What is the Mushchamber Test Chamber?

Mushchamber cultivation is a complex process that is divided into several phases.

Fortunately, modern technologies make this process easier, ensuring precision and reliability.

The Mushchamber Test Chamber is one of these technologies.

But how does mushchamber cultivation work, how many phases does it involve , and how does the Mushchamber Test Chamber help us?

In the following article, we will answer all these questions.

Mushchamber Cultivation: The Colonization Phase

Colonization is the initial phase of mushchamber cultivation, during which the mycelium colonizes the substrate. To ensure successful colonization, it is essential to maintain certain environmental conditions:

• Humidity: Mushchambers thrive in humidity between 90% and 100%. This humidity level helps keep the substrate hydrated, promoting mycelium growth.
• Free Water: A high amount of free water in the substrate is required to support fungal growth.
• Temperature: The optimal temperature varies depending on the species, but is generally between 20°C and 30°C. This range favors enzymatic activity and mycelium metabolism.
• Nutrients: Mushchambers require a variety of nutrients, including minerals, sugars, proteins, vitamins, and fatty acids.

During this stage, it's crucial to avoid direct light and maintain stable conditions to allow the mycelium to develop evenly. Cleaning and sterilizing the substrate and growing environment are equally essential to prevent contamination.

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Mushchamber Cultivation: The Fruiting Stage

Fruiting is the stage in which the mycelium produces the fruiting bodies, or mushchambers themselves. The optimal conditions for fruiting vary depending on the type of mushchamber, but generally they are:

Temperature: Most mushchambers fruit well between 12°C and 24°C.

Humidity:relative humidity , often between 75% and 95%, is crucial for fruiting.

Lighting: Although mushchambers don't require light for mycelium growth, some types require a certain amount of light to trigger fruiting. Indirect light or fluorescent lighting with a 12-hour light/dark cycle is often ideal.

Ventilation: Good air circulation is important to provide fresh oxygen and prevent the buildup of carbon dioxide, which can inhibit fruiting.

Learn more: Discover our CO2 and modified atmosphere climate chamber, designed and manufactured by FDM Environment Makers.

How the Mushchamber Test Chamber is Made

The Mushchamber Test Chamber is a laboratory instrument capable of replicating and maintaining ideal conditions for both stages of cultivation. The main characteristics of a good fruiting chamber include:

Temperature Range: It must cover a range from 0°C to 70°C to adapt to the different needs of fungal species.

Humidity Range: It must allow you to regulate humidity between 10% and 98%.

LED lighting: Must be equipped with vertical dimmable LED lights, with the possibility of reducing the light intensity to below 50% of the standard.

Ventilation: This is essential to prevent carbon dioxide buildup. A CO2 probe can be used to monitor carbon dioxide levels and activate an exhaust fan to bring in fresh air.

HEPA filters: These must be installed at the inlet and outlet to prevent contamination from external agents and to filter out fungal spores.

UV Sterilization: It can be used to sterilize the water and air in the chamber, ensuring a contamination-free environment.

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The FDM Mushchamber Test Chamber

FDM has been a leader in climate simulation for over 70 years. 

Our growth chambers are suitable for growing numerous organisms and microorganisms, including fungi.

FDM growth chambers possess all the basic characteristics for the cultivation of plant species and can be configured, upon customer request, for the specific cultivation of mushchambers with all the features listed above.

To find out more, please contact us.

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Reference Standards

• ISO 846 — Plastics: Evaluation of the action of microorganisms, reference method for biodegradation and fungal resistance of polymers.
• ASTM G21 — Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi, American test for coatings and technical plastics.
• JIS Z 2911 — Methods of test for fungus resistance, a Japanese standard used in the Asian electronics and automotive industries.
• MIL-STD-810H Method 508.8 — Fungus: Military method for qualifying hardware exposed to microorganisms in a tropical environment.
• IEC 60068-2-10 — Test J: Mould growth, European test procedure for resistance to mould on electrotechnical materials.
• ISO 16869 — Plastics: Assessment of the effectiveness of fungistatic compounds in plastics, testing the effectiveness of incorporated biocides.

