Isolation, identification and characterization of yeasts from unexplored environments

Description of the research

An increasing number of studies demonstrated that microorganisms represent the most relevant biodiversity existing on Earth. Microorganisms colonize all ecological niches and are essential for maintaining terrestrial ecosystems. The importance of studying microbial biodiversity has been recognized at the international level through numerous research programs aimed at investigating and conserving microbial germplasm, both in situ and ex situ.

Although about 150,000 fungal species have been described up to now (of which 2,000 belong to yeast species), it has been calculated that these correspond to less than 7% of the estimated number of fungal species. Considering the frequency with which new yeast species are described, it is possible to hypothesize that between 300 and 500 years will be necessary to document all the existing biodiversity of this group of microorganisms.

Unexplored environments (e.g. marine, tropical, glacial, etc.) represent ecological niches whose microbial diversity is so far little explored. In particular, recent studies have highlighted that permanently cold environments (which represent one of the largest terrestrial biospheres, e.g. deep oceans, Arctic and Antarctic regions, mountain glaciers, etc.) can be colonized by a large diversity of psychrophilic microorganisms. It has also been verified that these ecosystems represent one of the most undersampled habitats in the Earth. They are destined in part to disappear due to global warming. Furthermore, the cold-adapted microbial populations colonizing these niches constitute an important part of biodiversity adapted to low temperatures which plays an essential role in biogeochemical cycles and in the mineralization of organic matter.

Therefore, one of the missions of the DBVPG Collection is represented by the isolation, identification and characterization of Non-Conventional Yeasts (NCY) from glacial environments such as Antarctica, Arctic regions, Andes and Alps. Thanks to the various sampling campaigns in Italy and abroad, and to the work of cultivation and isolation carried out in the DBVPG laboratory, it was possible to include in the Collection over 1,000 new psychrophilic (both obligate and facultative) strains belonging to 138 species and 57 different genera.

It is now universally accepted that the classification of yeasts requires a polyphasic approach including the study of cell morphology and physiology, followed by identification obtained through the use of one or more molecular techniques (sequencing of ribosomal DNA – D1 / D2 domain of the 26S rRNA gene or Internal Transcribed Spacers – ITS region 1&2, including the 5.8S gene or other target regions).

Following this approach all isolated strains were identified and new species and genera were also found.

Peer-reviewed international scientific papers

In recent years, researchers of the Department of Agricultural, Food and Environmental Sciences of the University of Perugia (hosting Institution of the DBVPG Collection) have contributed to the description of several new (never described before) genera and species, reported in peer-reviewed international scientific papers:

  • Mrakia robertii Thomas-Hall & Turchetti sp. nov.;
  • Holtermanniella Libkind, Wuczkowski, Turchetti & Boekhout gen. nov.;
  • Holtermanniella takashimae Wuczkowski, Passoth, Andersson, Turchetti, Prillinger, Boekhout & Libkind sp. nov.;
  • Glaciozyma Turchetti, Connell, Thomas-Hall & Boekhout gen. nov.;
  • Glaciozyma martinii Turchetti, Connell, Thomas-Hall & Boekhout sp. nov.;
  • Glaciozyma watsonii Thomas-Hall, Connell, Boekhout & Turchetti sp. nov.;
  • Candida molendinolei Čadež, Turchetti & Péter sp. nov.;
  • Taphrina antarctica Selbmann & Turchetti sp. nov.;
  • Naganishia vaughanmartiniae (Turchetti, Blanchette & Arenz) Yurkov sp. nov;
  • Naganishia onofrii (Turchetti, Selbmann & Zucconi) Yurkov sp. nov.;
  • Dioszegia patagonica Trochine, Turchetti, Vaz, Brandao, Rosa, Buzzini & Libkind sp. nov;
  • Cystobasidium alpinum Turchetti, Selbmann, Onofri & Buzzini sp. nov.;
  • Vustinia Kachalkin, Turchetti & Yurkov gen. nov.;
  • Vustinia terrea Kachalkin, Turchetti & Yurkov sp. nov.;
  • Kwoniella fici Turchetti & Buzzini sp. nov.;
  • Heterocephalacria gelida Turchetti & Kachalkin sp. nov.;
  • Piskurozyma silvicultrix Turchetti, Mašínová, Baldrian & Yurkov sp. nov.;
  • Naganishia nivalis Turchetti & Buzzini sp. nov.;
  • Mrakia fibulata Yurkov & Turchetti sp. nov.;
  • Mrakia stelviica Turchetti & Buzzini sp. nov.;
  • Mrakia montana Turchetti & Buzzini sp. nov.

