Small-Batch Mushroom Agar Plate Recipe

🧪 Ingredients (for ~250 mL – makes 8–12 plates)

• 5 g Light Malt Extract
• 5 g Agar-Agar Powder
• 250 mL Distilled or Filtered Water
• (Optional) 0.5 g Yeast Extract (for stronger, faster growth)
• (Optional) 1 drop of Food Coloring (for contrast and easy contamination spotting)

🔥 Step 1: Mix the Medium

1. In a heatproof measuring cup or small flask, mix water, agar, and malt extract.
2. Stir until combined.
3. Heat gently on a stove or hot plate while stirring until completely dissolved — do not let it boil over.

🫧 Step 2: Sterilize

1. Pour the liquid into a small glass jar or bottle (a half-pint mason jar works well).
2. Loosely cap the lid or cover it with foil.
3. Pressure cook at 15 psi for 30 minutes.
4. Allow it to cool naturally until about 45–50°C (warm to the touch, not hot).

🧫 Step 3: Pour the Plates

1. Wipe down your workspace and tools with 70% isopropyl alcohol.
2. Work inside a Still Air Box or near a Flow Hood if possible.
3. Carefully pour about 20 mL per sterile Petri dish (about ⅛ inch deep).
4. Replace lids immediately.
5. Let them solidify 20–30 minutes with lids slightly cracked to release condensation, then close tightly.

❄️ Step 4: Store

• Once solidified, stack the plates upside down (lid on bottom).
• Seal with plastic wrap or store in a clean ziplock bag.
• Keep refrigerated (36–40°F / 2–4°C).
• Shelf life: up to 2 months if sealed and uncontaminated.

🧬 Step 5: Inoculate

• Work sterile: flame your scalpel or syringe before each use.
• Add a drop of spore syringe, a piece of clean mycelium, or a tissue sample to the plate.
• Tape the edge of the lid with Parafilm or micropore tape.
• Incubate at 75–80°F (24–27°C) until colonized (typically 3–10 days).