Liquid Culture Premix Instructions: Guide for Perfect LC

Liquid Culture Premix Instructions

To prepare 1 liter of liquid culture (LC) media:

1. Measure 1 level scoop of LC premix powder (approximately 15–18 grams).
2. Add the powder to 1 liter of room temperature distilled water in a clean mixing container.
3. Stir thoroughly until the powder is fully dissolved. If available, a magnetic stir bar and stir plate are ideal for achieving a consistent mix. Otherwise, manual stirring works as well—just make sure there is no undissolved powder remaining.
4. Transfer the solution to an autoclavable vessel such as a borosilicate glass bottle or mason jar, leaving some headspace.
5. Loosely cap or cover the vessel to allow pressure equalization during sterilization. Leaving it loose is crucial for allowing proper gas exchange and avoiding accidents.
6. Sterilize the media at 15 PSI for 15–20 minutes using a pressure cooker or autoclave. Use caution during this step:
   • Always allow the pressure cooker to fully depressurize before opening.
   • Use protective gloves or mitts when handling hot equipment.
   • Never force open a pressurized vessel.
7. Cool completely to room temperature before inoculating with live culture. Introducing live culture to hot media can kill or damage the mycelium.

This formula is balanced to support clean, healthy mycelial growth while minimizing risks of caramelization and contamination. This product has been formulated by professional mycologists to have consistent results for a wide variety of species. Scale volume up or down as needed. Liquid culture premix instructions are intended as a general guideline.

Always use caution when working with hot materials and use appropriate personal protective equipment (PPE) at all times. The customer is responsible for safe use of all products. Company, manufacturers, owners, or sellers take no responsibility for misuse of this product.

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Inoculating Liquid Culture with Liquid Culture

Liquid culture can be expanded by transferring mycelium from one LC to another. This is commonly called “LC to LC.” While this method can save time and rapidly expand your culture supply, it carries a higher risk of spreading contamination if sterility isn’t maintained. Always perform LC-to-LC transfers in front of a flow hood or inside a still air box (SAB) for best results. Technically, it can be done without such equipment, but it’s strongly discouraged since any hidden contamination will be amplified in the new culture. Use sterile syringes and make only small transfers (1–2 mL) to reduce the risk of introducing contaminants.

Inoculating Liquid Culture with Agar

The most reliable way to start a new liquid culture is from a clean agar plate. Once you’ve isolated healthy mycelium on agar (free of contaminants), you can transfer it into sterile liquid culture to expand it. Using a flow hood is strongly recommended for this process, though a still air box (SAB) can also work if you don’t have one. Cut a small wedge of clean mycelium from the agar plate using a sterile scalpel, and drop it into the LC jar or vial. The mycelium will grow outward into the nutrient solution, colonizing it over time. This method ensures that your LC begins from a verified, clean source and greatly reduces the risk of contamination compared to spore syringes or LC-to-LC transfers

Inoculating Liquid Culture with a Spore Syringe

Although it is possible to inoculate liquid culture directly with spores, this method is not recommended. Spore syringes often contain bacterial or competing organisms that are invisible to the eye but will flourish in liquid culture. Instead, spores should first be germinated on agar, where healthy mycelium can be isolated away from contaminants. Only after you have a clean culture should you consider transferring it into liquid culture. If you do attempt spore-to-LC inoculation, always use a sterile workspace (flow hood or SAB) and treat the resulting culture with caution until verified on agar.

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Inoculating Agar with Liquid Culture

Transferring liquid culture to agar is one of the best ways to check its purity and ensure you’re working with clean mycelium. Place agar plates inside a flow hood or SAB, flame-sterilize your syringe needle, and apply 1–2 drops of liquid culture to the surface of the agar. The mycelium will begin to grow outward from the inoculation points, allowing you to assess its health and identify any contaminants. This step is highly recommended before scaling up to grain, as it acts as a “checkpoint” for culture quality.

Inoculating Grain with Liquid Culture

Once you’ve confirmed that your liquid culture is healthy and clean, it can be injected directly into sterilized grain bags or grain jars. For each standard 3–5 lb grain bag, use 3–5 mL of liquid culture. Larger bags can take up to 10 mL. Always flame-sterilize the syringe needle before injection. If you have a flow hood or SAB, use it — but if not, our grain bags come with self-healing injection ports that allow for a safer inoculation without open-air exposure. Simply inject the culture through the port, withdraw the needle, and mix the bag gently to distribute the liquid evenly. This ensures strong, even colonization across the grain.

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Liquid Culture Storage

Once your liquid culture is fully colonized and ready for use, it should always be stored in a refrigerator between 2–8 °C (35–46 °F). This cool, stable environment slows the mycelium’s metabolism, extending its shelf life while keeping it viable for future inoculations. Cultures should be kept in sterile, airtight, autoclavable containers and placed away from light to prevent degradation or contamination. Under these conditions, liquid culture can remain healthy and usable for 6–12 months, making proper storage just as important as the preparation process itself.

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How to Make Liquid Culture FAQ