Polarized growth and cellular asymmetry are broadly conserved properties of fungal life, from transient bud-site selection in unicellular yeasts to sustained hyphal extension in filamentous and coenocytic species. While vesicle trafficking, cytoskeletal organization, and cell-wall remodeling are well-established contributors to these processes, the role of mRNA localization is only beginning to be fully appreciated. In this review, we examine how the spatial regulation of mRNAs and their translation contributes to fungal polarity, morphogenesis, and environmental adaptation. We discuss current knowledge around three interconnected layers contributing to mRNA localization: active cytoskeletal transport-actin-based in compact yeasts and microtubule-based in long hyphae; partitioning into biomolecular condensates such as P-bodies and Whi3-mRNA assemblies; and cytoplasmic-scale architectural features including bulk flow, nuclear positioning, and nuclear heterogeneity that become increasingly important in multinucleate and coenocytic systems such as arbuscular mycorrhizal fungi. Together, these mechanisms establish spatial gene expression as an integral component of fungal polarity, with implications for fungal development, host-pathogen interactions, and ecological adaptation, and for our broader understanding of polarized growth in eukaryotic cell organization.

Although most studies in the regulation of gene transcription in eukaryotes have focused on protein-coding genes transcribed into mRNA by RNA polymerase II, the regulation of RNA polymerase I (RNA Pol I) transcription is a key step in the cell's adaptation to environmental or physiological changes. This polymerase transcribes rRNA, a fundamental component of ribosomes that controls the translation of mRNAs into proteins-macromolecules that are both highly abundant and energetically costly to synthesize. Using the yeast Saccharomyces cerevisiae as a model, we have previously shown that adaptation of RNA Pol I synthesis rate (SR) to large changes in cell volume exhibited by some mutants, such as cln3, occurs over the long term through amplification of rDNA gene copies across several hundred cell divisions. However, it remains unclear what happens in the short term in de novo generated mutants that do not display rDNA amplification but exhibit all other phenotypic characteristics of the evolved cln3 mutant. Here, using an in vivo labeling procedure, we show that the RNA Pol I SR is similar in de novo and evolved cln3 mutants and that it seems not to be an alteration in the proportion of active rDNA copies or rRNA processing between both cln3 mutants. Finally, by measuring the ratio of active elongating RNA Pol I molecules to the total loaded onto rDNA genes, we conclude that short-term adaptation occurs through an increase in their transcription efficiency that compensates the decrease in the total number of elongating RNA polymerases.

Yeasts of the genus Yamadazyma have received increasing attention in the last decade due to the description of new species, their diverse ecological distribution and their biotechnological potential. The genus Yamadazyma was proposed in 1989, but was not accepted until 2005 due to its polyphyletic nature. Over the years, many new species have been described, and several Candida species have been reassigned to Yamadazyma. However, some Yamadazyma species remain unvalidated, and it is unclear whether the genus Keqinozyma is truly a distinct or should be included within Yamadazyma. Currently, the genus Yamadazyma formally includes 72 species. This genus is widely distributed across various environments worldwide, including aquatic habitats, phylloplane, insects, soil, food products, and humans. Although some species and phylogenetic groups exhibit recurring ecological and geographical patterns, such associations are not generally exclusive. Overall, the genus Yamadazyma appears to be ubiquitous. The presence of this genus across various habitats has facilitated studies on its biotechnological applications including cellobiose fermentation for second-generation bioethanol production and biosynthesis of value-added metabolites such as riboflavin. The genus Yamadazyma plays an active role in food production, contributing to product quality through enzymatic and antagonistic activities, while in agriculture it shows potential through biocontrol activity against phytopathogens. Recent descriptions of new species and the reclassification of previously classified Candida species have fragmented information on this genus. This review aims to address knowledge gaps regarding Yamadazyma by providing a comprehensive resource that unifies taxonomy, ecology, biotechnology, and pathogenesis to support further studies.

