Sterilisation & Contamination Prevention in Mycology — UK Guide

Introduction — Why Sterilisation Matters in Mycology

Whether you’re preparing substrates for grow kits or handling Psilocybe cubensis spore syringes for microscopy research, contamination prevention is the single most important skill in mycology. A single lapse in sterilisation technique can destroy an entire batch — wasting time, materials, and research data.

At Mushroom Spores UK, every spore syringe and substrate is prepared using the same lab-grade sterilisation methods outlined in this guide. Understanding these techniques will help you achieve clean, reliable, and repeatable results in your own research environment.

Understanding Contamination in Mycology — Common Contaminants and How to Identify Them

Recognising contamination early is essential. The three most common mycology contaminants in UK research environments are:

Trichoderma — Green Mould

Trichoderma is the most aggressive and common mould contaminant in mycology. It appears as bright green patches on substrates and spreads rapidly if not caught early. It is highly competitive and will outgrow most mycological cultures quickly.

Penicillium — Blue Mould

Penicillium appears as blue or blue-green patches, often with a powdery texture. It is commonly introduced through airborne spores and thrives in environments with poor sterilisation or inadequate airflow control.

Bacterial Contamination — Wet Spot

Bacterial contamination — commonly called wet spot — presents as slimy, wet-looking patches on substrates, often accompanied by a sour or unpleasant odour. It typically results from incomplete sterilisation of grain bags or substrates, or contaminated water sources.

Sterilisation Basics — How to Sterilise for Mycology in the UK

Heat Sterilisation — Pressure Cooker & Autoclave

Heat sterilisation is the gold standard for eliminating bacterial endospores and fungal contamination from grain bags and substrates. Use a pressure cooker or autoclave at 15 PSI for a minimum of 90 minutes. Allow bags to cool completely to room temperature before inoculation — never work with warm substrates as they create condensation and invite contamination.

• Pressure: 15 PSI
• Duration: 90 minutes minimum
• Cooling time: 12–24 hours before inoculation

Surface Sterilisation — 70% Isopropanol

Wipe down all work surfaces, gloves, and equipment with 70% isopropanol (IPA) and allow to fully air-dry before beginning any work. 70% IPA is more effective than higher concentrations because it penetrates microbial cell walls more efficiently — making it the recommended standard for mycology lab environments.

• Concentration: 70% isopropanol
• Apply to all surfaces, tools, and gloved hands
• Allow to fully air-dry before proceeding

Needles & Tools — Use Pre-Sterilised Gamma Irradiated Needles

Always use pre-sterilised, gamma irradiated needles for inoculation work. These are supplied with every spore syringe from Mushroom Spores UK and provide a guaranteed sterile point of entry — eliminating needle-borne contamination risk entirely.

Aseptic Technique — How to Work Clean in Mycology

Aseptic technique refers to the set of practices used to prevent contamination during inoculation, transfer, and cultivation work. Even with fully sterilised equipment, poor technique can introduce contaminants at the point of use.

Use a Still-Air Box or Glovebox

Always work inside a still-air box (SAB) or glovebox when handling spore syringes, agar plates, or open substrates. A still-air box dramatically reduces airborne contamination by creating a low-turbulence environment with minimal spore and particle movement.

Flame-Sterilise Between Uses

Use a butane or alcohol lamp to flame-sterilise metal tools (scalpels, inoculation loops) between each use. Heat the metal until it glows red, then allow to cool briefly before contact with culture material. Never reuse a needle without sterilisation.

Control Airflow and Breathing

Never talk, cough, or breathe directly over open plates, bags, or syringes. Exhaled air contains bacteria and moisture that are a primary source of contamination in home mycology environments. Wear a face mask when working in non-laminar-flow conditions.

Spotting and Responding to Contamination — What to Do

Early identification of contamination prevents it from spreading to other cultures. Watch for these warning signs:

• Non-white growth — green, blue, black, or yellow patches indicate mould contamination
• Slimy or wet patches — bacterial wet spot contamination
• Strong or sour odour — bacterial or advanced mould contamination
• Unusual texture changes — unexpected soft spots or discolouration on substrate

What to Do If You Find Contamination

If you identify contamination, do not open the bag or container — this will spread spores throughout your workspace. Seal it in a plastic bag and dispose of it in an outdoor bin. Then thoroughly sterilise your entire work area before continuing.

If you need support identifying contamination or replacing a product, contact Mushroom Spores UK directly.

Shop Lab-Grade Mycology Supplies UK

Prevent contamination before it starts with professional-grade mycology supplies from Mushroom Spores UK:

• Agar Plates & Lab Tools for Aseptic Work
• Pre-Sterilised Grain Bags and Substrates UK
• Double-Density Psilocybe cubensis Spore Syringes UK