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The use of non-conventional brewing yeasts as alternative starters is a very promising approach which received increasing attention from worldwide scientists and brewers. Despite the feasible application of non-conventional yeasts in brewing processes, their regulations and safety assessment by the European Food Safety Authority still represent a bottlenecked hampering their commercial release, at least into EU market. Thus, research on yeast physiology, accurate taxonomic species identification and safety concerns associated with the use of non-conventional yeasts in food chains is needed to develop novel healthier and safer beers. Currently, most of the documented brewing applications catalysed by non-conventional yeasts are associated to ascomycetous yeasts, while little is known about analogous uses of basidiomycetous taxa. Therefore, in order to extend the phenotypic diversity of basidiomycetous brewing yeasts the aim of this investigation is to check the fermentation aptitudes of thirteen Mrakia species in relation to their taxonomic position within the genus Mrakia. The volatile profile, ethanol content and sugar consumption were compared with that produced by a commercial starter for low alcohol beers, namely Saccharomycodes ludwigii WSL 17. The phylogeny of Mrakia genus showed three clusters that clearly exhibited different fermentation aptitudes. Members of M. gelida cluster showed a superior aptitude to produce ethanol, higher alcohols, esters and sugars conversion compared to the members of M. cryoconiti and M. aquatica clusters. Among M. gelida cluster, the strain M. blollopis DBVPG 4974 exhibited a medium flocculation profile, a high tolerance to ethanol and to iso-α-acids, and a considerable production of lactic and acetic acids, and glycerol. In addition, an inverse relationship between fermentative performances and incubation temperature is also displayed by this strain. Possible speculations on the association between the cold adaptation exhibited by M. blollopis DBVPG 4974 and the release of ethanol in the intracellular matrix and in the bordering environment are presented., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

The fungal mycelium represents the essence of the fungal lifestyle, and understanding how a mycelium is constructed is of fundamental importance in fungal biology and ecology. Previous studies have examined initial developmental patterns or focused on a few strains, often mutants of model species, and frequently grown under non-harmonized growth conditions; these factors currently collectively hamper systematic insights into rules of mycelium architecture. To address this, we here use a broader suite of fungi (31 species including members of the Ascomycota, Basidiomycota and Mucoromycota), all isolated from the same soil, and tested for ten architectural traits under standardized laboratory conditions. We find great variability in traits among the saprobic fungal species, and detect several clear tradeoffs in mycelial architecture, for example between internodal length and hyphal diameter. Within the constraints so identified, we document otherwise great versatility in mycelium architecture in this set of fungi, and there was no evidence of trait 'syndromes' as might be expected. Our results point to an important dimension of fungal properties with likely consequences for coexistence within local communities, as well as for functional complementarity (e.g. decomposition, soil aggregation).

The present work studied novel basidiomycetous yeasts from maize and northern wild rice plants. From comparisons of ribosomal internal transcribed spacer region (ITS) and large subunit (LSU) (D1 and D2 domains), and subsequent phylogenetic analyses, the following species were resolved and described: Papiliotrema zeae Yurkov & Kurtzman sp. nov. (ex-type cultures DSM 104035, NRRL Y-63980, MB 827356, GenBank MH718306), Solicoccozyma zizaniae Yurkov & Kurtzman sp. nov. (ex-type cultures DSM 104031, NRRL Y-7649, MB 827354, GenBank MH718302) and Vishniacozyma kurtzmanii Yurkov sp. nov. (ex-type cultures DSM 104032, NRRL Y-63981, MB 827355, GenBank MH718303). A search among environmental sequences showed that all three yeasts were previously detected, but not reliably assigned to a genus or clade. Papiliotrema zeae from maize and S. zizaniae from northern wild rice were previously found in agricultural soils under maize and rice, respectively., (© FEMS 2019.)

In the course of an ongoing study aiming to catalogue the natural yeast biodiversity of Iran, a number of yeasts were isolated from plant material collected from mangrove forests on the shoreline of Qeshm Island. Two strains were identified as members of order Microstromatales. Standard phenotypic, biochemical, physiological characterization and a phylogenetic analyses of the combined 26S rRNA gene (D1/D2 domains) and ITS region sequences showed the conspecificity of these isolates and suggest their placement in the genus Jaminaea, close to Jaminaea lanaiensis and Jaminaea angkoriensis. Here, we describe this species as Jaminiaea pallidilutea sp. nov. with IBRC-M 30284 T =DSM 104392 T =CBS 14684 T as the type strain. The Mycobank accession number is MB 819618.