Cancer, one of the world's leading causes of death, is characterized by a complex metabolic reprogramming that features the Warburg effect as one of its hallmarks. The Warburg effect involves increased glucose and amino acid metabolism, which promotes tumor proliferation and progression. Although cancer has historically been attributed to genetic mutations, recent studies suggest a possible metabolic origin. However, a key characteristic of cancer cells is their greater adaptability than normal cells, as evidenced by their resistance to chemotherapy, which stems from their high mutability. This underscores the need to examine the relationship between metabolic reprogramming and cancer development from both metabolic and evolutionary perspectives. In this context, Saccharomyces cerevisiae snf1∆ strain has emerged as an ideal cellular model for studying the Warburg effect. This study aimed to determine whether deletion of the SNF1 gene in S. cerevisiae affects its chronological aging and competitiveness in a glucose and amino acid-dependent manner. Herein, we provide evidence that the snf1∆ strain changes the chronological aging depending on nutrimental condition, under low-nutrient levels shortens (0.1% glucose + 0.1× amino acids), and increases under high-nutrient levels (5% glucose + 3× amino acids). Competitiveness of the snf1∆ strain in cocultivation with wild-type was also improved in 5% glucose + 3× amino acids, by approximately two orders of magnitude. These results indicate that snf1∆ strain aging and competitiveness are also sensitive to nutrimental status, as was observed in cancer cells.

In this study, we sampled 26 larvae of the ground-nesting solitary bee Epicharis bicolor and isolated four candidate novel yeast species belonging to the genera Starmerella, Wickerhamiella, and Zygoascus, which were the most prevalent taxa. The bee E. bicolor collects floral oils from specialized oil-secreting glands, known as elaiophores, predominantly found in Malpighiaceae flowers. Based on sequencing of the ITS and D1/D2 regions of the rRNA gene as well as taxogenomic analyses, the novel yeast species are described here as Starmerella fernandosilveirae f.a., sp. nov. (CBS 19575; MycoBank MB864887), Zygoascus agrestis sp. nov. (CBS 19580; MycoBank MB864888), Zygoascus riopretensis f.a., sp. nov. (CBS 19579; MycoBank MB864958), and Wickerhamiella solitaria f.a., sp. nov. (CBS 19578; MycoBank MB 864959). Our results suggest that solitary bees could represent a rich source of novel yeast species. In addition, our data do not support the proposed genera Casaregolazyma and Entelexis, and four Candida species are formally reassigned to the genera Starmerella and Zygoascus.

Kluyveromyces lactis is a budding yeast host useful for recombinant protein production; however, its transformation often relies on electroporation due to the perceived low efficiency of chemical methods, thereby limiting throughput. In this study, we developed a robust, small-scale chemical transformation protocol (using 15 μL of competent cells) that achieves high efficiency, particularly with linear DNA. No significant differences in efficiency were observed between lithium chloride and lithium acetate, nor across concentrations ranging from 0.1 to 1.0 M, for making cells competent. The addition of dimethyl sulfoxide (DMSO) during heat shock enhanced colony counts, while ethanol inhibited the process. When PCR fragments containing the optimized pan-genomic autonomous replication sequence (PanARS-OPT) were used for transformation, the transformation efficiency was approximately 7-fold higher than that of circular plasmids, yielding over 10[5] transformants/μg DNA. This high efficiency with linear DNA can be due to a potent non-homologous end-joining (NHEJ) activity in K. lactis. This rapid, "one-tube" method eliminates the need for plasmid construction and specialized equipment, offering a tool for rapid and high-throughput genetic engineering in K. lactis.

Yeasts are model organisms and protein production hosts of choice, in part due to their ease of genetic manipulation. Yeast transformation with DNA on plasmids or integrated into the genome has been developed since the 1970s and is a routine method in many laboratories. However, transformation frequencies are surprisingly low, with common methods yielding around 1% of transformed cells in budding yeast Saccharomyces cerevisiae. In alternative species, there is lower transformation frequency and unreasonably large quantities of input DNA may be required. Surprisingly, the mechanisms by which yeast cells take up DNA are not known. Here we argue that three approaches could deliver a step-change in yeast transformation frequency and efficiency. First, investigating the mechanisms of DNA uptake. The requirement for salts and extraneous polymers-carrier DNA and PEG-in standard protocols suggests that phase separation of DNA may enhance DNA uptake into cells or subsequent nuclear delivery. Second, accounting for the physiological or growth state of the yeast including cell cycle phase and nutrient or stress conditions. Third, systematically determining the factors that affect transformation efficiency using statistical Design of Experiments. These approaches could allow superefficient transformation of S. cerevisiae, and accelerate genetic manipulation of non-model yeasts.