Authoritative Sources

• ISO – International Organization for Standardization. It manages ISO 846 and ISO 16869 for plastic biodegradation testing.
• ASTM G21. Reference Standard for Fungal Resistance of Synthetic Polymeric Materials.
• JSA – Japanese Standards Association. Publishes the JIS Z 2911 series for mold resistance testing.

Frequently Asked Questions about the Mushchamber Test Chamber

Which standard fungal strains should I use?

The regulations converge on a pool of five fungal species representative of tropical biodeterioration: Aspergillus niger (ATCC 9642), a ubiquitous saprophyte with acid metabolism; Aspergillus flavus (ATCC 9643), an aflatoxin producer on organic substrates; Penicillium funiculosum (ATCC 11797), a colonizer of plastics and paints; Chaetomium globosum (ATCC 6205), a cellulolytic specialist on cotton and cellulose; and Trichoderma virens (ATCC 9645), an antagonist with the production of lytic enzymes. The inoculum is prepared from pure cultures on Czapek-Dox agar at 28°C for 10–14 days, harvesting spores in Bushnell-Haas mineral solution with 0.05% Tween 80. The final concentration is 1.6 spores/mL for each strain, with an equimolar mixture of the five species. The conservation of ATCC/DSMZ strains ensures genetic stability and inter-laboratory reproducibility; "wild" environmental strains are not permitted for accredited testing.

What are the environmental conditions in the chamber?

Standard conditions for accelerated fungal growth are 28-30 C and >= 95% RH maintained constantly for 28 days according to ASTM G21 and ISO 846. MIL-STD-810 Method 508 requires 30 days at 30 C and 95% RH with a 12/12 h light/dark cycle to stimulate sporulation. The chamber must provide: (1) continuous humidification with atomized deionized water (ultrasonic solenoid valve); (2) slow air circulation (0.1-0.3 m/s) to avoid drying out surfaces; (3) uniform distribution +/- 2% RH in the mapped usable volume; (4) condensation drainage from the bottom; (5) HEPA H14 filtration for fresh air to avoid external contamination; (6) anti-corrosion internal materials (SS 316L, PP) to withstand the acidic environment generated by fungal metabolites. Calibration of the RH should be performed with saturated saline solutions (KNO3 93.6% RH at 30 C) every 6 months.

How to evaluate fungal growth?

The evaluation is semi-quantitative with a 0-5 scale according to ASTM G21 and MIL-STD-810: Grade 0 no growth observable under a 50x microscope; Grade 1 traces of growth ( Grade 2 light growth (10-30%); Grade 3 moderate growth (30-60%); Grade 4 heavy growth (60-90%); Grade 5 total coverage. The evaluation is performed at 7, 14, 21, 28 days by comparing with positive control samples (cotton) to validate inoculum viability and negative control (sterile Petri paper). For electronics and photovoltaics, functional measurements are added: surface resistance, breakdown voltage, insulation at 500 Vdc according to IEC 60112. The results are reported in the table for each measurement point with documentary photos under a 10-50x stereo microscope. Typical pass criteria: Grade

Need mushchamber testing for consumer electronics?

It depends on the target market and the specifications. For indoor consumer applications in temperate climates (Europe, North America) fungal testing is not mandatory. It is however required for: (1) outdoor devices or in humid tropical environments (South-East Asia, Latin America, Africa), where Aspergillus niger can cause PCB corrosion in 6-12 months; (2) medical electronics for developing countries according to WHO PQS; (3) military hardware MIL-STD-810 Method 508 for Middle East and tropics; (4) outdoor telecommunication ITU-T K series; (5) photovoltaics for tropical markets IEC 62892. Typical failure modes include copper corrosion by fungal organic acids (pH 2-3 locally), fungal growth on old conformal coating with delamination, surface tracking at high voltage. The fungi qualification is usually combined with damp heat steady state IEC 60068-2-78 and salt mist ISO 9227 to cover the entire tropical degradation spectrum.