Leucosporidium drummii sp. nov., a member of the Microbotryomycetes isolated from soil

A Deep Insight into the Diversity of Microfungal Communities in Arctic and Antarctic Lakes

We assessed fungal diversity in water and sediment samples obtained from five Arctic lakes in Ny-Ålesund (Svalbard Islands, High Arctic) and five Antarctic lakes on Livingston and Deception Islands (South Shetland Islands), using DNA metabarcoding. A total of 1,639,074 fungal DNA reads were detected and assigned to 5980 ASVs amplicon sequence variants (ASVs), with only 102 (1.7%) that were shared between the two Polar regions. For Arctic lakes, unknown fungal taxa dominated the sequence assemblages, suggesting the dominance of possibly undescribed fungi. The phylum Chytridiomycota was the most represented in the majority of Arctic and Antarctic samples, followed by Rozellomycota, Ascomycota, Basidiomycota, and the less frequent Monoblepharomycota, Aphelidiomycota, Mortierellomycota, Mucoromycota, and Neocallimastigomycota. At the genus level, the most abundant genera included psychrotolerant and cosmopolitan cold-adapted fungi including Alternaria, Cladosporium, Cadophora, Ulvella (Ascomycota), Leucosporidium, Vishniacozyma (Basidiomycota), and Betamyces (Chytridiomycota). The assemblages displayed high diversity and richness. The assigned diversity was composed mainly of taxa recognized as saprophytic fungi, followed by pathogenic and symbiotic fungi.

First Speleomycological Study on the Occurrence of Psychrophilic and Psychrotolerant Aeromycota in the Brestovská Cave (Western Tatras Mts., Slovakia) and First Reports for Some Species at Underground Sites

Most underground ecosystems are heterotrophic, fungi in these objects are dispersed in the air in the form of spores, and they may be potentially hazardous to mammals. Research in underground sites has focused on mesophilic airborne fungi and only a few concerned cold-adapted species. Therefore, the goal of our research was the first report of psychrophilic and psychrotolerant aeromycota in the Brestovská Cave using culture-based techniques with genetic and phenotypic identification. Plates with PDA medium containing sampled biological material were incubated at 8 ± 0.5 °C. The density of mycobiota inside the cave ranged from 37.4 to 71 CFU 1 m-3 of air and 63.3 CFU 1 m-3 of air outside the cave. Thus, the level of fungal spores did not exceed the standards for the mycological quality of the air. A total of 18 species were isolated during the study, and some species may be potentially dangerous to people with weakened immune system. All fungal species were present inside the cave and only seven of them were outside. Cladosporium cladosporioides dominated in the external air samples and Mortierella parvispora was cultured most frequently from internal air samples. To our knowledge, this is the first discovery of the fungal species such as Coniothyrium pyrinum, Cystobasidium laryngis, Filobasidium wieringae, Leucosporidium drummii, M. parvispora, Mrakia blollopis, Nakazawaea holstii, and Vishniacozyma victoriae in the air inside the underground sites. Moreover, C. pyrinum, C. laryngis, L. drummii, M. blollopis, and N. holstii have never been detected in any component of the underground ecosystems. There are possible reasons explaining the detection of those species, but global warming is the most likely.

Associations between dog keeping and indoor dust microbiota

Living with dogs appears to protect against allergic diseases and airway infections, an effect possibly linked with immunomodulation by microbial exposures associated with dogs. The aim of this study was to characterize the influence of dog ownership on house dust microbiota composition. The bacterial and fungal microbiota was characterized with Illumina MiSeq sequencing from floor dust samples collected from homes in a Finnish rural-suburban (LUKAS2, N = 182) birth cohort, and the results were replicated in a German urban (LISA, N = 284) birth cohort. Human associated bacteria variable was created by summing up the relative abundances of five bacterial taxa. Bacterial richness, Shannon index and the relative abundances of seven bacterial genera, mostly within the phyla Proteobacteria and Firmicutes, were significantly higher in the dog than in the non-dog homes, whereas the relative abundance of human associated bacteria was lower. The results were largely replicated in LISA. Fungal microbiota richness and abundance of Leucosporidiella genus were higher in dog homes in LUKAS2 and the latter association replicated in LISA. Our study confirms that dog ownership is reproducibly associated with increased bacterial richness and diversity in house dust and identifies specific dog ownership-associated genera. Dogs appeared to have more limited influence on the fungal than bacterial indoor microbiota.

The establishment of a fungal consortium in a new winery

The biodiversity and evolution of fungal communities were monitored over a period of 3 vintages in a new winery. Samples were collected before grape receipt and 3 months after fermentation from 3 different wine related environments (WRE): floor, walls and equipment and analyzed using Illumina Mi-Seq. Genera of mold and filamentous fungi (294), non-enological (10) and wine-associated yeasts (25) were detected on all WREs before the arrival of the first harvest. Among them, genera like Alternaria and Aureobasidium persisted during two vintages. Therefore, these genera are not specific to winery environment and appear to be adapted to natural or anthropic environments due to their ubiquitous character. Some genera like Candida were also detected before the first harvest but only on one WREs, whereas, on the other WREs they were found after the harvest. The ubiquitous character and phenotypic traits of these fungal genera can explain their dynamics. After the first harvest and during 3 vintages the initial consortium was enriched by oenological genera like Starmerella introduced either by harvest or by potential transfers between the different WREs. However, these establishing genera, including Saccharomyces, do not appear to persist due to their low adaptation to the stressful conditions of winery environment.

