About Trichoderma viride
Trichoderma viride is a fast-growing, bright green mold most commonly found on very wet building materials, particularly water-saturated wood, gypsum board, and paint. As a tertiary colonizer, it requires high moisture levels to establish growth, so it is generally associated with materials that have been very wet. It has been found growing alongside Stachybotrys chartarum in severely water-damaged buildings and is also a documented allergen.
Ecology and water requirements
Trichoderma viride is classified as a tertiary colonizer in the ecological succession that follows water damage in indoor environments. Primary colonizers (xerophilic Penicillium and Aspergillus species) establish first on damp materials at relatively low water activity; secondary colonizers (Cladosporium) follow as moisture stabilizes; tertiary species like Trichoderma viride require sustained, high water activity (Aw 0.90 or above)[2] and typically appear after weeks to months of continuous wetness. Because of this requirement, its detection in indoor dust samples is one of the more diagnostic available signals of significant, sustained water intrusion[4], distinct from elevated humidity alone. The species cannot establish on materials that dry between wetting events; persistent water contact with cellulose-containing or other organic substrates is required.
Mycotoxin biology
Trichoderma viride produces a range of secondary metabolites with biological activity. The compounds documented in the literature for this species are listed in the chips below. Mycotoxin production is not uniform across all strains and is influenced by substrate, temperature, and water activity[3]. The same isolate may produce substantially different metabolite profiles on drywall paper versus wood versus settled dust[5]. DNA-based detection via the ERMI panel identifies species presence but does not directly measure mycotoxin presence; detection of a mycotoxin-producing species in household dust does not establish exposure to that mycotoxin at any specific concentration.
Detection in dust versus visual inspection
DNA-based detection of Trichoderma viride in settled household dust (the basis of the ERMI panel[1]) integrates spore material from current and recent growth in the home, capturing exposure history over weeks to months. A positive detection in dust does not necessarily indicate currently-active growth at the time of sampling; conversely, an active growth site can produce relatively low dust spore counts if the spores are not being aerosolized (sealed wall cavities, behind vapor barriers, or under flooring). Interpretation requires considering the dust signal alongside building inspection, occupant symptom history, and the broader pattern of species detected on the panel.
Where it’s typically found
Trichoderma viride is documented on the following substrates and locations:
- Water-saturated wood
- gypsum board
- paint
- linoleum
- domestic water supply
- HVAC systems
- carpet dust
Mycotoxins
Compounds documented as produced by Trichoderma viride (presence and quantity vary by chemotype, strain, and substrate):
Mycotoxin production is not uniform across all strains and is influenced by substrate, temperature, and water activity. Detection of a mycotoxin-producing species in household dust does not directly establish exposure to that mycotoxin at any specific concentration.
On your ERMI report
Trichoderma viride is one of the 26 EPA water-damage indicator species used to compute the SLG1 component of the ERMI score (sometimes labeled "Group 1" in EPA documentation). Whether the level detected in any specific home is concerning depends on the broader pattern: which other species are elevated, the water-activity profile of the elevated species, the home's climate context, and (where relevant) the occupant's sensitivity history. Our interpretation report puts Trichoderma viride in that broader pattern.
Mycotoxins and extended panels
Related reference pages: the mycotoxins Trichoderma viride can produce, and the extended-panel species most closely related to it:
Related species
References
- Vesper SJ, McKinstry C, Haugland RA, et al. Development of an Environmental Relative Moldiness Index for U.S. homes. J Occup Environ Med. 2007;49(8):829–833.
- Pitt JI, Hocking AD. Fungi and Food Spoilage. 3rd ed. New York: Springer; 2009.
- Nielsen KF. Mycotoxin production by indoor molds. Fungal Genet Biol. 2003;39(2):103–117.
- Institute of Medicine. Damp Indoor Spaces and Health. Washington, DC: National Academies Press; 2004.
- Miller JD, McMullin DR. Fungal secondary metabolites as harmful indoor air contaminants: 10 years on. Appl Microbiol Biotechnol. 2014;98(24):9953–9966.