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Paecilomyces sp.

Mitosporic fungus. Hyphomycetes. Teleomorph (sexual state): Byssochlamyes (Ascomycete).



Approx. 9 to 30 species, depending on taxonomic system.

Where Found

Soil and decaying plant material, composting processes, legumes, cottonseeds; some species parasitize insects.

Mode of Dissemination

Dry spore.

Growth Indoors

Has been isolated from jute fibers, paper, PVC, timber (oak wood), optical lenses, leather, photographic paper, cigar tobacco, harvested grapes, bottled fruit, and fruit juice undergoing pasteurization.
P. variotii: Aw=0.84

Industrial Uses

Not known.

Other Comments

Paecilomyces is closely related to Penicillium.

Potential Health Effects


Type I allergies (hay fever, asthma).
Type III hypersensitivity pneumonitis: Humidifier lung.

Potential Opportunist or Pathogen

Although Paecilomyces grows at 37°C, human disease is relatively rare. Mycotic keratitis in conjunction with corneal implants, nosocomial infections, endocarditis, infections in immunocompromised patients are reported.

Potential Toxin Production

Paecilotoxins, byssochlamic acid, variotin, ferrirubin, viriditoxin, indole-3-acetic acid, fusigen and patulin.

Laboratory Notes

Growth/Culture Characterisics

Grows well on general fungal media. Some species produce distinctive pigments such as ocher and lilac. Paecilomyces does not produce blue or green colonies. Paecilomyces variotii is thermophilic (grows up to 55°C).

Spore Trap Recognition

Free spores are similar to Penicillium/Aspergillus.

Tape Lift Recognition

Recognizable if all sporulation structures are present. Conidia are produced in long chains from slender tapering divergent phialides.