Mating Behavior of 334 Japanese Isolates of Trichophyton Mentagrophytes in Relation to Their Ecological Status

SUMMARY

A mating study performed by crossing 334 Japanese isolates of Trichophyton mentagrophytes with “+” and “-” tester strains of Arthroderma simii, A. benhamiae and A. vanbreuseghemii revealed that T. mentagrophytes in Japan was a complex composed of the conidial states of A. vanbreuseghemii and the other asexual strains corresponding to T. interdigitale and a small number of the granulosum-asteroides form of which mating type was indeterminate. None of the isolates mated successfully with A. simii and A. benhamiae. Forty-nine isolates which successfully mated with A. vanbreuseghemii were further subclassified into 39 of the granulosum-asteroides form, three of the “powdery” form and seven of the “persicolor” form on the basis of the morphological differences in culture. The former one form was zoophilic in nature, while the latter two appeared anthropophilic in nature. These three forms differed from each other in their sexual reactivity. The granulosum-asteroides form consisted of “+” (80%) and “-” (20%) mating types, while the “powdery” form, the “persicolor” form and T. interdigitale were all of the “+” mating type. Differences in geographic distribution between “+” and “-” mating types were also elucidated for an epidemiological approach to this species complex.