King Oyster Liquid Culture

Description

King oyster, also sold as king trumpet, does not look like other oysters. It grows thick, dense white stems, 2 to 5 cm wide and up to 15 cm tall, with small light tan to brown caps. The cream-white gills run down from the cap onto the top of the stem. The mushrooms grow as separate stems or small groups, not shelf-like clusters. In the wild, it grows from the roots of plants in the carrot family, and indoors it grows on sawdust.

This syringe holds living king oyster mycelium in sterile nutrient broth. It is one isolated culture, so every jar grows the same strain. The mycelium is already growing, so it starts colonizing sterilized grain within days, faster and more predictably than spores, which have to sprout first.

Flavor and kitchen uses

Raw king oyster is mild. Cooked, it turns savory and rich, and the stem stays firm and meaty. Most of the eating is in the stem.

• Slice stems into thick rounds, score a crosshatch on top, and sear them in butter like scallops.
• Shred stems lengthwise with a fork and sear the strands for tacos or sandwiches.
• Cut stems in half lengthwise and grill or roast them.
• Slice thin and add to stir-fries, ramen, and hot pot, where it keeps its bite.

King oysters keep 1 to 2 weeks in a paper bag in the fridge, longer than any other oyster.

Growing profile

Biological efficiency is fresh mushroom weight divided by dry substrate weight. At 100%, one pound of dry sawdust mix gives one pound of fresh mushrooms.

Tips for success

• Let the syringe reach room temperature, then shake it for a few seconds before each use. Shaking breaks up the mycelium so each jar gets an even dose.
• Inject the culture straight into sterilized grain, not into straw or sawdust. Use 1 to 3 ml per quart jar of sterilized rye, millet, or oats, or 2.5 to 5 ml per grain bag, so one syringe covers 3 to 10 jars.
• Wipe each injection port with the alcohol pad before you inject. The needle comes sterile. If you set it down or come back to the syringe later, flame the needle until it glows red and let it cool first.
• Check the broth before you inject. A clean culture has clear broth with white to cream wisps or clumps of mycelium that settle when it stands. Broth that stays hazy after it settles, a slimy film, green or black growth, or a sour smell means contamination. Do not use it, and send us photos.
• You do not need agar. To confirm the culture is clean before a big run, put a drop on an agar plate and look for even white growth with no colored spots after 3 to 5 days.
• King oyster needs supplemented sawdust, and supplemented sawdust needs full sterilization in a pressure cooker or autoclave. Pasteurizing is not enough.
• Let the block sit for about a week after it turns fully white before you start fruiting.
• Fruit from the top of the bag. Cut the bag open above the block and fold it down as the stems grow, so the bag walls hold some carbon dioxide around the pins.
• Thin the pins to the 3 to 6 strongest when they are thumb-sized. Fewer stems grow thicker.
• Mist the air and the bag walls, not the caps. Water sitting on caps causes brown, slimy spots.
• Harvest when the caps flatten and before the edges turn up.
• Expect uniform results. This is one isolated strain, so jars and blocks should match in stem shape, cap color, and speed.

Kit includes

• One 10 ml luer-lock syringe of king oyster liquid culture, living mycelium in sterile nutrient broth.
• One sterile 1.5 inch needle in a sealed package.
• One alcohol prep pad.

Storage

Keep the syringe in the fridge at 2 to 8 °C (36 to 46 °F), in its bag and away from light. Do not freeze it, because ice kills the mycelium. Use it within 3 months of delivery, and let it warm to room temperature and shake it before each use.