Keratinolytic activity of five human isolates of the dermatophytes

The keratinolytic activity of five species of the dermatophytes which include Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Microsporum audouinii and M. gypseum isolated from school children were tested using human hair as the substrate. M. gypseum was found to possess the highest keratinolytic activity with a net value of released protein being 78.8 ug/ml after five weeks of incubation. Also the net value of released protein for T. tonsurans, T. rubrum, T. mentagrophytes and M. audouinii were 55.5 ug/ml, 52.5 ug/ml, 43.8 ug/ml and 26.3 ug/\ml respectively. Only T. mentagrophytes and M. gypseum were able to cause structural damage in form of perforations on the hair shaft. Also during the degradation of the hair, the pH of the basal medium for each dermatophyte increased. The increase in pH was highest in the medium with M. gypseum but lowest in that of M. audouinii.