About Penicillium decumbens
Penicillium decumbens is a cellulolytic Penicillium of major industrial interest as a cellulase producer (paper-pulp processing, biofuel research). Indoor mycology literature on the species is comparatively thin; most isolations are from soil and decaying plant matter.
Taxonomy
Penicillium section Exilicaulis (modern Houbraken classification; previously placed in subgenus Penicillium in older Pitt 1979 framework)
Ecology and habitat
P. decumbens is cosmopolitan in soil and on cellulose-rich plant substrates. The species's strong cellulase production makes it an important industrial workhorse for paper pulp and biofuel research, but this same trait also gives it ecological adaptation to damp cellulose materials indoors.
Indoor relevance
Indoor isolates are uncommon but not unusual on damp cellulose-containing materials. The species's mycotoxin profile is modest; its diagnostic value on extended panels is principally as another Penicillium present in indoor dust at low frequencies.
Cardinal physiology
Minimum water activity for growth: Aw 0.79[2]. Growth across 5–37 °C with optimum near 25 °C. The species is broadly similar to other small-spored Penicillia in cardinal physiology.
Secondary metabolites
P. decumbens is principally known for cellulase production, which is the basis for its industrial use rather than for a mycotoxin-producing role. Some strains produce penicillic acid; the species is not a documented major mycotoxin concern indoors.
Compounds documented as produced by Penicillium decumbens (presence and quantity vary by chemotype, strain, and substrate):
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.