Fungalpedia – Note 3296, Saccharomycetes

 

Saccharomycetes G. Winter, Rabenh. Krypt.-Fl. Ed. 2, 1(1): 32, 68. (1884) emend. M. Groenew., Hittinger, Opulente & A. Rokas, Stud. Mycol. 105: 13 (2023).

Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.

Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1n-t.

Classification: Saccharomycotina, Ascomycota, Dikarya, Fungi.

Notes: The class Saccharomycetes was introduced by Winter (1884) for single-celled “plants” that multiply by budding and form endogen spores. Eriksson and Winka (1997) also proposed Saccharomycetes to accommodate the order Saccharomycetales, but it is a later homonym of Winter’s class. Until recently Saccharomycetes has comprised all (more than 1,200) species assigned to Saccharomycotina. Detailed treatments of the species assigned to Saccharomycetes were presented in the subsequent editions of The Yeasts: A Taxonomic Study (Lodder and Kreger-van Rij 1952; Lodder 1970; Kreger-van Rij 1984; Kurtzman and Fell 1998; Kurtzman et al. 2011). Kurtzman was among the first to apply DNA sequence-based classification for Saccharomycetes. Initially, he utilized rRNA coding gene sequences (Kurtzman and Robnett 1997, 1998), and later conducted multigene phylogenetic studies (Kurtzman 2003; Kurtzman and Robnett 2003, 2007, 2010; Kurtzman et al. 2007, 2008; Kurtzman and Suzuki 2010; Kurtzman and Robnett 2013a, b). In the latest decade, the classification of yeasts, including ascomycete, especially at higher ranks, has increasingly relied on genome-scale phylogenetic reconstructions (Hittinger et al. 2015; Shen et al. 2016, 2018, 2020). Based on relative evolutionary divergence (RED) analyses, Li et al. (2021a) pointed out that the subphylum Saccharomycotina is under-classified. Groenewald et al. (2023) proposed a new genome-informed higher-rank classification for Saccharomycotina. They emended the diagnosis of class Saccharomycetes, and reassigned numerous taxa from Saccharomycetes to six newly erected classes; Alloascoideomycetes, Dipodascomycetes, Lipomycetes, Pichiomycetes, Sporopachydermiomycetes and Trigonopsidomycetes. They also introduced new order(s) in each class. All classes and orders were supported by taxon-specific orthologous groups of proteins (OGs), used as diagnoses of the taxa. As summarised by Daniel et al. (2014), according to phylogenetic studies, numerous Candida species outside the Lodderomyces/Candida clade are affiliated with the class Saccharomycetes (sensu Groenewald et al. 2023). Some of them, (e.g. C. glabrata) have already been transferred to the corresponding teleomorph genera (Takashima and Sugita 2022), while others, (e.g. C. adriatica) are still awaiting reassignment.

According to Groenewald et al. (2023), the class currently comprises four orders; Ascoideales, Phaffomycetales, Saccharomycetales and Saccharomycodales, accommodating six families and 31 genera. The order Ascoideales comprises taxa forming expanding mycelia, while budding cells are present or absent. Phaffomycetales and Saccharomycetales are characterised by yeast cells multiplying by multilateral budding, while Saccharomycodales cells multiply by bipolar budding.

Type order: Saccharomycetales C. Luerssen, Grundz. Bot.: 156. 1877, emend. M. Groenew., Hittinger, Opulente & A. Rokas, Stud. Mycol. 105: 14 (2023).

Type family: Saccharomycetaceae C. Luerssen, Grundz. Bot.: 160. (1877).

Type genus: Saccharomyces Meyen, Arch. Naturgesch. 4 (2): 100. (1838).

Type species: Saccharomyces cerevisiae (Desm.) Meyen, Arch. Naturgesch. 4 (2): 100. (1838).

Other accepted species: Species Fungorum – search Saccharomycetes.

