Genus overview
The Penicillium genus.
Penicillium is one of the most ecologically and industrially significant fungal genera. Its members include xerotolerant primary colonizers, postharvest fruit pathogens, cheese starter cultures, the source of the original penicillin drug class, and several major mycotoxin producers. This page inventories which Penicillia appear on the standard ERMI, which are added by extended panels, and which minor species are mentioned only here.
About the genus
Penicillium is taxonomically placed in Ascomycota → Eurotiomycetes → Eurotiales → Aspergillaceae. The genus contains approximately 483 accepted species in modern taxonomy (Houbraken et al. 2020), up from ~354 in the 2014 Visagie/Houbraken/Frisvad monograph. Most are soil saprophytes or food-spoilage organisms, but several are major postharvest pathogens (P. expansum, P. digitatum, P. italicum) and several produce mycotoxins of regulatory or building-mycology concern.
Ecologically, most indoor-relevant Penicillia are xerotolerant, capable of growth at lower water activity than the more hydrophilic water-damage indicators like Stachybotrys. This is why an ERMI panel will frequently show elevated Penicillium counts in homes that are humid but not actively wet, and why Penicillium dominance in a panel pattern can point to chronic-humidity rather than acute-flood scenarios.
Penicillium species on the standard ERMI 36
ERMI 36
Penicillium brevicompactum
Major mycophenolic acid producer; xerotolerant primary colonizer.
ERMI 36
Penicillium chrysogenum
Group 2 environmental reference; producer of penicillin (industrial) and roquefortine C.
ERMI 36
Penicillium corylophilum
Water-damage indicator; minor mycotoxin profile.
ERMI 36
Penicillium crustosum
Penitrem A and roquefortine C producer; common indoor isolate.
ERMI 36
Penicillium purpurogenum
Mitorubrin / rubratoxin producer; water-damage indicator.
ERMI 36
Penicillium spinulosum / glabrum
Water-damage indicator; minor toxin profile.
ERMI 36
Penicillium variabile
Water-damage indicator on the ERMI panel; allergen primarily.
Extended-panel Penicillium species
Extended species
Penicillium aurantiogriseum / P. viridicatum
Historical Penicillium OTA route; cool-storage cereal colonizers.
Extended species
Penicillium expansum
Apple-juice 'blue mold' pathogen; documented indoors on gypsum board (Salo et al. 2019) with chaetoglobosin and communesin guttation droplets.
Extended species
Penicillium citrinum
Among the most ubiquitous Penicillia globally; namesake citrinin producer.
Extended species
Penicillium roqueforti
Blue-cheese culture organism and mycophenolic acid producer in moisture-damaged buildings.
Extended species
Penicillium citreonigrum
Stored-grain Penicillium. Citreoviridin producer; limited modern indoor relevance.
Extended species
Penicillium decumbens
Soil and cellulose-degrading saprophyte; cellulase producer of industrial interest.
Extended species
Penicillium oxalicum
Common soil and substrate saprophyte; secalonic acid D and oxaline producer.
Extended species
Penicillium sclerotiorum
Pigmented (orange-yellow) species producing sclerotiorin and related azaphilones.