Papers published on the subject in the last 5 years

K.L. Boundy-Mills, E. Glantschnig, I.N. Roberts, A. Yurkov, S. Casaregola, H.-M. Daniel, M. Groenewald, B. Turchetti (2016). Yeast culture collections in the twenty-first century: new opportunities and challenges. Yeast 33:243–260; DOI: 10.1002/yea.3171.

L. França, C. Sannino, B. Turchetti, P. Buzzini, R. Margesin (2016) Seasonal and altitudinal changes of culturable bacterial and yeast diversity in Alpine forest soils. Extremophiles 20:855–873; DOI: 10.1007/s00792-016-0874-2.

L. Mokhtarnejad, M. Arzanlou, A. Babai-Ahari, S. Di Mauro, A. Onofri, P. Buzzini, B. Turchetti (2016) Characterization of basidiomycetous yeasts in hypersaline soils of the Urmia Lake National Park Iran. Extremophiles 20:915–928; DOI: 10.1007/s00792-016-0883-1.

A. Trochine, B. Turchetti, A.B. Vaz, L. Brandao, L. Rosa, P. Buzzini, C. Rosa, D. Libkind (2017) Description of Dioszegia patagonica sp. nov., a novel carotenogenic yeast isolated from cold environments. International Journal of Systematic and Evolutionary Microbiology 67(11):4332-4339; DOI: 10.1099/ijsem.0.002211.

B. Turchetti, L. Selbmann, N. Gunde-Cimerman, P. Buzzini, J.P. Sampaio, P. Zalar (2018). Cystobasidium alpinum sp. nov. and Rhodosporidiobolus oreadorum sp. nov. from European Cold Environments and Arctic Region. Life 8(2):9; DOI: 10.3390/life8020009.

A. V. Kachalkin, B. Turchetti, J. Inácio, C. Carvalho, T. Mašínová, A. Pontes, O. Röhl, A. M. Glushakova, A. Akulov, P. Baldrian, D. Begerow, P. Buzzini, J. P. Sampaio, A. M. Yurkov (2019) Rare and undersampled dimorphic basidiomycetes. Mycological Progress 18:945–971; DOI: 10.1007/s11557-019-01491-5.

A. M. Yurkov, C. Sannino, B. Turchetti (2019) Mrakia fibulata sp. nov., a psychrotolerant yeast from temperate and cold habitats. Antonie van Leeuwenhoek, 113(4):499-510; DOI:10.1007/s10482-019-01359-4.

L. De Vero 1, M.B. Boniotti, M. Budroni, P. Buzzini, S. Cassanelli, R. Comunian, M. Gullo, A.F. Logrieco, I. Mannazzu, R. Musumeci, I. Perugini, G. Perrone, A. Pulvirenti, P. Romano, B. Turchetti, G.C. Varese (2019) Preservation, Characterization and Exploitation of Microbial Biodiversity: The Perspective of the Italian Network of Culture Collections. Microorganisms. 7,685; DOI: 10.3390/microorganisms7120685.

A.-H. Li, F.-X. Yuan, M. Groenewald, K. Bensch, A.M. Yurkov, K. Li, P.-J. Han, L.-D. Guo, M.C. Aime, J.P. Sampaio, S. Jindamorakot, B. Turchetti, J. Inacio, B. Fungsin, Q.-M. Wang, F.-Y. Bai (2020) Diversity and phylogeny of basidiomycetous yeasts from plant leaves and soil: Proposal of two new orders, three new families, eight new genera and one hundred and seven new species. Studies in Mycology 96:17-140; DOI: 10.1016/j.simyco.2020.01.002.

G. Verkley, G. Perrone, M. Pina, A.H. Scholz, J. Overmann, A. Zuzuarregui, I. Perugini, B. Turchetti, M. Hendrickx, G. Stacey, S. Law, J. Russell, D. Smith, N. Lima (2020). New ECCO model documents for Material Deposit and Transfer Agreements in compliance with the Nagoya Protocol. FEMS Microbiology Letters, 367(5), fnaa044; DOI: 10.1093/femsle/fnaa044.

B. Turchetti, C. Sannino, A. Mezzasoma, L. Zucconi, S. Onofri, P. Buzzini (2020). Mrakia stelviica sp. nov. and Mrakia montana sp. nov., two novel basidiomycetous yeast species isolated from cold environments. International Journal of Systematic and Evolutionary Microbiology 70(8), 4704-4713; DOI: 10.1099/ijsem.0.004336.

A. Yurkov, A. Alves, F-Y Bai, K. Boundy-Mills, P. Buzzini, N. Čadež, ……, B. Turchetti, Q-M Wang, T. Boekhout (2021) Nomenclatural issues concerning cultured yeasts and other fungi: why it is important to avoid unneeded name changes. IMA Fungus 12:18; DOI: 10.1186/s43008-021-00067-x.

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