Diversity, ecology and systematics of yeast fungi

PI: Dr. Andrey Yurkov

DSMZ has a rare expertise in the field of yeast ecology and systematics. The present research is directed towards the isolation of yeasts from soils, plant material and aquatic habitats.

Yeasts represent a unique life form of fungi propagating through budding. Many yeasts grow as predominantly unicellular organisms but some are switching to filamentous growth characteristic for other fungi. Yeasts are well known as the fermentative agent in wine and beer. Furthermore, they are industrially relevant producers of organic acids, enzymes, proteins, lipids, and pigments. However, unlike a few biotechnological-relevant species and model organisms, including the baker’s yeast Saccharomyces cerevisiae, other species do have habitats in nature. Soil yeasts have been studied in Germany and Portugal in several research projects. These studies yielded more than 100 yeasts, including species and genera that are new to science. Description of these species is ongoing. Since it involves a detailed investigation of closely related species, the work results in taxonomic rearrangements in this group of fungi. Additionally, a few follow-up studies will investigate properties of these yeasts, including enzymatic capabilities and growth responses.

Recent changes in yeast systematics have been directed towards harmonization of the taxonomy of filamentous and yeast-like fungi. A comprehensive phylogenetic classification framework was proposed to update the classification of yeasts and closely related filamentous taxa, considering also the implementation of the “One Fungus = One Name” nomenclatural principle, which was adapted by the International Code of Nomenclature for algae, fungi, and plants (ICN) in Melbourne. This activity is coordinated by several scientific bodies where DSMZ is also represented: the International Commission on Yeasts (ICY) of IUMS, International Commission on Taxonomy of Fungi (ICTF) of IUMS and International Mycological Association (IMA).

Further work is direct to obtain material and sequence data for undersampled lineages (rare taxa) and to find molecular markers providing better phylogenetic resolution. An additional related both to the systematics and evolutionary biology topic is speciation and species boundaries in basidiomycetous fungi. This question is studied in yeasts using a combination of multi-locus sequence typing, analyses of MAT loci, mating experiments and whole-genome sequencing. DSMZ is involved in several cooperation projects exploring the evolution of mating genes and speciation in Tremellomycetes.

Physiological capabilities of nectar yeasts and their interactions with pollinators will be investigated in a joint project funded by the DAAD PPP Joint Research program. The overall goal of the project is to enhance our understanding of the role that nectar-borne yeasts play in pollination of seed plants. Pollination ecology is among the major topics in environmental sciences these days. The decline of wild- and honey bees is of an extraordinary relevance for mankind, and consequences of this decline are constantly discussed in the society. Pollinators decline is a global threat to agriculture and economy and has been recognized by the United Nations, i.e. the International Pollinator Initiative within Convention on Biological Diversity and FAO’s Global Action on Pollination Services for Sustainable Agriculture. Experiments performed in this project will elucidate chemical alterations of the nectar habitat and evaluate the importance of yeasts in the floral system for insect nutrition, reward and distraction. This cooperation project between Italian and German partners includes experts in the fields of yeast physiology, nectar chemistry and metabolomics.

Selected references

  1. Liu XZ, Wang QM, Göker M, Groenewald M, Kachalkin AV, Lumbsch HT, Millanes AM, Wedin M, Yurkov AM, Boekhout T, Bai FY (2015). Towards an integrated phylogenetic classification of the Tremellomycetes. Studies in Mycology, 81, 85-147.
  2. Yurkov AM, Wehde T, Federici J, Schäfer AM, Ebinghaus M, Lotze-Engelhard S, Mittelbach M, Prior R, Richter, Röhl, O, Begerow, D (2016). Yeast diversity and species recovery rates from beech forest soils. Mycological Progress, 15, 845-859.
  3. Yurkov AM, Röhl O, Pontes A, Carvalho C, Maldonado C, Sampaio JP (2016). Local climatic conditions constrain soil yeast diversity patterns in Mediterranean forests, woodlands and scrub biome. FEMS Yeast Research, 16, fov103.