Keratinolysis and its morphological expression in hair digestion by airborne fungi

The morphological expression of keratinolysis in fungi isolated from the air of Torino (98 isolates belonging to 36 species) was studied. Light microscopy on whole material and on semithin sections, as well as scanning electron microscopy was used. There were 19 keratinolytically active species, with seven in the genusChrysosporium (C. indicum, C. keratinophilum, C. pannicola, C. tropicum, C. an.Arthroderma cuniculi, C. an.Pectinotrichum llanense, C. an.Renispora flavissima), four in the genusMalbranchea (M. arcuata, M. fulva, M. sulphurea, M. st.Uncinocarpus reesii), and three in the genusTrichophyton (T. mentagrophytes, T. rubrum, T. terrestre). In addition there wereAphanoascus fulvescens, Beauveria bassiana, Geomyces pannorum v.pannorum, Gymnoascus umbrinus andMyceliophthora vellerea. Most of these species were capable of developing structures related to surface erosion and radial penetration contemporaneously. HoweverGymnoascus umbrinus, Myceliophthora vellerea, an isolate ofC. indicum, C. tropicum andTrichophyton mentagrophytes demonstrated only surface erosion. Different isolates of one species can vary in their production of invasive structures and in degree of keratinolytic activity. Thus such activity, like many biochemical activities of fungi, does not appear to be a constant or rigorously species-specific character.