Paecilomyces variotii
From Wikipedia, the free encyclopedia
| Paecilomyces variotii | |
|---|---|
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Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Eurotiomycetes |
| Order: | Eurotiales |
| Family: | Thermoascaceae |
| Genus: | Paecilomyces |
| Species: | P. variotii |
| Binomial name | |
| Paecilomyces variotii Bainier (1907) | |
| Synonyms | |
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Paecilomyces variotii, also known by the name Byssochlamys spectabilis for the sexual state, is a common environmental mold from the Phylum Ascomycota (Family Thermoascaceae).[1] It is widespread in the environment and can be found in composts, soils and wood,[2][3][4] as well as a common environmental contaminant in indoor air and carpet dust.[5] Ascospores of the sexual state of P. variotii (B. spectabilis) are strongly heat-resistant. As such the fungus is a common contaminant of heat-treated foods and juices. Paecilomyces variotii has been associated with a number of infective diseases of humans and animals.[6]
Paecilomyces variotii was first described by Georges Bainier in 1907, while its teleomorph was described in 1994 and ranked in Byssochlamys. P. variotii is closely related to P. brunneolus, P. formosus, P. divaricatus and P. dactylethromorphus.[7]
Morphology
Paecilomyces variotii is fast growing, producing powdery to suede-like colonies that are yellow-brown or sand-colored.[8] It is distinguishable from microscopically similar microfungi, such as the biverticillate members of the genus Penicillium (affiliated with the genus Talaromyces) by its broadly ellipsoidal to lemon-shaped conidia, loosely branched conidiophores and phialides with pointed tips.
The colonies are usually flat, powdery to suede-like and funiculose or tufted.[9] The color is initially white, and becomes yellow, yellow-brown, or sand-colored as they mature. A sweet aromatic odor may be associated with older cultures.[10] Colonies of P. variotii are fast growing and mature within 3 days. Colonies grown on Sabouraud's dextrose agar reach about 7–8 mm after one week. Colonies on CYA are flat, floccose in texture, produce brown or olive brown from conidia, and range in diameter from 30 to 79 mmn in one week.[11] Colonies on malt extract agar reach 70 mm diameter or more, otherwise very similar in appearance to those on CYA. Colonies on G25N media reach 8–16 mm diameter, similar to on CYA but with predominantly white mycelium. Microscopically, the spore-bearing structures of P. variotii consist of a loosely branched,[12] irregularly brush-like conidiophores with phialides at the tips.[7][9] The phialides are swollen at the base, and gradually taper to a sharp point at the tip.[12] Conidia are single-celled, hyaline, and are borne in chains with the youngest at the base.[7] Chlamydospores (thick-walled vegetative resting structures) are occasionally produced singly or in short chains.[13]
The teleomorph of Paecilomyces variotii has also been described by the name Byssochlamys spectabilis.[7] However, the Byssochlamys state is rarely observed in culture due to the heterothallic nature of this species (i.e., it requires culturing of positive and negative strains in co-culture to produce the teleomorph).
Genetics
This fungus is heterothallic, and mating experiments have shown that P. variotii can form ascomata and ascospores in culture when compatible mating types are present.[2][7]
The teleomorph of P. variotii, Byssochlamys spectabilis, is rarely observed in cultures from environmental or clinical specimens, which tend to be colonized by a single mating type.[7] The genome sequences of two isolates of P. variotii of opposite mating type have been generated.[14]