Tutorials/LiquidCulture/Making and Using LC

Liquid culture (LC) is mycelium grown in sugar water. A single jar can inoculate dozens of grain jars, and because the mycelium is already alive and growing, it gets established on grain much faster than spores do.

The trade-off: contamination in liquid is hard to see. Always test your LC before trusting it with a big batch of grain.

Equipment

• Jars: pint or quart mason jars. Fill only about halfway so there's room for air.
• Lids with a self-healing injection port (silicone or a rubber stopper) for adding and drawing culture, and a gas exchange filter (a synthetic filter disc or a hole covered with micropore tape).
• Stir bar (optional but recommended): a small magnetic bar in each jar, plus a magnetic stir plate. Without one you can swirl by hand, or add a few glass marbles to help break up clumps.
• Syringes with long needles (16–18 gauge is easier to draw up thick LC).

Recipes

• ClemGrows LC: low-nutrient, crystal clear, resists blobbing
• Philly Golden Teacher LC: a bit richer, very forgiving

Most good recipes land around 2–4% sugars by weight. More is not better: high-nutrient LC grows into thick mats on the surface, turns cloudy, and caramelizes in the cooker.

Making it

1. Mix the recipe and fill jars about halfway. Drop in stir bars.
2. Cover the filters with foil so condensation doesn't soak them.
3. Pressure cook, adjusting time for altitude.
4. Let the jars cool completely before inoculating. Heat will kill your culture.

Inoculating

Working in a still air box or flow hood:

• From agar (best): cut a few small wedges from a clean plate and drop them in through a briefly opened lid, or push them through a wide port.
• From a spore syringe: inject 1–2 ml through the port. Spore-started LC can't be checked for contamination until it's grown, so testing it is especially important.
• From LC: 1 ml of good LC starts a new jar.

Wipe the port with alcohol before every needle goes in, and flame the needle until it glows red, then let it cool.

Growing it

• Keep jars at room temperature, around 70–78°F, out of direct sun.
• Stir or swirl gently once a day or every few days to break up clumps and spread the mycelium.
• Healthy LC shows white clouds, wisps, or clumps of mycelium in clear or lightly tinted liquid. Most jars are ready in 1–3 weeks.

Signs of trouble

What you see	Likely cause
The whole liquid turns uniformly cloudy, milky, or murky within days	Bacteria
A slimy film on the surface or a sour smell	Bacteria
Green, blue, black, or colored fuzz	Mold. See contamination ID
Dark amber before you ever inoculated	Overcooked. Usable, but not ideal.

Clear liquid with white mycelium is what you're after. Cloudiness that clears when the jar settles may just be stirred-up mycelium; cloudiness that stays is a red flag.

Testing

Before inoculating a big run of grain, put a drop of LC on an agar plate and on one test grain jar. If both grow clean white mycelium within a week or so, use the rest with confidence. This step catches most bad LC before it ruins a whole batch.

Using and storing it

• Shake or stir the jar first so you draw up mycelium, not just liquid.
• Typical inoculation is 1–3 ml per quart jar of grain, or 5–10 ml per grain bag.
• Store finished LC in the fridge. It keeps for several months; let it warm up and give it a stir before use.