Sterilized

In common vernacular, sterilization, disinfection, and pasteurization are loosely interchangeable; but in the context of mushroom cultivation they each have a different and specific meaning. Sterilization is a crucial step in cultivation to prevent contamination and promote healthy growth of the desired mushroom species. Sterilization is often incorrectly thought to create completely axenic conditions; however this is almost never the case. Rather, most sterilization techniques eliminate the majority (ie, 99.9%+) of microbes to allow the mushroom inoculant of choice to colonize a medium with little interspecies competition, such as bacterial, molds, yeasts, or other fungi that may have been present before sterilization.

The most common technique for small and medium scale cultivators is steam sterilization using a pressure cooker. The substrate is placed in a container and sterilized under high pressure and temperature, typically at 15 psi and 121°C (250°F) for 1-2 hours depending on the media or substrate being sterilized.

Autoclaving is a technique usually used in research laboratories and commercial cultivation facilities. This method uses steam and pressure to sterilize equipment, media, and substrates. The items to be sterilized are placed in a chamber and exposed to steam under high pressure and temperature, typically at 15 psi and 121°C (250°F) for 1-2 hours.

Chemical sterilization is sometimes used when other sterilization equipment is unavailable. Chemicals such as hydrogen peroxide, bleach, and ethanol can be used to sterilize surfaces, equipment, and tools. The concentration and contact time of the sterilizing solution will depend on the specific chemical and the item being sterilized.

Hot water treatment is a technique used to sterilize seeds or small items such as spore syringes. The item is placed in hot water at a temperature of 80-90°C (176-194°F) for 30 minutes to an hour.

UV-C light is infrequently utilized, because of the specialized nature of the equipment and its relative lack of efficacy compared to other more traditional methods. UV sterilization involves exposing surfaces, equipment, and tools used in MC to UV-C light, which has germicidal properties and can kill microorganisms. It's usefulness is limited because unlike methods such as steam sterilization, UV-C light is limited to only sterilizing surfaces and has little to no penetration. The appropriate wavelength and intensity must be considered when choosing a UV-C light, as only a very narrow band of wavelengths has antimicrobial properties and intensity is correlated to the required exposure time for effective disinfection.