Insects are essential partners for yeasts, playing a key role in their dispersal to new environments. Stingless bees (Apidae: Corbiculata: Meliponini) are social corbiculate bees which lack a functional sting. They are important pollinators in tropical and subtropical regions, foraging for nectar, pollen, and resins, thereby enriching their nests with plant-associated microbes, including yeasts. Here we assessed the yeast diversity associated with stingless bees and their provisions, by thoroughly sampling guts, brood cells, pollen, and honey pots, across seven different Meliponini species: Frieseomelitta varia, Melipona quadrifasciata, Scaptotrigona depilis, Scaptotrigona postica, Tetragona clavipes, Tetragonisca angustula, and Trigona cilipes. Yeast diversity was analyzed for the most extensively sampled bees, S. depilis and T. clavipes. Among the 20 yeast and yeast-like species recovered, we found a core dominant yeast community, primarily composed of Starmerella and Wickerhamiella yeasts, which are notorious to be associated with flowers and floricolous insects. Although the communities are dominated by specific yeast taxa with similar metabolic profiles, it differs among stingless bee species that occur in the same geographic area, as observed for S. depilis and T. clavipes. We suggest that yeast communities associated with stingless bees and their provisions contain overrepresented taxa and are shaped by host foraging choices.

Metschnikowia pulcherrima, an ascomycetous yeast, has been frequently isolated from various substrates associated with agriculture such as nutrient-rich plant materials (fruit, fruit juices and fermenting grape must), soil and with various insects including fruit flies. Due to the growing consumer demand for wines with reduced levels of additives such as sulphites, there has been great interest in this yeast species for its ability to compete with other fungi. Despite having similar phenotypes, many species related to M. pulcherrima have been described in the last 20 years based on the sequences of the LSU D1/D2 domain. These species were grouped together as M. pulcherrima based on primary and secondary barcode sequences, physiological tests and hybridization experiments (Sipiczki 2022a). However, this new classification is supported by limited genetic information. In this project we performed a genomic characterization of 63 strains, including 10 type strains of current synonyms. The combination of different genomic-scale analyses (ANI, k-mer, Busco genes, whole-genome genotyping) conclusively demonstrated the existence of a main cluster of strains representing the M. pulcherrima species and a small sister cluster related to M. chrysoperlae that appeared as potential triploid hybrids. We also observed a high heterozygosity in M. pulcherrima which was significantly higher than S. cerevisiae and the presence of some homozygous strains. Strong linkage disequilibrium decay also suggests active outcrossing leading to recombination in this species. This demonstrates the power of phylogenomic in resolving taxonomic issues and the ability of such approaches to provide information on the life cycle of this species.

Four yeast isolates with an affinity to Hermanozyma ubatubensis and Hermanozyma aechmeae (Ascomycota, Saccharomycotina, and Metschnikowiaceae) were obtained from plant and soil samples collected at different localities in Brazil. Analyses of the D1/D2 domains of the LSU rDNA gene and phylogenomic data indicate that these isolates represent a new species within the Herm. ubatubensis clade. We propose the name Hermanozyma buritii sp. nov., f.a. to accommodate these isolates. The holotype is CBS 19561. The MycoBank number is MB864970. To further characterize this species, genome sequence data were analyzed for genes involved in carbon and nitrogen metabolism and compared with those of Herm. ubatubensis, Herm. aechmeae, and other phylogenetically related yeast species with publicly available genomes from the genera Australozyma, Helenozyma, Metschnikowia, and Tanozyma. Although sporulation and other evidence of sexual reproduction were not observed, genome analyses revealed the presence of the MATα locus in the strain examined. Herm. buritii exhibited the highest diversity of mating pheromone genes among the analyzed species, with five α-pheromone copies (two variants) and seven mfa loci encoding three distinct peptides, suggesting a potentially versatile mating system. Herm. buritii produced a red-maroon pigment when cultivated in the presence of iron, consistent with pulcherrimin formation through the binding of pulcherriminic acid to ferric iron (Fe[3+]). In addition, all four genes required for pulcherriminic acid biosynthesis were identified in its genome. The phenotypic characteristics of the novel species were compared with those of Herm. ubatubensis and Herm. aechmeae.

