ABSTRACT
The internal transcribed spacer 1 (ITS1) sequences of the nuclear rRNA gene (approximately 200 bp) of 33 strains of the Exophiala dermatitidis complex were determined; two similar species were added for comparison. A core group (I), including the type strain CBS 207. 35, contained 20 identical strains which had previously been found to have introns in their small sub-unit (SSU) rDNA. Eleven remaining strains identified as E. dermatitidis (groups II-V) differed from the core group in 1-4 nucleotide positions (plus a deletion in one strain); most of them lacked introns in their SSU ribosomal genes. The type strain of the meristematic species Sarcinomyces phaeomuriformis CBS 131.88 was found to differ significantly from E. dermatitidis. One strain had the annellidic morphology of E. dermatitidis, but the ITS1 sequence of S. phaeomuriformis. Strain CBS 709.95, an E. dermatitidis reported to have a meristematic synanamorph, was found to have ITS1 identity to the type strain of E. dermatitidis, although SSU sequences established previously suggested a close relationship with S. phaeomuriformis. Slight physiological differences were found between E. dermatitidis and S. phaeomuriformis. An oligonucleotide probe specific for E. dermatitidis was designed, thus able to discriminate this species from closely related black yeasts.
Subject(s)
DNA, Ribosomal/genetics , Exophiala/genetics , Mitosporic Fungi/genetics , RNA, Ribosomal, 5.8S/genetics , Base Sequence , DNA, Fungal/genetics , Exophiala/classification , Exophiala/physiology , Mitosporic Fungi/classification , Mitosporic Fungi/physiology , Molecular Sequence Data , Phylogeny , RNA, Fungal/genetics , Restriction Mapping , Sequence Alignment , Sequence Homology, Nucleic Acid , Species SpecificityABSTRACT
A new meristematic black yeast species, Sarcinomyces petricola, is described. All strains known to date were isolated from sun-exposed marble in the Mediterranean basin. On the basis of PCR-ribotyping and nutritional physiology, the species is classified as an anamorph member of the ascomycete family Herpotrichiellaceae (Chaetothyriales).
Subject(s)
Yeasts/classification , Culture Media/metabolism , DNA, Fungal/analysis , Environmental Microbiology , Fermentation , Mediterranean Region , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Yeasts/isolation & purification , Yeasts/metabolismABSTRACT
Taxonomic markers for differentiation of the anamorph genera Aureobasidium, Hormonema and Kabatiella were developed using PCR-ribotyping with the primers 5.8S-R and LR7 for amplification and the restriction enzymes Alul, Ddel, Hhal, Mspl and Rsal for digestion. Aureobasidium and Hormonema are optimally differentiated with Mspl; Ddel is particularly useful to distinguish Aureobasidium, Kabatiella and Selenophoma. Relationships of the anamorph genera Aureobasidium, Hormonema and Kabatiella with the teleomorph genera Pringsheimia and Dothiora are discussed.
Subject(s)
Classification , DNA, Ribosomal/genetics , Fungi/genetics , DNA/chemistry , DNA/genetics , DNA Primers , DNA Restriction Enzymes/metabolism , DNA, Ribosomal/classification , Electrophoresis, Agar Gel , Genetic Markers , Multigene Family/genetics , Phylogeny , Polymerase Chain Reaction , Polymorphism, Restriction Fragment LengthABSTRACT
The nuclear small subunit rRNA genes of authentic strains of the black yeasts Exophiala dermatitidis, Wangiella dermatitidis, Sarcinomyces phaemuriformis, Capronia mansonii, Nadsoniella nigra var. hesuelica, Phaeoannellomyces elegans, Phaeococcomyces exophialae, Exophiala jeanselmei var. jeanselmei and E. castellanii were amplified by PCR and directly sequenced. A putative secondary structure of the nuclear small subunit rRNA of Exophiala dermatitidis was predicted from the sequence data. Alignment with corresponding sequences from Neurospora crassa and Aureobasidium pullulans was performed and a phylogenetic tree was constructed using the neighbor-joining method. The obtained topology of the tree was confirmed by bootstrap analysis. Based upon this analysis all fungi studied formed a well-supported monophyletic group clustering as a sister group to one group of the Plectomycetes (Trichocomaceae and Onygenales). The analysis confirmed the close relationship postulated between Exophiala dermatitidis, Wangiella dermatitidis and Sarcinomyces phaeomuriformis. This monophyletic clade also contains the telemorph species Capronia mansonii thus confirming the concept of a teleomorph connection of the genus Exophiala to a member of the herpotrichiellaceae. However, Exophiala castellanii did not belong to this clade. Therefore, this species is not the anamorph of Capronia mansonii as it was postulated.