 

Figure 1 – Microscopic features of taxa in Saccharomycotina. a Septate non-sporulating hyphae and pseudohyphae of Alloascoidea hylecoeti (Alloascoideaceae, Alloascoideales, Alloascoideomycetes). b-d Alloascoidea africana (Alloascoideaceae, Alloascoideales, Alloascoideomycetes) asci with ascospores and released ascospores (indicated with arrows). e,f Dipodascus albidus (Dipodascaceae, Dipodascales, Dipodascomycetes). e. Ascospores within hyphae and released ascospores. f Hyphae, arthroconidia and ascospores (indicated by arrow). g Lipomyces starkeyi (Lipomycetaceae, Lipomycetales, Lipomycetes) conjugation between a cell and its bud, ascus with ellipsoidal ascospores (indicated by arrows). h-j Pichia membranifaciens (Pichiaceae, Pichiales, Pichiomycetes) budding cells and asci with hat-shaped ascospores (indicated by arrows). k Pachysolen tannophilus (Pachysolenaceae, Alaninales, Pichiomycetes) budding cells, ascus with ascospores and liberated ascospores (indicated by arrow). l,m Metschnikowia bicuspidata (Metschnikowiaceae, Serinales, Pichiomycetes). (l) M. bucuspidata var. californica budding cells and needle-shaped ascospores. (m) M. bucuspidata var. chathamia budding cells and needle-shaped ascospores. n Saccharomyces cerevisiae (Saccharomycetaceae, Saccharomycetales, Saccharomycetes) budding cells and unconjugated, persistent ascus with globose ascospores (indicated by arrow). o, p Phaffomyces opuntiae (Phaffomycetaceae, Phaffomycetales, Saccharomycetes). (o) Budding cells and asci with hat-shaped ascospores (indicated by arrows). (p) Budding cells in short chains and asci with hat-shaped ascospores (indicated by arrows). q Saccharomycodes ludwigii (Saccharomycodaceae, Saccharomycodales, Saccharomycetes) bipolar cell division of budding cells and asci with spherical ascospores (indicated by arrows). r-t Ascoidea rubescens (Ascoideaceae, Ascoideales, Saccharomycetes). (r) Asexual cells and cluster of ascospores (indicated by arrow) (s) Asexual cells and septate hyphae, (t) Ascus with spores in different states of nascendi. u Sporopachydermia lactativora (Sporopachydermiaceae, Sporopachydermiales, Sporopachydermiomycetes) budding cells. v Trigonopsis variabilis (Trigonopsidaceae, Trigonopsidales, Trigonopsidomycetes). Budding cells with ellipsoidal and triangular morphology. Triangular cells produce ellipsoidal and triangular buds. Scale bar: a = 5μm, b-q, u,v = 10μm, r-t =30μm.

 

References

Daniel HM, Lachance MA, Kurtzman CP. 2014 – On the reclassification of species assigned to Candida and other anamorphic ascomycetous yeast genera based on phylogenetic circumscription. Antonie van Leeuwenhoek 106:67–84.

Eriksson OE, Winka W. 1997 – Supraordinal taxa of Ascomycota. Myconet. 1:1–16.

Groenewald M, Hittinger CT, Bensch K, Opulente DA et al. 2023 – A genome-informed higher rank classification of the biotechnologically important fungal subphylum Saccharomycotina. Stud Mycol 105:1–22.

Hittinger CT, Rokas A, Bai FY, Boekhout T et al. 2015 – Genomics and the making of yeast biodiversity. Curr Opin Genet Dev 35:100–109.

Kreger-van Rij NJW. 1984 – The yeasts – A taxonomic study, 3rd edn. Elsevier, Amsterdam.

Kurtzman CP, Fell JW, Boekhout T. 2011 – The yeasts – A taxonomic study, 2, 5th edn. Elsevier, Amsterdam.

Kurtzman CP, Fell JW. 1998 – The yeasts – a taxonomic study, 4th edn. Elsevier, Amsterdam.

