Xerophilic · Extended-panel species

Aspergillus terreus

Cosmopolitan thermotolerant Aspergillus often found on potted-plant soil and in HVAC dust. Produces citrinin and (some strains) gliotoxin.

Extended panelXerophilic · Aw ≥ 0.78

Moisture niche · where this species can grow

XerophilicAw < 0.80
MesophilicAw 0.80–0.89
HydrophilicAw ≥ 0.90
Min Aw 0.78
← Drier conditions toleratedRequires liquid water →
Minimum Aw
0.78
EPA reference (GM)
< 0.4 SE/mgMeklin AHHS threshold
Mycotoxin profile
5+ documented
Ecological role
Primary colonizer

The < 0.4 SE/mg reference value is Meklin 2004's AHHS exclusion threshold: the paper retained species whose geometric mean was at least 2 spores per 5 mg dust (≈ 0.4 spores/mg) and eliminated the rest. This species was measured across the 1,096-home AHHS sample and characterized below that threshold, used here as a conservative ceiling on its true GM, not a percentile band. A detected value of X SE/mg implies an elevation factor of at least X ÷ 0.4 over the EPA reference, a lower bound, since the true GM is below 0.4. See the 82-species story for the math.

About Aspergillus terreus

Aspergillus terreus is a cosmopolitan soil saprophyte and one of the more thermotolerant and xerotolerant members of the genus. Although not on the EPA's standard 36-species ERMI panel, it is a routine isolate from indoor dust, HVAC systems, and (notably) potted plant soil, an often-overlooked indoor reservoir of fungal biomass.

Taxonomy

Ascomycota → Eurotiomycetes → Eurotiales → Aspergillaceae → Aspergillus section Terrei

Ecology and habitat

A. terreus is found globally in soil, decomposing plant matter, dust, and compost. The species's thermotolerance (growth to 48 °C) and xerotolerance (min Aw 0.78) place it ecologically between the strictly mesophilic A. fumigatus and the more xerophilic small-spored Aspergilli. It is also of long-standing industrial interest as the natural producer of lovastatin (the parent compound of the statin drug class) and itaconic acid.

Indoor relevance

Indoors, A. terreus is most consistently associated with three contexts: HVAC systems (where its thermotolerance and ability to grow on dust-laden surfaces give it an advantage), water-damaged buildings (where its low minimum Aw allows establishment ahead of more hydrophilic species), and indoor potted-plant soil, which is a chronically high-biomass fungal reservoir that homeowner-style sampling rarely accounts for. Its detection in dust panels usually reflects one of these reservoirs rather than fresh structural growth.

Cardinal physiology

Minimum water activity for growth: Aw 0.78[2], which makes A. terreus one of the more xerotolerant Aspergilli. Growth occurs across 10–48 °C with the optimum at 35–40 °C. The species is also unusual for its thermotolerance combined with xerotolerance. Most highly thermotolerant fungi are also hydrophilic, and most xerotolerant fungi prefer cooler temperatures.

Thermotolerant; one of the more xerotolerant Aspergilli.

Secondary metabolites

The principal mycotoxin profile is citrinin (a nephrotoxin shared with several Penicillia) and terrein. A subset of strains produce gliotoxin, the immunosuppressive epipolythiodioxopiperazine more commonly associated with A. fumigatus. From an industrial perspective the species also produces lovastatin and itaconic acid; these are not relevant to indoor exposure but they reinforce that A. terreus is a prolific secondary metabolite producer.

Compounds documented as produced by Aspergillus terreus (presence and quantity vary by chemotype, strain, and substrate):

CitrininTerreinGliotoxin (some strains)Lovastatin (pharmaceutical statin precursor)Itaconic acid (industrial)

DNA-based detection of a mycotoxin-producing species in household dust does not directly establish exposure to that mycotoxin at any specific concentration.

Lab availability

Some commercial dust testing labs offer this species as an extended-panel option. Specific lab coverage changes over time: check with your laboratory for current panel options.

Related

CitrininNephrotoxic polyketide produced by this species (and several Penicillia).GliotoxinImmunosuppressive ETP; produced by some A. terreus strains and primarily by A. fumigatus.Aspergillus fumigatusStandard-ERMI relative; gliotoxin overlap.Beyond the 36

References

  1. Meklin T, Haugland RA, Reponen T, Varma M, Lummus Z, Bernstein D, Wymer LJ, Vesper SJ. Quantitative PCR analysis of house dust can reveal abnormal mold conditions. J Environ Monit. 2004;6(7):615–620.
  2. Pitt JI, Hocking AD. Fungi and Food Spoilage. 3rd ed. New York: Springer; 2009.
  3. Wheeler MH, Stipanovic RD. Melanin biosynthesis and the metabolism of flaviolin and 2-hydroxyjuglone in Wangiella dermatitidis. Arch Microbiol. 1985;142:234–241.