Contributions to a revision of the genusTrichosporon

Abstract

The genus Trichosporon was revised using characters of morphology, ultrastructure, physiology, ubiquinone systems, mol% G + C of DNA, DNA/DNA reassociations and 26S ribosomal RNA partial sequences. A total of 101 strains was used, including all available type and authentic cultures of previously described taxa. Nineteen taxa could be distinguished, 15 of which having Q-9 coenzyme systems and 4 having Q-10. Sixteen previously described names were reduced to synonymy. One new species was described. The genus is characterized by the presence of arthroconidia. Few species possess further diagnostic morphological characters, such as the presence of appressoria, macroconidia or meristematic conidiation. The septa of two species were found to be non-perforate, while those of the remaining species contained dolipores at variable degrees of differentiation, with or without vesicular or tubular parenthesomes. All species were able to assimilate a large number of carbon compounds; visible CO2 production was absent. The genus was found to be fairly homogeneous on the basis of a phylogenetic analysis of partial 26S rRNA sequences, with the exception of T. pullulans which proved to be unrelated. Most taxa were found to occupy well-defined ecological niches. Within the group of taxa isolated from humans, a distinction could be made between those involved in systemic mycoses and those which mainly caused pubic or non-pubic white piedras, respectively. One species was consistently associated with animals, while others came mainly from soil or water. One species was mesophilic and another psychrophilic.

Phylogenetic and Taxonomic Heterogeneity of Cryptococcus humicolus by Analysis of the Sequences of the Internal Transcribed Spacer Regions and 18S rDNA, and the Phylogenetic Relationships of C. humicolus, C. curvatus, and the Genus Trichosporon

“…As for trichosporonosis, Trichosporon cutaneum (or T beigelii) has long been believed to be the causative agent of this infection. A 28S rDNA sequence analysis by Gueho et al (4) clearly revealed the intraspecific heterogeneity of this species. On the basis of this result, some authors subsequently demonstrated that the major causative agent of trichosporonosis differs in each type of infection (3,5,19,20).…”

Increased release of glucuronoxylomannan antigen and induced phenotypic changes in Trichosporon asahii by repeated passage in mice

“…beigelii (T. cutaneum) was initially reported as the causative agent of this disease. However, it was reclassified into 20 species by the molecular evolution classification system, based on DNA-DNA homology, introduced by Guého et al in 1992 [5]. According to the new classification, the species most often associated with deep-seated trichosporonosis are T. asahii and T. mucoides [6]; these are also the major causative agents of the summer-type of hypersensitivity pneumonitis.…”

Myococinogeny in the genus bullera: anti-tremellaceous yeast activity of killer toxin produced by bullera hannae.

“…Cryptococcus (Table 5), the species with highly similar values of the sequences (3,8,9,15) had the same response to the mycocin. This congruence between data on rRNA sequences and mycocin sensitivity suggest that the latter character reflects the phylogenetic relation between yeasts.…”