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Profiles of microfungi – Penicillium chrysogenum and P.expansum
International Journal of Hygiene and Environmental Health
Int. J. Hyg. Environ. Health 206, 65 ± 67 (2003) ¹ Urban & Fischer Verlag http: // www.urbanfischer.de/journals/intjhyg
Technical note Profiles of microfungi ± Penicillium chrysogenum and P. expansum G. Fischer, S. Braun, W. Dott Institute of Hygiene and Environmental Health, University Hospital, RWTH Aachen, Germany Received April 3, 2002 ¥ Revision received June 13, 2002 ¥ Accepted June 30, 2002
Introduction Reports of misidentifications in laboratories working in the field of indoor air hygiene have clearly indicated the need to publish a brief note on typical characters of the two species P. chrysogenum and P. expansum. Although both penicillia are very common and differ considerably in colony morphology, they are likely to be often misidentified, especially if recommendations for culturing (as given in identification keys) are not applied properly. If researchers have limited mycological experience, similarities in micro-morphological structures may lead to inconsistent species determination. P. chrysogenum is one of the most commonly occurring Penicillium species in indoor air. Its numbers can be considerably increased in connection with microbial contamination of building material. In case of significantly higher ratios of cfu per m3 air compared to outdoors, the species (together with A. versicolor) is indicative of fungal contamination on building materials. It is important to mention that P. notatum is a synonym of P. chry-
sogenum, the latter being the valid name. This is of major importance when exposure data are related to health complaints in allergy diagnoses, where the old name is still in use for allergen preparations. P. expansum is known to be the cause of brown rot in pomaceous fruit (apples, pears). According to Pitt (1988) it has been isolated from other living plant tissue, indicating that it is a broad spectrum pathogen. Isolations from saprophytic habitats have been much less frequent, but the species is relatively frequent in the air of composting facilities. It is also not infrequently detected in the atmosphere.
Descriptions Characteristics of P. chrysogenum and P. expansum are given in Table 1 and Figures 1 ± 4. Relevant current literature and keys comprise (Domsch et al., 1993; Larsen and Frisvad, 1995a, b; Pitt, 1979, 1988; Pitt and Hocking, 1985; Samson et al., 1995, 2000). For important metabolites refer to (Fischer, 2000).
Corresponding author: Dr. Guido Fischer, Institute of Hygiene and Environmental Health, University Hospital, RWTH Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany. Phone: 49 241 808 8876, Fax: 49 241 888 8477, Email: [email protected]
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Fig. 1. Colony morphology of P. chrysogenum. From left (above) to right (below): MEA, CYA, YES, CREA. Distinctive features are the yellow pigment on MEA, the abundant production of yellow exudate on CYA (often also present on MEA), more restricted growth on CREA.
Fig. 2. Colony morphology of P. expansum. From left (above) to right (below): MEA, CYA, YES, CREA. Distinctive features are the lanose to fasciculate texture on MEA, the pronounced fasciculate texture on CYA, and the good growth on CREA.
Fig. 3. Conidiophores of P. chrysogenum showing the typical somewhat irregular branching pattern, which clearly separates it from P. expansum [bar: 10 mm].
Fig. 4.
Conidiophores of P. expansum showing more compact conidiophores with a rather regular branching pattern [bar: 10 mm].
Profiles of microfungi
67
Table 1. Characteristics of P. chrysogenum and P. expansum.
Penicillium chrysogenum Thom 1910 Penicillium notatum Westling 1911
Penicillium expansum Link ex Gray 1821
Colonies: on MEA 25 ± 35 mm in 7d, velvety, yellow-green or pale green-blue.
