Molecular Phylogenetics of the Genus Trichosporon Inferred from Mitochondrial Cytochrome b Gene Sequences

Abstract

Trichosporon Behrend is a member of the basidiomycetous yeasts. The species of the genus are causative agents of the superficial to deep-seated mycosis known as trichosporonosis. Generally, it is found that trichosporonosis is caused by six species: Trichosporon asahii, Trichosporon asteroides, Trichosporon cutaneum, Trichosporon inkin, Trichosporon mucoides, and Trichosporon ovoides (16,19,36,37). It is also found that the major causative agents of trichosporonosis differ in causing infection. T. asahii and T. mucoides are involved in deep-seated infection. T. asteroides and T. cutaneum are associated with superficial infection. T. ovoides and T. inkin are involved in white piedra of the head and genital area, respectively. Trichosporon pullulans is not a major causative agent of trichosporonosis and is rarely isolated from fungemia patients (25,26). Recent studies indicate that the number of patients with illness caused by a Trichosporon species has been increasing (21,22,42,43,52,56). Deep-seated trichosporonosis has a high mortality rate, and the prognosis for patients is very poor. Trichosporon species are also responsible for summer-type hypersensitivity pneumonitis (1, 2, 34, 55).The genus Trichosporon was revised using a combination of physiological and molecular criteria (14, 15). Subsequently, Sugita et al. (35,36,38) contributed significantly to the classification and taxonomic position of the genus Trichosporon. Recently, the number of species of the genus Trichosporon has expanded from 19 (17) to 23 (13). All of these classifications are based on the analysis of different regions of the rRNA genes, such as 5S rRNA genes, 26S rRNA genes, 18S rRNA genes, the D1/D2 region of large-subunit rRNA genes, or the internal transcribed spacer region of rRNA genes. There is a need for further evidence based on different DNA sequences to establish phylogenetic relationships (27). It was therefore of interest to find the relationships among various species of Trichosporon by analyzing mitochondrial (mt) DNA rather than rRNA genes.Mitochondrial genes are an attractive marker for inferring the phylogeny of closely related species because of the rapid evolution of the mitochondrial genome, the lack of recombination, and the strict maternal inheritance (29). Restriction fragment length polymorphism analysis of mt DNA has been shown to be useful for estimating the relationships among fungi (18,24,44). The mt cytochrome b (cyt b) gene has been used to study the evolution and phylogenetic relationships of many animals, including birds, mammals, and fish (3,9,10,12,20,23), but the sequence of this gene had been determined for only six species of fungi before our study (46). We have reported that the mt cyt b gene is useful for the identification, classification, and phylogenetic analysis of fungi (4-7, 46-49, 53, 54).We have previously shown that the cyt b gene phylogeny of basidiomycetous yeasts correlates with the cell wall biochemistry and septal ultrastructure (5). However, only two species of Trichosporon, T. aquat...

Molecular phylogeny of basidiomycetous yeasts in theCryptococcus luteoluslineage (Tremellales) based on nuclear rRNA and mitochondrial cytochromebgene sequence analyses: proposal ofDerxomycesgen. nov. andHannaellagen. nov., and description of eight novelDerxomycesspecies

“…The distinction of the C. luteolus lineage that was strongly supported (84% bootstrap value) was confirmed. Among the mitochondrial genes, cytochrome b (cyt b) has been used successfully in the phylogenetic analyses of basidiomycetous yeasts (Biswas et al, 2001(Biswas et al, , 2003(Biswas et al, , 2005Yokoyama, 2005). Bullera anomala formed a basal branch within the B. mrakii clade (see the supplementary material).…”

“…Because of its uniparental inheritance, haploid status and a relatively high rate of evolution, the mitochondrial genome has been an attractive target for exploring genetic markers to infer the phylogeny of various organisms. Among the mitochondrial genes, cytochrome b (cyt b) has been used successfully in the phylogenetic analyses of basidiomycetous yeasts (Biswas et al, 2001(Biswas et al, , 2003(Biswas et al, , 2005Yokoyama, 2005). In the present study, partial sequences of the cyt b gene (386 bp in length) of the species in the C. luteolus lineage and of selected species from closely related lineages or clades were determined.…”

Current Knowledge of Trichosporon spp. and Trichosporonosis

“…Using this approach, two isolates were then identified: Trichosporon sp. strain CBS 5581 was identified as T. pullulans, and the clinical isolate IFM 48794 was identified as T. faecale (20).…”

“…Biswas et al (20) analyzed the sequences of the mitochondrial cytochrome b (cyt b) genes from 23 different fungal strains representing 42 species. They amplified a 396-bp fragment and observed that there were 141 variable nucleotide sites (35.6%) among Trichosporon strains.…”

Decolorization of Azo Dyes by Yeasts

“…Recently, some interesting coupled systems, advanced oxidation processes (AOPs)-biological agents (cells or enzymes), have been proposed to treat various types of industrial wastewaters. Textile, pulp and paper, surfactants, explosives from military industries, phenolic-rich agro-industrial effluents, and Fell et al [46] c Biswas et al [47] pesticides contaminated effluents are some examples of wastewaters treated with combined processes. It can be said that the use of AOPs in conjunction with biological oxidation has been a recent innovation in the treatment strategies for wastewater.…”