Sterilized Grain Bags: How to Inoculate

You may have purchased some of our sterilized grain bags we offer, or made some yourself, and now maybe wondering the best means of inoculating sterilized grain so that you can easily grow mushrooms.

We recommend using a spore syringe or liquid culture syringe, but there are many ways to do so and the best method is always dependent on your situation, the scale you operate on and the equipment you have accessible.

Here is a quick description of how to inoculate our bags using two different methods:

How to Inoculate Sterilized Grain Bags With a Syringe

Be it a liquid culture syringe or a spore syringe, all you need to do is wipe the injection port with an alcohol wipe and quickly but carefully inject the sterile needle into the injection port that comes built into our sterilized grain spawn bags. While it is best practices to do this in a clean room or a Still Air Box; it will work far more often than not in a room, a dusty garage, or anywhere else. This is only true for this method. The moment you cut open the bag to add an agar wedge or grain to grain, you absolutely need a Still Air Box at a minimum, or a Laminar Flow Hood.

if you are reusing the syringe, quick and gentle flame sterilization can be helpful but be warned: shoving a glowing red hot needle into the bag will likely damage the self-healing properties of the injection port.

Another thing that can be harmful to the injection port is aggressively moving the needle in multiple directions. Just inject it, squirt it, and pull back. You can always tumble and mix the sterilized grain bag once it has been inoculated.

How to Inoculate With Agar Wedge or Grain to Grain (G2G) Transfer.

In a very clean area, such as a Still Air Box, or in front of a large laminar flowhood, prepare your area by wiping everything down with a disinfecting or sanitizing cloth. This includes the the bag, your hands that are gloved, and the impulse sealer. The impulse sealer is an absolute must; you cannot effectively close the sterilized grain bags otherwise and expect them to be fully protected from mold spores that are suspended in the regular air.

Carefully cut open the bag by a sterile razor or other cutting instrument; we like to use a sliding paper cutter similar to this one as it provides a clean straight cut as close to the top of the bag as desired.

Separate the bag so that it is open, be careful never to put your fingers or any other device inside the sterile grain bag: it isn’t needed and will only increase your risk of contamination. Carefully and cleanly drop your colonized grain spawn or agar wedge into the opening of the sterilized grain bag and then close it, then seal it with the impulse sealer. Working fast but not clumsy is helpful, but if you ensure that you have good sterile technique and a proper clean setup you don’t need to act too fast.