A Taxonomic Revision of the Wallemia sebi Species Complex

PLoS One. 2015 May 27;10(5):e0125933. doi: 10.1371/journal.pone.0125933. eCollection 2015.

Abstract

Wallemia sebi is a xerophilic food- and air-borne fungus. The name has been used for strains that prevail in cold, temperate and tropical climates. In this study, multi-locus phylogenetic analyses, using the internal transcribed spacer (ITS) regions, DNA replication licensing factor (MCM7), pre-rRNA processing protein (TSR1), RNA polymerase II largest subunit (RPB1), RNA polymerase II second largest subunit (RPB2) and a new marker 3´-phosphoadenosine-5´-phosphatase (HAL2), confirmed the previous hypothesis that W. sebi presents a complex of at least four species. Here, we confirm and apply the phylogenetic analyses based species hypotheses from a companion study to guide phenotypic assessment of W. sebi like strains from a wide range of substrates, climates and continents allowed the recognition of W. sebi sensu stricto and three new species described as W. mellicola, W. Canadensis, and W. tropicalis. The species differ in their conidial size, xerotolerance, halotolerance, chaotolerance, growth temperature regimes, extracellular enzyme activity profiles, and secondary metabolite patterns. A key to all currently accepted Wallemia species is provided that allow their identification on the basis of physiological, micromorphological and culture characters.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ascomycota / classification*
  • Ascomycota / isolation & purification
  • Ascomycota / pathogenicity
  • Ascomycota / physiology*
  • Ecosystem
  • Enzymes / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Humans
  • Livestock / microbiology
  • Minichromosome Maintenance Complex Component 7 / genetics
  • Nucleotidases / genetics
  • Phylogeny*
  • Secondary Metabolism
  • Skin / microbiology
  • Spores, Fungal / physiology

Substances

  • Enzymes
  • Fungal Proteins
  • Nucleotidases
  • Minichromosome Maintenance Complex Component 7

Grants and funding

This work was funded by the Slovenian Research Agency (https://www.arrs.gov.si/en/dobrodoslica.asp) through the Infrastructural Centre Mycosmo (http://www.ex-genebank.com/) and the Young Researcher Grant to SJ, 1000-11-310102. This work was partly funded by Slovenian Ministry of Higher Education, Science and Technology (http://www.arhiv.mvzt.gov.si/en/) and European Regional Development Fund through the Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CIPKeBiP, http://cipkebip.org/, OP13.1.1.2.02.0005), and by grants to KAS and HDTN from the Alfred P. Sloan Foundation Program on the Microbiology of the Built Environment (http://www.sloan.org/major-program-areas/). Parts of this work were realized within the frame of FP7 Project CropSustaIn (FP7-REGPOT-CT2012-316205). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.