Kurtzman CP, Robnett CJ, Basehoar-Powers E. 2008 – Phylogenetic relationships among species of Pichia, Issatchenkia and Williopsis determined from multigene phylogenetic analysis, and the proposal of Barnettozyma gen. nov., Lindnera gen. nov. and Wickerhamomyces gen. nov. FEMS Yeast Res 8:939–954. 

Kurtzman CP, Robnett CJ. 1997 – Identification of clinical important ascomycetous yeasts based on nucleotide divergence in the 5’end of the large-subunit (26S) ribosomal DNA gene. J Clin Microbiol 35:1216–1223.

Kurtzman CP, Robnett CJ. 1998 – Identification and phylogeny of ascomycetous yeasts from analyses of nuclear large subunit (26S) ribosomal DNA partial sequences. Antonie van Leeuwenhoek 73:331-371. 

Kurtzman CP, Robnett CJ. 2003 – Phylogenetic relationships among yeasts of the “Saccharomyces complex” determined from multigene sequence analyses. FEMS Yeast Res 3:417–432.

Kurtzman CP, Robnett CJ. 2007 – Multigene phylogenetic analysis of the Trichomonascus, Wickerhamiella and Zygoascus yeast clades, and the proposal of Sugiyamaella gen.nov. and 14 new species combinations. FEMS Yeast Res 7:141–151.

Kurtzman CP, Robnett CJ. 2010 – Systematics of methanol assimilating yeasts and neighboring taxa from multigene sequence analysis and the proposal of Peterozyma gen. nov. FEMS Yeast Res 10:353–361.

Kurtzman CP, Robnett CJ. 2013a – Alloascoidea hylecoeti gen. nov., comb. nov., Alloascoidea africana comb. nov., Ascoidea tarda sp. nov., and Nadsonia starkeyi-henricii comb. nov., new members of the Saccharomycotina (Ascomycota). FEMS Yeast Res 13:423–432. 

Kurtzman CP, Robnett CJ. 2013b – Relationships among genera of the Saccharomycotina (Ascomycota) from multigene phylogenetic analysis of type species. FEMS Yeast Res 13:23–33. 

Kurtzman CP. 2003 – Phylogenetic circumscription of Saccharomyces, Kluyveromyces and other members of the Saccharomycetaceae, and the proposal of the new genera Lachancea, Nakaseomyces, Naumovia, Vanderwaltozyma and Zygotorulaspora. FEMS Yeast Res 4:233–245.

Li Y, Steenwyk JL, Chang Y, Wang Y et al. 2021a – A genome-scale phylogeny of fungi. Curr Biol 31:1653–1665.

Lodder J, Kreger-van Rij NJW. 1952 – The yeasts – A taxonomic study, 1st edn. Elsevier, Amsterdam.

Lodder J. 1970 – The yeasts – A taxonomic study, 2nd ed. Elsevier, Amsterdam.

Shen XX, Opulente DA, Kominek J, Zhou XF et al. 2018 – Tempo and mode of genome evolution in the budding yeast subphylum. Cell 175:1533–1545.

Shen XX, Steenwyk JL, LaBella AL, Opulente DA et al. 2020 – Genome-scale phylogeny and contrasting modes of genome evolution in the fungal phylum Ascomycota. Sci Adv 6:eabd0079.

Shen XX, Zhou X, Kominek J, Kurtzman CP et al. 2016 – Reconstructing the backbone of the Saccharomycotina yeast phylogeny using genome-scale data. G3 6:3927–3939.

 

Entry by

Nalin N. Wijayawardene, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, P.R. China, Tropical Microbiology Research Foundation, 96/N/10, Meemanagoda Road, 10230 Pannipitiya, Sri Lanka, Department of Bioprocess Technology, Faculty of Technology, Rajarata University, Sri Lanka

 

Published online 25 September 2026

 

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