Basidioascus and Geminibasidium: a new lineage of heat-resistant and xerotolerant basidiomycetes

Abstract

Using a heat-treatment method, two genera of heat-resistant and xerotolerant basidiomycetes were isolated from soil samples. These two genera, Basidioascus and Geminibasidium gen. nov., are morphologically similar and phylogenetically related. The genus Basidioascus originally was described as an ascomycete, but the structures originally interpreted as single-spored asci appear to represent basidiospores. Morphologically both genera are characterized by the lack of a fruiting body, conspicuously granular and deciduous basidia with a unique basal lateral projection and apparently double-walled basidiospores. The basidia, rather than the basidiospores, are forcibly discharged in Basidioascus species but not in Geminibasidium species. In Geminibasidium species a putative basidium arises from a primary cell. These are novel forms of basidia ontogenesis previously unseen in basidiomycetes. The rDNA (SSU + 5.8S + LSU) Bayesian phylogenetic analysis suggests that these fungi are distantly related to Wallemia, another xerotolerant basidiomycete genus commonly found in indoor air dust, dried foods and natural hypersaline environments. Given the physiological similarity and phylogenetic relationships, Basidioascus and Geminibasidium are classified in a new order, Geminibasidiales, and are taxonomically assigned to the class Wallemiomycetes. Based on morphological observations and molecular phylogeny of the internal transcribed spacer (ITS), two species of Basidioascus (B. undulatus, B. magus sp. nov.) and two species of Geminibasidium (G. donsium sp. nov., G. hirsutum sp. nov.) are described. A key to these species is provided using micromorphological and cultural characters.

Yeast diversity and species recovery rates from beech forest soils

“…from Cystofilobasidiales. However, LSU rRNA and SSU rRNA sequences showed low similarity to Cystofilobasidiales (data not shown) but rather to the genus Basidioascus (Nguyen et al 2013). Analysis of the concatenated dataset SSU rRNA and LSU rRNA dataset confirmed the placement of this strain in Wallemiomycetes (Fig.…”

“…6) and is distantly related to the genera Basidioascus, Geminibasidium (Nguyen et al 2013) and Wallemia. …”

Expanding evolutionary diversity in the Ustilaginomycotina: Fereydouniaceae fam. nov. and Fereydounia gen. nov., the first urocystidalean yeast lineage

“…Two isolates that formed similar colonies were selected for further examination. To assess colony morphology and sizes, the isolates were grown on YPG agar, 2 % malt extract agar (MEA, Merck, Germany), dichloran 18 % glycerol agar (DG18, Merck, Germany) and malt yeast 40 % sucrose agar (M40Y) (Nguyen et al 2013). Microscopic observations were carried out on the yeast cells grown on cornmeal agar (CMA) and YPG agar.…”

Xerotolerant fungi in house dust: taxonomy of Spiromastix, Pseudospiromastix and Sigleria gen. nov. in Spiromastigaceae (Onygenales, Eurotiomycetes)

“…1100 bp of the 59 end of the 18S gene and ca. 1000 bp of the 28S gene followed the protocols of Nguyen et al (2013). PCR success was confirmed by agarose gel electrophoresis.…”