Yeast strains belonging to the basidiomycetous genus Cryptotrichosporon were isolated from forest soils in Serra da Arrábida Natural Park in Portugal. Similar to the already-known representatives of this genus, the new isolates formed pigmented colonies of a distinctive pale orange colour. Phylogenetic analyses employing concatenated sequences of the D1/D2 domains of the 26S (large subunit) rRNA gene and the internal transcribed spacer (ITS) region supported the recognition of three novel species: Cryptotrichosporon argae sp. nov. (type strain CM 19T=CBS 14376T=PYCC 7010T=DSM 104550T; MycoBank accession number MB 817168), Cryptotrichosporon brontae sp. nov. (type strain CM 1562T=CBS 14303T=PYCC 7011T=DSM 104551T; MycoBank accession number MB 817077) and Cryptotrichosporon steropae sp. nov. (type strain OR 395T=CBS 14302T=PYCC 7012T=DSM 104552T; MycoBank accession number MB 817078).

Two novel yeast species were isolated from the guts of two different termite species. A new member of the genus Sugiyamaella was isolated from the hindgut and nest material of the lower Australian termite Mastotermes darwiniensis. The second novel yeast species, isolated from the higher termite Odontotermes obesus, was identified as a member of the genus Papiliotrema. Both yeast species were able to hydrolyse xylan, methylumbelliferyl β-xylobiose and methylumbelliferyl β-xylotriose. The ability to debranch different hemicellulose side chains and growth without the addition of external vitamins was observed. A symbiotic role of the novel yeast species is indicated, especially in respect to xylan degradation and the production of vitamins. Here, we describe these species as Sugiyamaella mastotermitis sp. nov., MycoBank 816574 (type strain MD39VT=DSM 100793T=CBS 14182T), and Papiliotrema odontotermitis f.a., sp. nov., MycoBank 816575 (type strain OO5T=DSM 100791T=CBS 14181T). Additionally, we transfer Candida qingdaonensis to the genus Sugiyamaella and propose the following combination: Sugiyamaella qingdaonensis f.a., comb. nov., MycoBank 816576.

Understanding diversity and distribution patterns of fungi, including yeasts, ultimately depends on accuracy of species recognition. However, different approaches to yeast species recognition often result in different entities or operational taxonomic units. We studied the effects of using different yeast species recognition approaches, namely morphological species recognition (MSR) and phylogenetic species recognition (PSR), on the distribution patterns of widespread basidiomycetous yeasts. Hence, we have revised a collection of yeast fungi isolated from spatially remote birch forests in the Moscow Region and Western Siberia with molecular typing and identification tools. PCR fingerprinting and rDNA sequencing analyses of strains of nine species previously identified on the basis of morphological and physiological tests (MSR) yielded 21 phylogenetic species (PSR), including three currently undescribed taxa. The number of distinct phylogenetic species comprised within a single morphospecies ranged from one to seven. A total of ten species were found in both regions, whereas the distribution of 11 yeasts was restricted to a single region only. Both geographical region and type of substrate (plant or soil) influence yeast distribution. Cryptococcus wieringae, C. victoriae, C. magnus, and Leucosporidium scottii were frequently found on plant substrates, whereas C. terricola and C. podzolicus were associated to soil substrates. Occurrence of C. magnus, C. albidus and Sporobolomyces roseus was found to depend on the geographical region. Microsatellite-PCR fingerprinting, MSP-PCR, applied to studying yeast intraspecific variability revealed three different types of distribution: (a) variability that depends on geographical factors (Curvibasidium cygneicollum, C. podzolicus, C. victoriae), (b) genetic identity irrespectively of the region of isolation (Rhodotorula pinicola, C. terricola), and (c) high degree of genetic variability that did not correlate with region of sampling (C. albidus and C. magnus).

Background: Studies on the diversity of yeasts in floral nectar were first carried out in the late 19th century. A narrow group of fermenting, osmophilous ascomycetes were regarded as exclusive specialists able to populate this unique and species poor environment. More recently, it became apparent that microorganisms might play an important role in the process of plant pollination. Despite the importance of these nectar dwelling yeasts, knowledge of the factors that drive their diversity and species composition is scarce., Results: In this study, we linked the frequencies of yeast species in floral nectars from various host plants on the Canary Islands to nectar traits and flower visitors. We estimated the structuring impact of pollination syndromes (nectar volume, sugar concentration and sugar composition) on yeast diversity.The observed total yeast diversity was consistent with former studies, however, the present survey yielded additional basidiomycetous yeasts in unexpectedly high numbers. Our results show these basidiomycetes are significantly associated with ornithophilous flowers. Specialized ascomycetes inhabit sucrose-dominant nectars, but are surprisingly rare in nectar dominated by monosaccharides., Conclusions: There are two conclusions from this study: (i) a shift of floral visitors towards ornithophily alters the likelihood of yeast inoculation in flowers, and (ii) low concentrated hexose-dominant nectar promotes colonization of flowers by basidiomycetes. In the studied floral system, basidiomycete yeasts are acknowledged as regular members of nectar. This challenges the current understanding that nectar is an ecological niche solely occupied by ascomycetous yeasts.

