Mesophilic · Extended-panel species

Fusarium species

Soil and plant-pathogen genus whose indoor presence indicates water damage on carpets, drywall, or HVAC. Source of fumonisins, trichothecenes (T-2/HT-2/DON), and zearalenone depending on species.

Extended panelMesophilic · Aw ≥ 0.87

Moisture niche · where this species can grow

XerophilicAw < 0.80
MesophilicAw 0.80–0.89
HydrophilicAw ≥ 0.90
Min Aw 0.87
← Drier conditions toleratedRequires liquid water →
Minimum Aw
0.87
EPA reference (GM)
Not measurednot in 82-panel
Mycotoxin profile
6+ documented
Ecological role
Secondary colonizer

Note on cardinal Aw: Substrate- and species-dependent. On cereal grain: F. culmorum and F. graminearum minimum ~0.90 (Hope et al. 2005 on wheat); F. verticillioides and F. proliferatum can grow at 0.85–0.87 on optimal media (some Marin et al. studies) but commonly reported at ~0.90 minimum on grain.

About Fusarium species

Fusarium is a globally distributed genus of soil and plant-pathogenic fungi. It is one of the most consequential omissions from the standard 36-species ERMI panel because several Fusarium species are the principal indoor or grain-borne route for three major mycotoxin families: trichothecenes (T-2, HT-2, DON, NIV), zearalenone, and fumonisins.

Taxonomy

Ascomycota → Sordariomycetes → Hypocreales → Nectriaceae → Fusarium. The Fusarium solani species complex (FSSC) alone is currently estimated to contain 50+ phylogenetically distinct species.

Ecology and habitat

Most Fusarium species are soil saprophytes or plant pathogens that cause root rots, head blight in cereals (F. graminearum, F. culmorum), ear rot in maize (F. verticillioides, F. proliferatum), and wilts (F. oxysporum). The F. solani species complex (FSSC) is taxonomically the most diverse (50+ phylogenetic species) and contains the principal opportunistic human and animal pathogens. The genus thrives across 5–40 °C with an optimum near 25–30 °C[2].

Indoor relevance

Indoors, Fusarium is associated with water-damaged carpets, gypsum board, humidifier reservoirs, and contaminated HVAC components[4][5]. Per industrial hygiene literature, indoor airborne spore counts for Fusarium are rarely high. A few spores indoors can indicate serious mold growth somewhere on the structure. The genus can colonize aqueous indoor reservoirs (drains, humidifier sumps, biofilm-laden plumbing) in addition to wet structural materials.

What your lab report shows. Commercial dust-qPCR labs differ in which Fusarium target they use. Some labs (e.g., RealTime Labs in the US) test the F. solani species complex (FSSC) specifically, which itself contains 50+ phylogenetically distinct species. Other labs (e.g., Mould Lab UK, Farmacy, Hey Hey MAE, PJ Harlow in Europe) test at the genus level, which captures any Fusarium DNA including F. graminearum, F. oxysporum, F. verticillioides, F. proliferatum, F. sporotrichioides, F. culmorum, and others. Either way, the result is reported on your lab sheet as "Fusarium" or "Fusarium spp.", a single value representing the total Fusarium DNA the assay detected. Enter whatever number your lab reported; ExplainmyERMI doesn't need to know which assay was used.

Cardinal physiology

Aw requirements are substrate- and species-dependent. F. solani grows at Aw ≥ ~0.87[3]. F. verticillioides and F. proliferatum have been reported with growth minima as low as 0.85–0.87 on optimal media, with ~0.90 commonly reported on grain (Marin et al. 1995)[2]. F. culmorum and F. graminearum on wheat grain have minimum Aw ~0.90 with optimum ~0.98 (Hope et al. 2005). Production thresholds for mycotoxins are typically higher than growth thresholds, DON production by F. culmorum/F. graminearum occurs over a much narrower range (~0.96–0.995) than growth, and production depends strongly on substrate, competing microflora, and temperature. Field-spike trichothecene production by F. graminearum is favored at cooler temperatures than vegetative growth.

Secondary metabolites

Mycotoxin profiles are species-specific and well-characterized:

  • F. solani: fusaric acid, naphthoquinones; some isolates produce simple trichothecenes
  • F. verticillioides / F. proliferatum: fumonisins (FB1, FB2, FB3; the primary indoor-relevance route)
  • F. graminearum / F. culmorum: deoxynivalenol (DON), zearalenone, nivalenol (Type B trichothecenes)
  • F. sporotrichioides / F. langsethiae: T-2 and HT-2 toxin (Type A trichothecenes)
  • F. poae: primarily nivalenol (NIV); historical attribution of T-2/HT-2 to F. poae is contested (Wilson et al. 2024 J Agric Food Chem)
  • F. avenaceum: moniliformin, beauvericin, enniatins (does not produce trichothecenes)

Genus-level dust DNA detection cannot resolve which Fusarium species is present without species-specific assays. RealTime EMMA reports at the F. solani level; the European-market labs (Mould Lab UK, Farmacy, Hey Hey MAE, PJ Harlow) report at genus level only.

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

Trichothecenes Type A: T-2, HT-2 (F. sporotrichioides, F. langsethiae)Trichothecenes Type B: DON, NIV (F. graminearum, F. culmorum, F. poae principally NIV)Zearalenone (F. graminearum, F. culmorum)Fumonisins (F. verticillioides, F. proliferatum)Moniliformin, beauvericin, enniatins (F. avenaceum: does not produce trichothecenes)Fusaric acid, naphthoquinones (F. solani)

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

TrichothecenesT-2, HT-2, DON, NIV, Fusarium-route producers.ZearalenoneMycoestrogen from F. graminearum / F. culmorum.FumonisinsSphinganine-analog from F. verticillioides / F. proliferatum.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. Marín S, Sanchis V, Magan N. Water activity, temperature, and pH effects on growth of Fusarium moniliforme and Fusarium proliferatum isolates from maize. Can J Microbiol. 1995;41:1063–1070.
  3. Tournas V. Heat-resistant fungi of importance to the food and beverage industry. Crit Rev Microbiol. 1994;20(4):243–263.
  4. Institut national de santé publique du Québec (INSPQ). Fungi: Fusarium spp. Fact sheet. Québec: INSPQ.
  5. Andersen B, Frisvad JC, Søndergaard I, Rasmussen IS, Larsen LS. Associations between fungal species and water-damaged building materials. Appl Environ Microbiol. 2011;77(12):4180–4188.