Colonies: on MEA 20 ± 40 mm in 7d, some isolates velutinous, others partly synnematous, dull green, conidiogenesis heavy sometimes becoming crustose, colonies with a zonate appearance. Typical feature: exudate clear to pale orange brown, soluble pigment brownish orange (better on CYA ). Reverse: pale to deep brown ( MEA ). Conidiophores: mononematous or fasciculate to synnematous, typically terverticillate, smooth-walled. Conidia: smooth-walled, ellipsoidal, 3.0 ± 3.5 mm long.
Typical feature: yellow exudate droplets, sometimes developing later. Reverse: pale, yellowish, yellow-brown ( MEA ). Conidiophores: mononematous, usually ter- to quaterverticillate, stipes smooth, somewhat divergent. Conidia: smooth-walled, subglobose to elliptical, less commonly globose, 3.0 ± 4.0 2.8 ± 3.8 mm2. Ecology: ubiquitous fungus, frequent on wetted walls in indoor environments, but also regularly present in low numbers in outdoor air. Odour: fruity, suggesting apples, pineapples. Important metabolites: mycotoxins : meleagrin, penicillin, roquefortin C, secalonic acid D; MVOC : production of 1-octene3-ol, limonene, and b-phellandrene on YES, CMC, and CEA. Differential diagnosis: penicilli less regularly branched and compact than in P. expansum. Variation: Production of biverticillate penicilli can be more or less pronounced, some isolates lack yellow pigmentation and/or exudate production. Affinities: shows an affinity with species in subgenus Furcatum with respect to conidiophore branching, e.g. P. citrinum.
References Domsch, K. H., Gams, W., Anderson, T.±H.: Compendium of soil fungi. Reprint, IHW-Verlag, Eching, Germany (1993). Fischer, G.: Comparison of microbiological and chemical methods for assessing the exposure to air-borne fungi in composting plants. Dissertation. In: Akademische Edition Umweltforschung Band 10 ± Publikationsreihe des interdisziplin‰ren Umwelt-Forums der RWTH Aachen (2000). Pitt, J. I.: The Genus Penicillium, Academic Press, Sydney (1979). Pitt, J. I.: A laboratory guide to common Penicillium species (2nd Edition). CSIRO, Divisoin of Food Research and Processing, North Ryde, NSW, Australia, ISBN 0 ± 643 ± 05837 ± 5 (1988).
Ecology: primary ecological niche is the pomaceous fruit, therefore also regularly present in low numbers in composting facilities, widely distributed soil fungus. Odour: odour aromatic, fruity suggesting apples. Important metabolites: mycotoxins : citrinin, patulin, roquefortine C, chaetoglobosin C; MVOC : production of 1-methoxy-3methylbenzene, aromadendrene, and bicycloelemene was distinctive on YES. Differential diagnosis: penicilli more regularly branched and compact, rami and metulae more appressed than in P. chrysogenum. Variation: Isolates of this species show little variation. Affinities: Similarities in colony morphology (but not in colour) to P. crustosum and P. viridicatum that both have rough stipes ( P. aurantiogriseum complex). Additional notes: The capacity to cause a rapid apple rot has been used as a taxonomic criterion.
Pitt, J. I., Hocking, A. D.: Fungi and Food Spoilage. Academic Press, Sydney (1985). Samson, R. A., Hoekstra, E. S., Frisvad, J. C., Filtenborg, O.: Introduction to food-borne fungi (4th Edition). Centraalbureau voor Schimmelcultures, Baarn, The Netherlands (1995). Samson, R. A., Hoekstra, E. S., Frisvad, J. C., Filtenborg, O.: Introduction to food- and airborne fungi (6th Edition). Centraalbureau voor Schimmelcultures, Baarn, The Netherlands (2000). Larsen, T. O., Frisvad, J. C.: Characterization of volatile metabolites from 47 Penicillium taxa. Mycol. Res. 99, 1153 ± 1166 (1995a). Larsen, T. O., Frisvad, J. C.: Chemosystematics of Penicillium based on profiles of volatile metabolites. Mycol. Res. 99, 1167 ± 1174 (1995b).
