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Screening the keratinolytic activity of dermatophytes in vitro
K Wawrzkiewicz1, T Wolski, J Lobarzewski
1Institute of Infectious and Invasive Diseases, Agricultural Academy, Lublin, Poland.
Abstract:
Sixteen strains out of 12 species dermatophytes were examined in respect to their ability of utilizing keratin substrates as the only sources of C and N. The employed keratin substrates included a solubilized preparation of feather keratin (KS) and native keratin, guinea pig hair and chicken feathers. It has been shown that the preparation KS constitutes a convenient model for a preliminary estimation of fungal keratinolytic activity and it can be a source of information about the localization of these enzymes. It has been found that, among the 16 fungal strains, 13 strains synthesize mainly intracellular keratinases while 3 strains of T. verrucosum release enzymes mainly to the medium. Native keratin from hair and feathers was degraded only by some of the examined strains which, under the experimental conditions, developed characteristic spore forms. Keratin of guinea pigs hair was attacked only by the T. mentagrophytes strains, T. verrucosum and K. ajelloi, and only T. gallinae grew on native keratin from chicken feathers.
Insights
Dermatophyte fungi utilize keratin as a nutrient source. While some fungi secrete keratinase enzymes, others retain them intracellularly, impacting their ability to degrade native keratin substrates like hair and feathers.
Area of Science:
- Mycology
- Biochemistry
- Dermatology
Background:
- Dermatophytes are fungi that cause skin infections.
- Keratin is a structural protein found in hair, skin, and nails.
- Understanding fungal keratinase activity is crucial for dermatophyte research.
Purpose of the Study:
- To investigate the keratinolytic potential of 12 dermatophyte species.
- To compare the degradation of different keratin substrates (solubilized and native).
- To determine the localization (intracellular vs. extracellular) of keratinase enzymes in these fungi.
Main Methods:
- Culturing 16 dermatophyte strains on keratin-based media.
- Utilizing solubilized feather keratin (KS) and native keratin (guinea pig hair, chicken feathers).
- Observing fungal growth and enzyme secretion patterns.
Main Results:
- Solubilized keratin (KS) served as an effective model for assessing keratinolytic activity.
- 13 out of 16 strains primarily synthesized intracellular keratinases.
- 3 strains (Trichophyton verrucosum) predominantly secreted keratinases.
- Degradation of native keratin was strain-specific; only certain strains grew on hair and feathers.
- Trichophyton mentagrophytes, T. verrucosum, and K przeci ajelloi degraded guinea pig hair keratin.
- Trichophyton gallinae exclusively utilized chicken feather keratin.
Conclusions:
- Keratinolytic activity and enzyme localization vary significantly among dermatophyte species.
- The ability to degrade native keratin substrates is limited and species-dependent.
- Keratinase enzyme localization influences the fungus's capacity to utilize keratin as a nutrient source.