Interactions between mushrooms, yeasts, and parasitic fungi are probably common in nature, but are rarely described. Bolete fruiting bodies are associated with a broad spectrum of microorganisms including yeasts, and they are commonly infected with filamentous mycoparasites of the genus Sepedonium (teleomorph Hypomyces). We report the isolation of 17 yeast strains from Paxillus and Xerocomus, 16 of which were obtained from the surface tissue, the primary site of Sepedonium infection. Phylogenetic analyses with the D1/D2 region of the 28S ribosomal gene and the internal transcribed spacers placed the yeasts as Rhodotorula, Rhodosporidium, and Mastigobasidium from the Pucciniomycotina, Cryptococcus, Cystofilobasidium, Holtermanniella, and Trichosporon from the Agaricomycotina, and Kluyveromyces from the Saccharomycotina including the first isolation of Rhodotorula graminis from Europe. To investigate the influence of the yeast strains on the mycoparasite and the host fungus, in vitro assays were conducted with Sepedonium chrysospermum and Paxillus involutus. Both S. chrysospermum growth inhibitory and stimulating yeast strains were detected among the isolates. The number of S. chrysospermum inhibitory yeast strains increased and the number of S. chrysospermum stimulatory yeast strains decreased in the presence of P. involutus in co-cultures. Low nutrient levels in the culture medium also led to an increased number of S. chrysospermum inhibitory yeast strains and ten yeasts inhibited the mycoparasite in spatial separation by a crosswall. Six yeast strains inhibited P. involutus in dual culture, and the inhibitory P. involutus yeast interactions increased to nine in the presence of S. chrysospermum. Our results suggest that the bolete-associated yeasts influence the growth of the mycoparasitic fungus, which may affect the health of the fruiting bodies.

Cryptococcus flavescens and C. terrestris are phenotypically indistinguishable sister species that belong to the order Tremellales (Tremellomycetes, Basidiomycota) and which may be mistaken for C. laurentii based on phenotype. Phylogenetic separation between C. flavescens and C. terrestris was based on rDNA sequence analyses, but very little is known on their intraspecific genetic variability or propensity for sexual reproduction. We studied 59 strains from different substrates and geographic locations, and used a multilocus sequencing (MLS) approach complemented with the sequencing of mating type (MAT) genes to assess genetic variation and reexamine the boundaries of the two species, as well as their sexual status. The following five loci were chosen for MLS: the rDNA ITS-LSU region, the rDNA IGS1 spacer, and fragments of the genes encoding the largest subunit of RNA polymerase II (RPB1), the translation elongation factor 1 alpha (TEF1) and the p21-activated protein kinase (STE20). Phylogenetic network analyses confirmed the genetic separation of the two species and revealed two additional cryptic species, for which the names Cryptococcus baii and C. ruineniae are proposed. Further analyses of the data revealed a high degree of genetic heterogeneity within C. flavescens as well as evidence for recombination between lineages detected for this species. Strains of C. terrestris displayed higher levels of similarity in all analysed genes and appear to make up a single recombining group. The two MAT genes (STE3 and SXI1/SXI2) sequenced for C. flavescens strains confirmed the potential for sexual reproduction and suggest the presence of a tetrapolar mating system with a biallelic pheromone/receptor locus and a multiallelic HD locus. In C. terrestris we could only sequence STE3, which revealed a biallelic P/R locus. In spite of the strong evidence for sexual recombination in the two species, attempts at mating compatible strains of both species on culture media were unsuccessful. [ABSTRACT FROM AUTHOR]

Anther smuts in the genus Microbotryum often show very high host specificity toward their caryophyllaceous hosts, but some of the larger host groups such as Dianthus are crucially undersampled for these parasites so that the question of host specificity cannot be answered conclusively. In this study we sequenced the internal transcribed spacer (ITS) region of members of the Microbotryum dianthorum species complex as well as their Dianthus hosts. We compared phylogenetic trees of these parasites including sequences of anther smuts from other Caryophyllaceae, mainly Silene, with phylogenies of Caryophyllaceae that are known to harbor anther smuts. Additionally we tested whether observed patterns in parasites are due to shared ancestry or if geographic separation is a factor that should be taken into consideration in delimitating species. Parasites on Dianthus showed mainly an arbitrary distribution on Dianthus hosts, whereas parasites on other Caryophyllaceae formed well-supported monophyletic clades that corresponded to restricted host groups. The same pattern was observed in the Caryophyllaceae studied: morphologically described Dianthus species did not correspond well with monophyletic clades based on molecular data, whereas other Caryophyllaceae mainly did. We suggest that these different patterns primarily result from different breeding systems and speciation times between different host groups as well as difficulties in species delimitations in the genus Dianthus. [ABSTRACT FROM AUTHOR]