Int. J. Hyg. Environ. Health 206, 65 ± 67 (2003) ¹ Urban & Fischer Verlag http: // www.urbanfischer.de/journals/intjhyg
Technical note Profiles of microfungi ± Penicillium chrysogenum and P. expansum G. Fischer, S. Braun, W. Dott Institute of Hygiene and Environmental Health, University Hospital, RWTH Aachen, Germany Received April 3, 2002 ¥ Revision received June 13, 2002 ¥ Accepted June 30, 2002
Introduction Reports of misidentifications in laboratories working in the field of indoor air hygiene have clearly indicated the need to publish a brief note on typical characters of the two species P. chrysogenum and P. expansum. Although both penicillia are very common and differ considerably in colony morphology, they are likely to be often misidentified, especially if recommendations for culturing (as given in identification keys) are not applied properly. If researchers have limited mycological experience, similarities in micro-morphological structures may lead to inconsistent species determination. P. chrysogenum is one of the most commonly occurring Penicillium species in indoor air. Its numbers can be considerably increased in connection with microbial contamination of building material. In case of significantly higher ratios of cfu per m3 air compared to outdoors, the species (together with A. versicolor) is indicative of fungal contamination on building materials. It is important to mention that P. notatum is a synonym of P. chry-
sogenum, the latter being the valid name. This is of major importance when exposure data are related to health complaints in allergy diagnoses, where the old name is still in use for allergen preparations. P. expansum is known to be the cause of brown rot in pomaceous fruit (apples, pears). According to Pitt (1988) it has been isolated from other living plant tissue, indicating that it is a broad spectrum pathogen. Isolations from saprophytic habitats have been much less frequent, but the species is relatively frequent in the air of composting facilities. It is also not infrequently detected in the atmosphere.
Descriptions Characteristics of P. chrysogenum and P. expansum are given in Table 1 and Figures 1 ± 4. Relevant current literature and keys comprise (Domsch et al., 1993; Larsen and Frisvad, 1995a, b; Pitt, 1979, 1988; Pitt and Hocking, 1985; Samson et al., 1995, 2000). For important metabolites refer to (Fischer, 2000).
Corresponding author: Dr. Guido Fischer, Institute of Hygiene and Environmental Health, University Hospital, RWTH Aachen, Pauwelsstr. 30, D-52057 Aachen, Germany. Phone: 49 241 808 8876, Fax: 49 241 888 8477, Email: [email protected]
1438-4639/03/206-65 $ 15.00/0
66
G. Fischer et al.
Fig. 1. Colony morphology of P. chrysogenum. From left (above) to right (below): MEA, CYA, YES, CREA. Distinctive features are the yellow pigment on MEA, the abundant production of yellow exudate on CYA (often also present on MEA), more restricted growth on CREA.
Fig. 2. Colony morphology of P. expansum. From left (above) to right (below): MEA, CYA, YES, CREA. Distinctive features are the lanose to fasciculate texture on MEA, the pronounced fasciculate texture on CYA, and the good growth on CREA.
Fig. 3. Conidiophores of P. chrysogenum showing the typical somewhat irregular branching pattern, which clearly separates it from P. expansum [bar: 10 mm].
Fig. 4.
Conidiophores of P. expansum showing more compact conidiophores with a rather regular branching pattern [bar: 10 mm].
Profiles of microfungi
67
Table 1. Characteristics of P. chrysogenum and P. expansum.
Penicillium chrysogenum Thom 1910 Penicillium notatum Westling 1911
Penicillium expansum Link ex Gray 1821
Colonies: on MEA 25 ± 35 mm in 7d, velvety, yellow-green or pale green-blue.
