Wallemia sebi

Mitosporic fungus. Hyphomycetes.

Characteristics

Distribution

Ubiquitous;
cosmopolitan.
Monotypic.

Where Found

Soil, good stuffs, hay, textiles. Grows on salted fish.

Mode of Dissemination

Dry spore.
Wind.

Growth Indoors

Wallemia grows on relatively dry surfaces; found on wood in crawl spaces. Common in mattress dust; may colonize human skin scales.
Aw=0.69-0.75

Industrial Uses

Not known.

Other Comments

Wallemia is a keratinophilic, osmophilic fungus (grows on highly concentrated solutions e.g. salt and sugar).

Potential Health Effects

Allergens

Known allergen.
Type I allergies (hay fever, asthma).

Potential Opportunist or Pathogen

Rare human abscess reported.

Potential Toxin Production

Walleminol, tryptophol and UCA 1064-beta.

Laboratory Notes

Growth/Culture Characteristics

Poor growth on general fungal media. Grows on specialized fungal media with high osmotic pressure. Forms very small tan elevated colonies on DG18 and MEA. While an occasional colony will appear on malt agar, Wallemia may be missed when this is the only media used.

Spore Trap Recognition

Very small cubical (initially) light brown spores formed in chains of four. Recognizable when young, fresh, and when still in chains.

Tape Lift Recognition

Distinctive and identifiable on tape lifts. Observation of sporulating structures may require 1000X magnification (oil immersion).