Molecular Phylogenetics of Exophiala Species Isolated from Korea

BACKGROUND Recently, identification of fungi have been supplemented by molecular tools, such as ribosomal internal transcribed spacer (ITS) sequence analysis. According to these tools, morphological Exophiala species was newly introduced or redefined. OBJECTIVE This study was designed to investigate the phylogenetics based on ribosomal ITS sequence analysis from clinical Exophiala species isolated in Korea. METHODS The strains of Exophiala species were 4 clinical isolates of phaeohyphomycosis agents kept in the department of dermatology, Dongguk University Medical Center(DUMC), Gyeongju, Korea. The DNAs of total 5 strains of Exophiala species were extracted by bead-beating method. Polymerase chain reaction of ITS region using the primer pairs ITS1-ITS4, was done and phylogenetic tree contributed from sequences of ITS region from 5 Korean isolates including E. dermatitidis CBS 109154 and comparative related strains deposited in GenBank. RESULTS The strains of Exophiala species were 3 strains of E. dermatitidis, 1 strain of E. jeanselmei and 1 strain of Exophiala new species. Among the 3 subtypes (type A, B, C) of E. jeanselmei, E. jeanselmei DUMC 9901 belonged to type B. Of the 2 main types of E. dermatitidis (type A, B) and 3 subtypes of E. dermatitidis type A (A0, A1 and A2), two strains (E. dermatitidis CBS 709.95, E. dermatitidis CBS 109154) belonged to A0 subtypes, 1 strain (E. dermatitidis DUMC 9902) A1 subtype, respectively. CONCLUSION Phylogenetic analysis of ITS region sequence provided useful information not only for new species identification but for the subtyping and origin of Exophiala species.