Malassezia arunalokei sp. nov., a Novel Yeast Species Isolated from Seborrheic Dermatitis Patients and Healthy Individuals from India

Abstract

The majority of species within the genus Malassezia are lipophilic yeasts that colonize the skin of warm-blooded animals. Two species, Malassezia globosa and Malassezia restricta, are implicated in the causation of seborrheic dermatitis/dandruff (SD/D). During our survey of SD/D cases, we isolated several species of Malassezia and noticed vast variations within a few lipid-dependent species. Variations observed in the phenotypic characteristics (colony morphology, absence of catalase activity, growth at 37°C, and precipitation surrounding wells containing Tween 20 or Cremophor EL) suggested the possible presence of a novel species. Sequence divergence observed in the internal transcribed spacer (ITS) region, the D1/D2 domain, and the intergenic spacer 1 (IGS1) region of rDNA and the TEF1 gene, PCR-restriction fragment length polymorphism (RFLP) analysis of the ITS2 region, and fluorescent amplified fragment length polymorphism analysis support the existence of a novel species. Based on phenotypic and molecular characterization of these strains, we propose a new species, namely, M. arunalokei sp. nov., and we designate NCCPF 127130 (= MTCC 12054 = CBS 13387) as the type strain.

FIG 1

Phenotypic characteristics differentiating M. arunalokei sp. nov. from the closely related species M. restricta. (a and b) Colonies of M. arunalokei sp. nov. (CBS 13387^T) (a) and M. restricta (CBS 7877^T) (b) cultured on modified Dixon's agar at 34°C. (c and d) Scanning electron microscopic images of M. arunalokei sp. nov. (CBS 13387^T) (c) and M. restricta (CBS 7877^T) (d) cells. (e and f) Tween 20, 40, 60, and 80 and Cremophor EL (Cr EL) assimilation by M. arunalokei sp. nov. (CBS 13387^T) (e) and M. restricta (CBS 7877^T) (f).

FIG 2

Phylogenetic relationships of M. arunalokei sp. nov. and 14 recognized Malassezia spp. The phylograms of the presently known Malassezia spp. were inferred using the neighbor-joining method. The maximum composite likelihood model was used to compute evolutionary distances. The trees are drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic trees (1,000 bootstrap replicates). (a and b) Phylograms of Malassezia spp. based on the D1/D2 regions of 26S rDNA (a) and ITS-5.8S rDNA (b), using Cryptococcus neoformans CBS 132^T as an outgroup. (c) Phylogram of M. arunalokei sp. nov. and M. restricta strains based on the IGS1 region, using M. globosa CBS 7996^T as an outgroup. (d) Phylograms of Malassezia spp. based on the TEF1 gene, using Trichosporon coremiiforme CBS 2482 as an outgroup.

FIG 3

FAFLP banding patterns of five representative M. arunalokei sp. nov. strains and presently known Malassezia spp. Fragments in the range of 40 to 350 bp were included in the analysis. Bars, percentages of similarity. The strains of M. arunalokei sp. nov. showed 80% similarity among themselves, but the M. restricta isolates showed only 25% similarity to the M. arunalokei sp. nov. isolates.