Colonies: on MEA 20 ± 40 mm in 7d, some isolates velutinous, others partly synnematous, dull green, conidiogenesis heavy sometimes becoming crustose, colonies with a zonate appearance. Typical feature: exudate clear to pale orange brown, soluble pigment brownish orange (better on CYA ). Reverse: pale to deep brown ( MEA ). Conidiophores: mononematous or fasciculate to synnematous, typically terverticillate, smooth-walled. Conidia: smooth-walled, ellipsoidal, 3.0 ± 3.5 mm long.
Typical feature: yellow exudate droplets, sometimes developing later. Reverse: pale, yellowish, yellow-brown ( MEA ). Conidiophores: mononematous, usually ter- to quaterverticillate, stipes smooth, somewhat divergent. Conidia: smooth-walled, subglobose to elliptical, less commonly globose, 3.0 ± 4.0 2.8 ± 3.8 mm2. Ecology: ubiquitous fungus, frequent on wetted walls in indoor environments, but also regularly present in low numbers in outdoor air. Odour: fruity, suggesting apples, pineapples. Important metabolites: mycotoxins : meleagrin, penicillin, roquefortin C, secalonic acid D; MVOC : production of 1-octene3-ol, limonene, and b-phellandrene on YES, CMC, and CEA. Differential diagnosis: penicilli less regularly branched and compact than in P. expansum. Variation: Production of biverticillate penicilli can be more or less pronounced, some isolates lack yellow pigmentation and/or exudate production. Affinities: shows an affinity with species in subgenus Furcatum with respect to conidiophore branching, e.g. P. citrinum.
References Domsch, K. H., Gams, W., Anderson, T.±H.: Compendium of soil fungi. Reprint, IHW-Verlag, Eching, Germany (1993). Fischer, G.: Comparison of microbiological and chemical methods for assessing the exposure to air-borne fungi in composting plants. Dissertation. In: Akademische Edition Umweltforschung Band 10 ± Publikationsreihe des interdisziplin‰ren Umwelt-Forums der RWTH Aachen (2000). Pitt, J. I.: The Genus Penicillium, Academic Press, Sydney (1979). Pitt, J. I.: A laboratory guide to common Penicillium species (2nd Edition). CSIRO, Divisoin of Food Research and Processing, North Ryde, NSW, Australia, ISBN 0 ± 643 ± 05837 ± 5 (1988).
Ecology: primary ecological niche is the pomaceous fruit, therefore also regularly present in low numbers in composting facilities, widely distributed soil fungus. Odour: odour aromatic, fruity suggesting apples. Important metabolites: mycotoxins : citrinin, patulin, roquefortine C, chaetoglobosin C; MVOC : production of 1-methoxy-3methylbenzene, aromadendrene, and bicycloelemene was distinctive on YES. Differential diagnosis: penicilli more regularly branched and compact, rami and metulae more appressed than in P. chrysogenum. Variation: Isolates of this species show little variation. Affinities: Similarities in colony morphology (but not in colour) to P. crustosum and P. viridicatum that both have rough stipes ( P. aurantiogriseum complex). Additional notes: The capacity to cause a rapid apple rot has been used as a taxonomic criterion.
Pitt, J. I., Hocking, A. D.: Fungi and Food Spoilage. Academic Press, Sydney (1985). Samson, R. A., Hoekstra, E. S., Frisvad, J. C., Filtenborg, O.: Introduction to food-borne fungi (4th Edition). Centraalbureau voor Schimmelcultures, Baarn, The Netherlands (1995). Samson, R. A., Hoekstra, E. S., Frisvad, J. C., Filtenborg, O.: Introduction to food- and airborne fungi (6th Edition). Centraalbureau voor Schimmelcultures, Baarn, The Netherlands (2000). Larsen, T. O., Frisvad, J. C.: Characterization of volatile metabolites from 47 Penicillium taxa. Mycol. Res. 99, 1153 ± 1166 (1995a). Larsen, T. O., Frisvad, J. C.: Chemosystematics of Penicillium based on profiles of volatile metabolites. Mycol. Res. 99, 1167 ± 1174 (1995b).