetically the same).  Instead of adding a couple of large chunks of mycelium, we can add hundreds of small grain chunks increasing the surface area of the mycelium(a small group of organisms colonizes new material and reconnects to form a single organism in a new territory).



Next, Im going to give a step by step / picture by picture rundown of our grain preparation and sterilization procedures.  There are two main types of mushroom grain spawn: grain spawn masters and grain to grain (G2G) spawn.  Spawn masters are made from putting in wedges of agar from a clean culture grown in petri dishes.  G2G spawn is when spawn masters or any spawn is used to inoculate more grain spawn. Here at LGT we generally make grain spawn masters in 1L jars with specialized lids/filters.  We make large quantities of spawn via G2G transfer from our jars to larger bags.  These larger bags then go into the sawdust based substrate conducive to fungal growth.  There are so many ways to prep the grain, and make the spawn; this is just one that happens to work well for our situation.  Its quick (no overnight soak) and effective. We generally inoculate each sawdust bag with a small amount of spawn, weighing around 100g wet.  To start we put H2O into a large pot and bring it to a boil.  During this time we add some gypsum to the water to enhance mushroom growth. Both calcium and sulfur (gypsum's constituents) are minerals that greatly benefit growth.   Once boiling we add a pre-weighed amount of rye berries to the water; mix, then turn off the heat.  After 45 minutes of sitting,  we turn the heat on high for 5 minutes, mixing once or twice during this time.  We then pour it through a small strainer, give it a quick turn to get water off of the grain, then pour it into a large strainer.  Stir the grain in the large strainer for 5-10 minutes to get some steam to escape.  Then load it into either bags or jars (make sure the jars have been cleaned beforehand.)  We put the jars or bags on the scale to make sure each weighs the correct amount.  We do 350-400g per 1L jar or small spawn bag and 1.8-2.4KG per large spawn bag.  Fold the bags over and insert a tyvek sleeve into the bag opening.  Load them into the sterilizer and cook at 15+ PSI for 1.5 hours for jars and 2-3 hours for bags. Once the sterilizers are cooled down they are moved to the lab and unloaded in front of the laminar flow hood.  Between the flow hood and our filtered positive pressurization air system, the air that the sterilizers are opened in is very clean, helping to ensure success. The sterilized grain takes at least 6 hours to cool until they are ready to be inoculated.  With our setup we have left grain spawn jars or bags un-inoculated for over a month and they still were viable to use weeks later (same with agar petri dishes if kept in a sealed bag.)  This ability to inoculate whenever, helps us to stay flexible with our schedule.  You never know when your car is going to break down or your dog is going to need stitches LOL.

Keep checking back, we will have a how to inoculate grain spawn masters and grain to grain spawn bags soon!