Cooked Rice Substrate

Fungal Inoculant Production: PDA to Cooked Rice Substrate

1. PURPOSE

To establish a standardized method for isolating, maintaining, and mass-producing resin-inducing fungal cultures for agarwood inoculants using Potato Dextrose Agar (PDA) for laboratory control and cooked rice substrate for scalable biomass production.

2. SCOPE

This SOP applies to:

  • Laboratory technicians
  • Production staff
  • Quality control personnel
  • Training participants under supervised conditions

3. RESPONSIBILITIES

RoleResponsibility
Lab TechnicianCulture preparation & transfer
Production OfficerSubstrate preparation & incubation
QC OfficerSterility checks & documentation
Biosafety OfficerCompliance with bio-handling protocols

4. SAFETY & BIOSAFETY

  • Use PPE (gloves, mask, lab coat)
  • Work in laminar flow hood when handling PDA
  • Sterilize all tools before and after use
  • Non-GM fungal strains only
  • Dispose of contaminated cultures via autoclaving

5. MATERIALS & EQUIPMENT

Laboratory (PDA Stage)

  • PDA powder or fresh PDA medium
  • Distilled water
  • Autoclave
  • Laminar airflow cabinet
  • Petri dishes
  • Sterile scalpel or inoculation loop
  • Alcohol (70%)

Mass Production (Rice Stage)

  • White or brown rice (clean, food-grade)
  • Distilled or clean potable water
  • Autoclavable polypropylene bags or glass bottles
  • Cotton plugs or filter patches
  • Pressure cooker or autoclave

6. PROCEDURE

STAGE 1: PDA PREPARATION & CULTURE MAINTENANCE

6.1 PDA Media Preparation

  1. Dissolve 39 g PDA powder per 1 L distilled water
  2. Heat with stirring until fully dissolved
  3. Dispense into flasks
  4. Autoclave at 121 °C for 15–20 minutes
  5. Cool to ~50 °C and pour into sterile Petri dishes
  6. Allow media to solidify

6.2 Fungal Inoculation on PDA

  1. Flame-sterilize inoculation tool
  2. Transfer fungal tissue or spores to PDA plate
  3. Seal plates with parafilm
  4. Incubate at 25–28 °C
  5. Observe daily for:
    • Uniform mycelial growth
    • Absence of bacterial contamination

⏱ Incubation: 5–10 days

6.3 Culture Selection & Maintenance

  • Select plates showing:
    • Dense, healthy mycelium
    • Correct morphological characteristics
  • Subculture onto fresh PDA if needed
  • Label as Mother Culture

STAGE 2: COOKED RICE SUBSTRATE PREPARATION

6.4 Rice Preparation

  1. Wash rice until rinse water runs clear
  2. Soak rice for 30 minutes
  3. Cook rice to 70–80% doneness
    (Grains must be firm, not mushy)

6.5 Substrate Packaging

  1. Fill containers/bags to ½–⅔ volume
  2. Seal with breathable cotton plug or filter
  3. Autoclave at 121 °C for 30–45 minutes
  4. Allow to cool completely (room temperature)

STAGE 3: TRANSFER FROM PDA TO RICE

6.6 Inoculation of Rice Substrate

  1. Perform all transfers in laminar hood
  2. Cut 5–10 PDA agar plugs with active mycelium
  3. Insert plugs into rice substrate
  4. Seal containers immediately
  5. Gently shake to distribute inoculum

6.7 Incubation

  • Temperature: 25–30 °C
  • Relative Humidity: Moderate
  • Light: Dark or low light

⏱ Incubation Period: 7–14 days

STAGE 4: QUALITY CONTROL

6.8 Monitoring

  • Inspect every 48 hours for:
    • Even mycelial colonization
    • Absence of green/black bacterial molds
  • Reject contaminated units immediately

6.9 Completion Criteria

Rice substrate is considered production-ready when:

  • Fully colonized (white to light cream mycelium)
  • No foul odor
  • No discoloration or slime

7. POST-PRODUCTION OPTIONS

Colonized rice may be:

  • Used directly as solid inoculant
  • Blended with sterile water for liquid inoculant
  • Extracted for biotic metabolite infusion
  • Combined with abiotic elicitors (Barino FusaTrinity™)

8. DOCUMENTATION

  • Batch ID
  • Culture source
  • Dates of inoculation & incubation
  • QC results
  • Disposal records (if applicable)

9. STORAGE

  • Short-term: 4–10 °C (≤30 days)
  • Long-term: Maintain master strains on PDA slants