THE DIVERSITY OF MALASSEZIA YEASTS CONFIRMED BY RIBOSOMAL-RNA SEQUENCE AND NUCLEAR-DNA COMPARISONS

One hundred and four Malassezia strains (52 isolated from humans and 52 from animals) were compared using large subunit (LSU) ribosomal RNA sequence similarity and nuclear DNA complementarity. Eight groups of strains were recognized as genetically distinct species. Each taxon was confirmed by a homogeneous mole % GC and percentages of DNA/DNA reassociations higher than 85%. The non-lipid-dependent Malassezia yeasts were maintained as the unique taxon M.pachydermatis. In contrast, lipid-dependent strains were shown to be distributed among seven species: M. furfur; M. sympodialis and M. species 1-5. These taxa matched remarkably well with morphological and serological differences documented by previous investigators. The LSU rRNA sequences allowed a further intraspecific resolution with most of genomic taxa represented by several closely related sequences: M. pachydermatis counted up to seven sequences, M. furfur four sequences, M. species 1 comprised three sequences and M. species 2 and M. species 5 two sequences. Three species, M. sympodialis, M. species 3 and M, species 4, displayed a unique type of sequence. Thus, the present report demonstrates the usefulness of sequencing for both taxonomic and epidemiological purposes.