Subject(s)
Fungi/classification , Phylogeny , RNA, Fungal/genetics , RNA, Ribosomal/genetics , Ascomycota/genetics , Base Sequence , Exophiala/classification , Exophiala/genetics , Fungi/genetics , Molecular Sequence Data , Nucleic Acid Conformation , RNA, Fungal/chemistry , RNA, Ribosomal/chemistry , Sequence Analysis, DNAABSTRACT
Portion of the ribosomal repeat of the type strains of the genera Exophiala and Phaeococcomyces were subjected to RFLP analysis. The amplicon length of the small subunit rRNA, the fragment NS1-NS24, was found to vary between 1800 to 3200 nucleotides. In contrast, the length of the fragment ITS1-ITS4 comprising the internal transcribed spacers (ITS1 and ITS2) was found to be constant at 600 nucleotides. Analysis of restriction profiles confirmed the synonymy of Exophiala dermatitidis and Mycotorula schawaii. Torula bergeri and Sporotrichum gougerotii were found to be identical to Phaeoannellomyces elegans, but different from their alleged synonym E. castellanii. A phenogram is presented.
Subject(s)
Exophiala/genetics , Mitosporic Fungi/genetics , RNA, Fungal/genetics , RNA, Ribosomal/genetics , DNA, Ribosomal/genetics , Exophiala/classification , Mitosporic Fungi/classification , Phylogeny , Polymerase Chain Reaction/methods , Polymorphism, Restriction Fragment Length , Sequence Analysis, DNAABSTRACT
Nutritional physiological and tolerance tests were performed for all type strains of species currently classified in the black yeast genera Exophiala and Phaeococcomyces, including some additional type strains of taxa recently reidentified as Exophiala species. Most described Exophiala species can be distinguished by physiological characters. Exophiala jeanselmei with its varieties, and E. castellanii should all be retained as separate taxa. The pairs of strains Mycotorula schawii/Exophiala dermatitidis, Hormodendrum negronii/Exophiala jeanselmei var. lecaniicorni and Sporotrichum gougerotii/Torulabergeri were found to be conspecific. Phenetic analyses of physiological data support the identity of Phaeococcomyces exophialae as a yeast-like synanamorph of Exophiala spinifera. The taxonomic positions of the genera Nadsoniella, Phaeoannellomyces and Wangiella are discussed. The genera Exophiala and Phaeococcomyces are unrelated.
Subject(s)
Exophiala/physiology , Mitosporic Fungi/physiology , Exophiala/classification , Mitosporic Fungi/classification , Phylogeny , Species SpecificityABSTRACT
The black yeast Hortaea werneckii is known to be a causative agent of human tinea nigra but is also found in the environment. Strains from dissimilar sources were studied by polymerase chain reaction fingerprinting of nuclear DNA, using primers annealing to repetitive and random sequences. The seven groups found correspond to those known from restriction fragment length polymorphism (RFLP) studies of the mitochondrial DNA of the same strains. Two main groups contained strains from human as well as from non-human sources. The human strains did not cluster, but were randomly distributed over several populations. It was concluded that these strains are not pathogenic. The factor common to both niches is a relatively high salt concentration.
Subject(s)
Tinea/microbiology , Yeasts/classification , Air Microbiology , Animals , Base Sequence , DNA Fingerprinting/methods , DNA, Fungal/genetics , Genotype , Humans , Molecular Sequence Data , Plants/microbiology , Polymerase Chain Reaction , Yeasts/geneticsABSTRACT
Strains of Exophiala dermatitidis, mainly originating from patients with systemic neurotropic mycosis in Asia and from the lungs of patients with cystic fibrosis (CF) in Europe, were analysed by ribotyping of the small subunit rDNA and by random amplification of polymorphic DNA (RAPD). A characteristic banding pattern for the species was found after restriction analysis of amplified fragments V9 and ITS4. The small subunit rDNA gene of five strains was about 1800 base pairs (bp) long, while in 16 strains its length was about 3000 bp. Using RAPD, seven populations could be distinguished. European CF strains as well as Asian strains from systemic mycoses are mainly distributed over two populations, one of which contained both CF strains and a systemic strain. It is concluded that the two clinical pictures are caused by genetically similar strains. The differences in pathogenicity may be explained by immunological differences in the hosts or by differences in exposure to the fungal propagules.
Subject(s)
Exophiala/pathogenicity , Mycoses/etiology , Base Sequence , DNA Primers/genetics , DNA, Fungal/genetics , DNA, Ribosomal/genetics , Exophiala/classification , Exophiala/genetics , Humans , Molecular Sequence Data , Mycoses/microbiology , Polymerase Chain ReactionABSTRACT
Characters of morphology and nutritional physiology of Exophiala jeanselmei var. lecanii-corni are described. The taxon was proven to be distinct from the var. jeanselmei and from Exophiala dermatitidis by physiology, which is supported by molecular characters. A case of cutaneous phaeohyphomycosis caused by var. lecanii-corni is reported.
