The host range of dermatophytes, it is at all possible? Phenotypic evaluation of the keratinolytic activity of Trichophyton verrucosum clinical isolates

Abstract

Dermatophytes are fungi that have an ability to invade keratinised structures. Enzymes secreted by dermatophytes can underlie fungal survival on the host and development of infection. It is possible that the range of activity of keratinases from various dermatophytes is limited to specific species of animals and groups of people. The aim of this study was to carry out phenotypic analysis of the degree of keratinolytic activity of Trichophyton verrucosum strains using hairs of humans and various animal species as substrates. Our results indicated that the activity of keratinases is substrate-induced. The host range of T. verrucosum can be defined as wide. The highest activity of keratinases was recorded in media containing keratin from cow (Bos taurus) and sheep (Ovis aries) hairs in comparison with that from other tested species. The production of keratin-degrading enzymes is a function of time, with the peak of their activity occurring on day 15 of incubation. The role of keratin-degrading enzymes in the pathogenesis of dermatophytosis is becoming increasingly clearer. Given the conceptual understanding that keratin breakdown may require more than just one enzyme, the use of phenotypic methods is an optimal approach to in vitro study of the decomposition of species-specific keratin.

Keywords: Trichophyton verrucosum; dermatophytes; host range; keratin; keratinase activity.