Dec '25 • General discussion
Initial sterilization
Step-by-Step Sterilization Protocol for Plant Tissue Culture
Sterilization is critical in plant tissue culture to eliminate microbes (bacteria, fungi) from explants, media, tools, and the work environment. Contamination is the #1 cause of failure. Protocols vary by plant species and explant type (e.g., leaves, nodes, shoots)—always test and optimize for your material.
1. Sterilize Culture Media and Vessels
Media and containers must be free of contaminants before use.
- Prepare MS (Murashige & Skoog) or other media, adjust pH to 5.7, add agar if solid.
- Dispense into vessels (jars, tubes, Petri dishes).
- Loosely cap and autoclave at 121°C, 15 psi for 15–20 minutes. 12 “Autoclave setup for sterilizing tissue culture media and vessels.” “LARGE” 11 “Home-adapted pressure cooker sterilizing media for tissue culture.” “LARGE”
- Home alternative: Use a pressure cooker (must reach 15 psi) for 20–30 minutes.
- Allow to cool before use. Heat-labile components (e.g., some hormones) add via filter sterilization post-autoclave.
2. Prepare and Sterilize the Work Area
All transfers happen in a sterile zone.
- Wipe laminar flow hood or still air box with 70–95% ethanol. 6 “Cleaned laminar flow hood ready for aseptic tissue culture work.” “LARGE” 8 “Aseptic technique inside a laminar flow cabinet.” “LARGE”
- Turn on UV light (if available) for 15–30 minutes beforehand, then airflow for 10–15 minutes.
- Spray tools, gloves, and surfaces with ethanol.
- Work quickly, minimize talking/movement to avoid airborne contaminants.
3. Sterilize Tools (Forceps, Scalpels)
- Autoclave wrapped tools beforehand.
- During work: Flame-sterilize by dipping in 95% ethanol and burning off in a Bunsen burner or alcohol lamp—heat until red-hot, cool briefly in air. 14 “Flame-sterilizing a scalpel using an alcohol lamp for aseptic transfers.” “LARGE” 16 “Forceps being flame-sterilized during tissue culture procedure.” “LARGE”
- Repeat between each cut/transfer.
4. Surface Sterilization of Explants (Most Variable Step)
Standard protocol for many plants (e.g., nodes, shoots, leaves). Adjust time/concentration to avoid killing tissue—younger material is more sensitive. 0 “Illustrated steps for explant surface sterilization process.” “LARGE” 2 “Detailed diagram of common explant sterilization techniques.” “LARGE” 4 “Overall plant tissue culture procedure including sterilization steps.” “LARGE” 1 “Scientific diagram showing surface sterilization method for explants.” “LARGE”
- Collect healthy, young explants (e.g., shoot tips, nodes).
- Wash under running tap water 10–30 minutes + a few drops of detergent (e.g., Tween 20 or dish soap) to remove dirt.
- (Optional) Brief rinse in 70% ethanol (30–60 seconds) — kills surface microbes quickly but can damage tissue if too long.
- Immerse in disinfectant: Most common: 10–20% household bleach (≈0.5–1% sodium hypochlorite) + 1–2 drops Tween 20. Agitate 5–20 minutes (shorter for delicate tissues). Alternatives: 1–5% calcium hypochlorite, or (rare/toxic) 0.1% mercuric chloride.
- In hood: Decant disinfectant, rinse 3–5 times with sterile distilled water (swirl 1–2 minutes each).
- Trim damaged/browned edges if needed—now ready for inoculation.
Tips:
- Add a drop of wetting agent (Tween) to solutions for better penetration.
- For woody/hairy plants: Longer bleach time or pre-soak.
- Monitor: Too mild = contamination; too harsh = dead explants.
- Home setups: Use fresh bleach; sterile water from boiled/cooled or distilled.
5. Inoculation and Incubation
- In sterile hood: Place sterilized explant on cooled media.
- Seal vessels (Parafilm or caps).
- Incubate at 25°C, 16-hour light.
Success comes with practice—expect some initial contamination and refine your protocol. For cannabis or specific plants, search tailored methods, as surface microbes vary. Always prioritize safety with chemicals!
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Initial sterilization
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