Mushroom Agar Recipe Calculator
Calculate agar, malt extract, and nutrient amounts for mushroom culture media based on number of plates.
What is agar culture?
Agar is a gelatin-like substance derived from seaweed that solidifies at room temperature. Mycologists pour sterilized agar media into petri dishes to grow, isolate, and store mushroom mycelium. It is the foundation of mushroom cultivation β from tissue cloning to strain isolation to long-term storage.
Standard agar media recipes:
The most common recipe is MEA (Malt Extract Agar):
Per 1 liter of water:
- Agar powder: 15β20g
- Light malt extract (LME): 20g
- Nutritional yeast (optional): 2g
Recipe variations:
| Media Type | Agar | Nutrient | Use Case |
|---|---|---|---|
| MEA (Malt Extract Agar) | 20g/L | 20g LME/L | General purpose, most species |
| PDA (Potato Dextrose Agar) | 20g/L | 200g potato + 20g dextrose/L | Standard lab media |
| MYPA (Malt Yeast Peptone Agar) | 20g/L | 20g malt + 2g yeast + 1g peptone/L | Aggressive colonizers |
| Dog Food Agar (DFA) | 20g/L | 15g blended dry dog food/L | Budget-friendly, nutrient-rich |
| Water Agar | 20g/L | None | Isolation, germination |
Petri dish volume:
A standard 100mm (4") petri dish holds approximately 20β25 mL of agar media. A 60mm (2.4") mini dish holds about 10 mL.
Formula:
Total media (mL) = Number of dishes Γ mL per dish
Agar (g) = Total media (mL) Γ 20g / 1000
Malt extract (g) = Total media (mL) Γ 20g / 1000
Worked example:
Making 20 standard petri dishes of MEA:
- Total media: 20 Γ 25 mL = 500 mL
- Agar: 500 Γ 20/1000 = 10g
- Malt extract: 500 Γ 20/1000 = 10g
- Nutritional yeast: 500 Γ 2/1000 = 1g
- Water: 500 mL (distilled or filtered)
Preparation steps:
- Measure water, add agar, malt, and yeast
- Mix well (agar won’t fully dissolve until heated)
- Cover loosely with foil
- Pressure cook at 15 PSI for 20 minutes
- Let cool to 130β140Β°F (55β60Β°C) β still pourable but not too hot
- Pour into sterile petri dishes in front of a laminar flow hood or still air box
- Let solidify with lids slightly cracked (30 minutes)
- Seal with Parafilm
Contamination prevention:
The biggest challenge is contamination from mold spores and bacteria in the air. A still air box (SAB) β a clear plastic tub with arm holes β reduces contamination to under 5% when used properly. A laminar flow hood with a HEPA filter reduces it to under 1%.
Storage: Sealed agar plates store in the refrigerator for 2β4 months. Colonized plates (with mycelium) can be stored for 6β12 months refrigerated.