A liquid mushroom culture (LC) is a suspension of live, actively growing fungal mycelium within a nutrient-rich broth, typically a sterilized water and sugar solution. This differs significantly from a spore syringe, which contains microscopic spores that must first germinate before mycelium forms. The primary advantage of using an LC syringe is the speed of colonization, as the living mycelium bypasses the germination phase. This leads to a much higher success rate and provides a direct way to introduce established genetics to a growing substrate.
Setting Up Your Sterile Workspace
Contamination is the greatest threat to a successful inoculation, requiring a highly controlled workspace. The goal is to minimize airborne particles, which carry mold and bacteria spores that can easily outcompete the mushroom mycelium. A Still Air Box (SAB) or a Laminar Flow Hood provides the necessary sterile environment.
If using an SAB, all work must occur within its confines. Sanitize the entire workspace thoroughly beforehand by wiping down the interior and all tools with 70% isopropyl alcohol. Close all windows and doors and allow the air to settle for several minutes to minimize air movement.
Gather all necessary materials, including the LC syringe, the substrate container (such as a grain jar or bag with a self-healing injection port), and safety equipment. Tools include 70% isopropyl alcohol wipes for sterilizing the injection port and syringe exterior, and a heat source (butane torch or lighter) for needle sterilization. Before heating the needle, put on gloves, wipe them down with alcohol, and ensure the syringe exterior is clean.
Step-by-Step Inoculation Procedure
The first step is sterilizing the needle tip to eliminate contaminants. Hold the metal needle in the flame until it glows dull red, indicating that it has reached a temperature sufficient to destroy microorganisms. After heating, the needle must be allowed to cool for several seconds before use; injecting with a hot needle will instantly kill the living mycelium.
Before inserting the needle, gently shake the liquid culture syringe to break up and evenly distribute the mycelial clumps floating in the solution. This ensures a sufficient amount of live culture is injected with each dose. Insert the cooled needle through the self-healing injection port of the substrate container.
Inject the liquid culture into the substrate, typically using 1 to 3 milliliters (cc) per quart-sized jar. Injecting more risks oversaturating the grain, which encourages bacterial growth. Once injected, gently withdraw the needle and immediately cover the injection port with a fresh alcohol wipe or sterile tape to prevent air exchange.
After inoculation, immediately label the container with the mushroom strain and the date for tracking progress. Place the inoculated containers in a dark, undisturbed incubation area. Maintain the temperature between 70 and 75 degrees Fahrenheit, which encourages the rapid growth and colonization of the mycelium.
Proper Storage and Handling of Cultures
Maintaining the viability of a liquid culture syringe requires specific environmental control to slow the mycelium’s metabolism. For long-term storage, refrigeration is the standard practice to keep the living mycelium dormant. The ideal storage range is between 35 and 40 degrees Fahrenheit (2 to 4 degrees Celsius); freezing the culture must be avoided entirely, as this destroys the living cells.
When properly refrigerated, a liquid culture syringe can remain viable for several months, though it is best used within six months for optimal results. Before an inoculation session, remove the refrigerated syringe and allow it to warm up to room temperature for a few hours. This gradual warming prevents thermal shock to the mycelium, ensuring the culture is active when introduced to the substrate.
After use, secure any remaining culture by removing the needle and replacing it with a sterile cap. If the needle will be reused, thoroughly clean it by drawing a small amount of 70% isopropyl alcohol through the barrel and wiping the exterior. Store the partially used syringe in the refrigerator with the needle safely capped to preserve the remaining culture.