Nomenclatural issues concerning cultured yeasts and other fungi: why it is important to avoid unneeded name changes

Abstract

The unambiguous application of fungal names is important to communicate scientific findings. Names are critical for (clinical) diagnostics, legal compliance, and regulatory controls, such as biosafety, food security, quarantine regulations, and industrial applications. Consequently, the stability of the taxonomic system and the traceability of nomenclatural changes is crucial for a broad range of users and taxonomists. The unambiguous application of names is assured by the preservation of nomenclatural history and the physical organisms representing a name. Fungi are extremely diverse in terms of ecology, lifestyle, and methods of study. Predominantly unicellular fungi known as yeasts are usually investigated as living cultures. Methods to characterize yeasts include physiological (growth) tests and experiments to induce a sexual morph; both methods require viable cultures. Thus, the preservation and availability of viable reference cultures are important, and cultures representing reference material are cited in species descriptions. Historical surveys revealed drawbacks and inconsistencies between past practices and modern requirements as stated in the International Code of Nomenclature for Algae, Fungi, and Plants (ICNafp). Improper typification of yeasts is a common problem, resulting in a large number invalid yeast species names. With this opinion letter, we address the problem that culturable microorganisms, notably some fungi and algae, require specific provisions under the ICNafp. We use yeasts as a prominent example of fungi known from cultures. But viable type material is important not only for yeasts, but also for other cultivable Fungi that are characterized by particular morphological structures (a specific type of spores), growth properties, and secondary metabolites. We summarize potential proposals which, in our opinion, will improve the stability of fungal names, in particular by protecting those names for which the reference material can be traced back to the original isolate.

Trends in yeast diversity discovery

“…Many countries, biomes and habitats have not been explored in depth or are not studied at all. Even though DNA-metabarcoding studies have the power to document a vast diversity of yeasts in e.g., soils, air and seawater, and also may provide insights in the extent on yet unknown species, it is still needed to obtain living species to describe them (Lücking et al 2021;Yurkov et al 2021). This is not only because current nomenclatural practices demand a physical specimen as the type, a practice that may or may not change in the future, but also because living isolates may boost knowledge on biotechnological, biomedical, agricultural, and food-fermentation applications, which in turn may benefit economically under-developed regions of the world that may harbor a rich yeasts diversity.…”

Taxonomic Revision of the pulcherrima Clade of Metschnikowia (Fungi): Merger of Species

“…However, at least 30 other species concepts have been described in the literature [19]. Those preferably applied to fungi have been critically reviewed in numerous recent works (e.g., [20][21][22]). One of these concepts is the biological concept which defines a species as a group of interbreeding natural populations that are reproductively isolated from other such groups [23].…”

A re-assessment of Taxomyces andreanae, the alleged taxol-producing fungus, using comparative genomics

“…The current case, where a culture of the type material has been deposited in a public domain collection from where it can be obtained later on for genome sequencing, is also a very good example for the validity of the approach by Yurkov et al ( 2021 ). Among others, these authors have emphasized the need to use living cultures as type material in the future.…”