Sequence diversity of the intergenic spacer region of the rRNA gene of Malassezia globosa colonizing the skin of patients with atopic dermatitis and healthy individuals

Abstract

The lipophilic yeast Malassezia globosa is one of the major constituents of the mycoflora of the skin of patients with atopic dermatitis (AD). We compared the genotypes of M. globosa colonizing the skin surface of 32 AD patients and 20 healthy individuals for polymorphism of the intergenic spacer (IGS) 1 region of the rRNA gene. Sequence analysis demonstrated that M. globosa was divided into four major groups, which corresponded to the sources of the samples, on the phylogenetic tree. Of the four groups, two were from AD patients and one was from healthy subjects. The remaining group included samples from both AD patients and healthy subjects. In addition, the IGS 1 region of M. globosa contained short sequence repeats: (CT)(n), and (GT)(n). The number of sequence repeats also differed between the IGS 1 of M. globosa from AD patients and that from healthy subjects. These findings suggest that a specific genotype of M. globosa may play a significant role in AD, although M. globosa commonly colonizes both AD patients and healthy subjects.

FIG. 1.

Schematic representation of the rRNA gene in the type strain (CBS 7966) of M. globosa.

FIG. 2.

Alignment of the DNA sequences of the IGS 1 region of M. globosa CBS 7966 and CBS 8745.

FIG. 3.

Distribution of SSRs in the IGS 1 region of the M. globosa rRNA gene. Solid bars, M. globosa obtained from AD patients; open bars, M. globosa obtained from healthy subjects.

FIG. 4.

Phylogenetic tree of M. globosa colonizing the skin surface of AD patients and healthy subjects based on DNA sequences of the IGS 1 region. AD, patient with atopic dermatitis; HS, healthy subject. The numbers show the confidence level from 100 replicate bootstrap samplings (frequencies of <50% are not shown). Knuc, Kimura's parameter (10).