Extended-panel species

Memnoniella echinata

Stachybotrys's closest cellulose-degrading relative. Co-occurs with S. chartarum on wet drywall; produces simple trichothecenes (trichodermin, trichodermol) and griseofulvins.

Extended panel
Minimum Aw
–
EPA reference (GM)
< 0.4 SE/mgMeklin AHHS threshold
Mycotoxin profile
4+ documented
Ecological role
Variable

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.

Note on cardinal Aw: No species-specific value measured: Food and Indoor Fungi (Samson et al.) states concrete Aw data are not known. Hydrophilic; grows poorly on DG18 osmotic-stress agar. Now congeneric with Stachybotrys (Wang et al. 2015). Estimated min Aw ≈ 0.94 by analogy with S. chartarum (min ~0.94; germination demonstrated to ~0.92).

About Memnoniella echinata

Memnoniella echinata is a cellulose-degrading hyphomycete phylogenetically close to Stachybotrys chartarum and frequently co-occurring with it on water-damaged drywall, ceiling tile, and paper substrates. It is the only Stachybotrys-adjacent species commercially offered on extended ERMI-style panels, and it adds diagnostic value because its dry spore chains aerosolize more readily than Stachybotrys's wet spore mass.

Taxonomy

Ascomycota → Sordariomycetes → Hypocreales → Stachybotryaceae → Memnoniella. Phylogenetically close to Stachybotrys; sometimes treated within Stachybotrys sensu lato in modern revisions.

Ecology and habitat

M. echinata is strongly cellulolytic. It has been isolated from cotton, canvas, hardboard, woolen fabric, paper, wood, and soil in tropical and subtropical regions. Indoors it co-occurs with S. chartarum on the same substrates (wet drywall, ceiling tile paper, water-damaged cardboard), but with different aerosolization behavior. Where Stachybotrys produces spores in a wet sticky mass that stays put, Memnoniella produces dry conidia in chains that release into indoor air with comparatively minor disturbance.

Indoor relevance

M. echinata co-occurs with S. chartarum on water-damaged drywall, ceiling tile, and paper substrates[3]. The dry-spore aerosolization mechanic is important here: a building with Memnoniella growth can deliver airborne spore burden under conditions (light air currents, vacuuming, HVAC operation) that would not appreciably aerosolize Stachybotrys growth.

Cardinal physiology

No species-specific cardinal Aw has been measured for M. echinata. The standard reference Food and Indoor Fungi (Samson et al.) explicitly states concrete Aw data are not known. The species is a hydrophilic tertiary colonizer that grows poorly on DG18 osmotic-stress agar, consistent with a high water requirement. The most defensible estimate is a minimum Aw ≈ 0.94 by analogy with Stachybotrys chartarum (now its congeneric relative; Wang et al. 2015, Fungal Diversity 71), whose minimum is ~0.94 with germination demonstrated down to ~0.92 (Gravesen et al. 1999; Frankel et al., Mycopathologia 2011). Treat this as an estimate, not a measurement for Memnoniella itself.

Secondary metabolites

M. echinata produces simple (Type A) trichothecenes (primarily trichodermin and trichodermol[3]), distinct from the macrocyclic trichothecenes (satratoxins, roridins, verrucarins) that Stachybotrys produces. The species is also the first non-Penicillium genus documented to produce griseofulvins (dechlorogriseofulvin, epidechlorogriseofulvin)[2], an unusual and taxonomically informative finding. Trichodermin and trichodermol are potent inhibitors of eukaryotic ribosomal protein synthesis, the same mechanism as the macrocyclic trichothecenes but with markedly different chemistry.

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

Trichodermin (simple trichothecene)TrichodermolDechlorogriseofulvinEpidechlorogriseofulvin

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

TrichothecenesSimple trichothecenes (trichodermin, trichodermol) produced by this species.Stachybotrys chartarumClosest standard-ERMI relative; macrocyclic trichothecene producer.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. Jarvis BB, Zhou Y, Wang S, Sorenson WG, Hintikka EL, Nikulin M, Parikka P, Etzel RA, Dearborn DG. Toxigenic molds in water-damaged buildings: dechlorogriseofulvins from Memnoniella echinata. J Nat Prod. 1996;59:553–554.
  3. Jarvis BB, Sorenson WG, Hintikka EL, et al. Study of toxin production by isolates of Stachybotrys chartarum and Memnoniella echinata from a water-damaged building. Appl Environ Microbiol. 1998;64:3620–3625.