Yeasts from macroalgae and lichens that inhabit the South Shetland Islands, Antarctica

Antarctic terrestrial ecosystems are largely dominated by lichens, while shallow coastal environments are mainly covered by macroalgae. The aim of this study was to isolate and to evaluate the diversity of yeasts in different species of macroalgae and lichens collected in South Shetland Islands, Antarctica. A total of 405 yeasts were recovered (205 from macroalgae and 200 from lichens). The yeast community from macroalgae was most diversity than the yeast community from lichen. The dominance index was similar for both substrates. A total of 24 taxa from macroalgae and 18 from lichens were identified, and only 5 were common to both substrates. Metschnikowia australis, Mrakia sp., Rhodotorula glacialis and Glaciozyma litorale were the most abundant yeasts in macroalgae and Cryptococcus victoriae, Rhodotorula laryngis, Rhodotorula arctica, Trichosporon sp. 1 and Mrakia sp. were the most abundant in lichens. Based on molecular and phylogenetic analyses, four yeast from macroalgae and six from lichens were considered potential new species. This is the first study to report the yeast communities from the Antarctic macroalgae Himantothallus grandifolius and lichen Ramalina terebrata. Results suggest that Antarctic phyco and lichensphere represent a huge substrate for cold-adapted yeasts and enhanced the knowledge of the microbiota from extreme environments.

Phylogeny of yeasts and related filamentous fungi within Pucciniomycotina determined from multigene sequence analyses

In addition to rusts, the subphylum Pucciniomycotina (Basidiomycota) includes a large number of unicellular or dimorphic fungi which are usually studied as yeasts. Ribosomal DNA sequence analyses have shown that the current taxonomic system of the pucciniomycetous yeasts which is based on phenotypic criteria is not concordant with the molecular phylogeny and many genera are polyphyletic. Here we inferred the molecular phylogeny of 184 pucciniomycetous yeast species and related filamentous fungi using maximum likelihood, maximum parsimony and Bayesian inference analyses based on the sequences of seven genes, including the small subunit ribosomal DNA (rDNA), the large subunit rDNA D1/D2 domains, the internal transcribed spacer regions (ITS 1 and 2) of rDNA including the 5.8S rDNA gene; the nuclear protein-coding genes of the two subunits of DNA polymerase II (RPB1 and RPB2) and the translation elongation factor 1-α (TEF1); and the mitochondrial gene cytochrome b (CYTB). A total of 33 monophyletic clades and 18 single species lineages were recognised among the pucciniomycetous yeasts employed, which belonged to four major lineages corresponding to Agaricostilbomycetes, Cystobasidiomycetes, Microbotryomycetes and Mixiomycetes. These lineages remained independent from the classes Atractiellomycetes, Classiculomycetes, Pucciniomycetes and Tritirachiomycetes formed by filamentous taxa in Pucciniomycotina. An updated taxonomic system of pucciniomycetous yeasts implementing the 'One fungus = One name' principle will be proposed based on the phylogenetic framework presented here.

Sex in the cold: taxonomic reorganization of psychrotolerant yeasts in the order Leucosporidiales

Species of Leucosporidiales are a group of psychrotolerant yeasts with biotechnological potential. In the present work, we studied the phenotypic, genetic and sexual characteristics of three species of this genus (Leucosporidium scottii, Leucosporidiella creatinivora and Le. yakutica) to clarify the evolutionary relationship among these closely related taxa. From the results obtained, it becomes clear that these yeasts can interbreed. Although genetic delimitation is possible for the three species, the extent of nucleotide substitutions and phenotypic differences observed between them are lower than that expected for species that have ended the speciation process. Our taxonomic conclusion is to maintain the three taxa until further genomic data are gathered. However, the concept of L. scottii species complex is proposed for this group of species. Finally, we transfer all Leucosporidiella and Mastigobasidium species to Leucosporidium (Leucosporidiales), and, in order to end the polyphyly condition of these taxa, we propose the new genus Pseudoleucosporidium gen. nov. and the new combination Peudoleucosporidium fasciculatum comb. nov.

Leucosporidium escuderoi f.a., sp. nov., a basidiomycetous yeast associated with an Antarctic marine sponge

A basidiomycetous yeast, strain E2A-C3-II, was isolated from a marine sponge (Hymeniacidon sp.) collected at a depth of 6 m in Fildes Bay, King George Island, Antarctica. The phylogenetic analysis revealed that the yeast isolated is related to Leucosporidium drummii, Leucosporidiella muscorum and to the Leucosporidium scottii group, including Leucosporidiella creatinivora and Leucosporidiella yakutica. The analysis of the nucleotide differences and the genetic distances of the D1/D2 domain of the LSU rDNA gene and 5.8S ITS regions support that strain E2A-C3-II represents a new species. The novel species can be distinguished from L. drummii by its ability to assimilate L-sorbose, L-rhamnose, lactose and ribitol. The maximum temperature for growth was 25 °C. On the basis of morphological, biochemical and physiological characterization, and phylogenetic and nucleotide analysis, a novel basidiomycetous yeast species, Leucosporidium escuderoi f.a., sp. nov., is proposed. The type strain is E2A-C3-II(T) (=CBS 12734(T) =CECT 13080(T)). The Mycobank ( http://www.mycobank.org ) accession number is MB 804654. The nucleotide sequences of D1/D2 domain of the LSU rDNA gene and 5.8S-ITS regions obtained in this work have been deposited in Genbank under the Accession numbers JN181009 and JN197600, respectively.