The future of sustainable industrial biotechnology relies on microbial hosts that can thrive where conventional strains fail. Although Saccharomyces cerevisiae remains the dominant industrial yeast, its metabolic constraints and stress sensitivity highlight the need for alternative microbial chassis. Environmental selection shapes microbial phenotypes, and ecologically diverse isolates represent an underexplored reservoir of industrially relevant traits. Here, we established the Brazilian Yeast Collection (BRYC), comprising 79 isolates spanning 18 genera and 28 named species collected across Brazilian biomes, and systematically characterized their phenotypic diversity under 19 industrially relevant conditions-including carbon sources, biomass-derived inhibitors, elevated temperatures, and high ethanol concentrations-as well as performance on biomass feedstock for industrial bioenergy applications. Across 19 conditions, an industrial S. cerevisiae control ranked first in only one (14% ethanol) despite the panel including strains selected or engineered for low pH tolerance, aldehyde tolerance, xylose utilization, and industrial fermentation performance. 68% of BRYC isolates also exceeded the industrial controls in growth rate robustness. Twenty isolates ranked in the top 10 across three or more conditions, with Wickerhamomyces anomalus (BRYC03 and BRYC30), Pichia kudriavzevii (BRYC98), and Sungouiella flosculorum (BRYC21) emerging as the most versatile performers. Stress-tolerance profiles predicted performance on complex industrial substrates, supporting condition-relevant phenotyping as a framework for rational strain selection. These rankings were, however, substantially format-dependent, with low concordance between liquid and solid cultivation across most conditions (median top-10 overlap = 0.20), underscoring the importance of matching cultivation format to target industrial processes. These findings expand the portfolio of stress-resilient, metabolically versatile yeasts and provide a foundation for their development as next-generation industrial fermenters.

The yeast Spathaspora passalidarum is considered promising for domestication and use in second-generation ethanol production because it ferments xylose and glucose with yields above 70%. However, successful domestication requires not only efficient sugar utilization but also enhanced tolerance to the stresses associated with industrial fermentation, particularly ethanol accumulation, osmotic pressure, and oxidative conditions. To investigate stress responses in Sp. passalidarum, its repertoire of transcription factors and over 300 stress-related proteins were predicted and compared to orthologs in Saccharomyces cerevisiae. While most stress-related proteins were conserved between the two species, more than 70% of Sp. passalidarum transcription factors showed less than 30% sequence identity, lacked recognizable domains, or diverged within functional domains. Gene complementation assays showed that the Sp. passalidarum YAP1 and MSN-like genes showed limited or incomplete complementation of oxidative stress tolerance in S. cerevisiae mutant strains compared with the corresponding native genes. Together, these findings support functional divergence of the analyzed transcription factors in the heterologous S. cerevisiae system and suggest that regulatory divergence may contribute to stress-response differences between Spathaspora passalidarum and Saccharomyces cerevisiae.

The knockout strain collection of Saccharomyces cerevisiae has served as a valuable resource for functional genomics and yeast-based biotechnology studies. A comprehensive single-gene knockout strain collection, covering nearly all non-essential genes, together with complementary mutant collections for essential genes, including temperature-sensitive and transcriptionally regulated strains, has enabled systematic genome-wide analyses of gene function. These resources have facilitated extensive studies of genetic interaction networks, cellular stress responses, metabolic regulation, and adaptive evolution. The yeast knockout strain collection has also been widely utilized in biotechnological research including the identification of genes affecting tolerance to toxic compounds, improvement of metabolite production, and design of synthetic microbial communities, and human disease research such as identification of disease-related genes and treatment targets. This review summarizes the construction and characteristics of the yeast knockout strain collection, key technologies for their application, and recent representative studies in fundamental, biotechnological and human disease research. Furthermore, important considerations for the reliable utilization of the yeast knockout strain collection, including genome instability, neighboring gene effects, and the influence of genetic background, are discussed. Finally, future prospects for applications of the yeast knockout strain collection are outlined.

Over the last three decades, blue native polyacrylamide gel electrophoresis (BN-PAGE), a technique that allows the resolution of large protein complexes in their native conformations, has profoundly impacted the study of mitochondrial biology and our understanding of oxidative phosphorylation (OXPHOS) system's biogenesis and organization. However, while protein samples for BN-PAGE can be prepared from permeabilized mammalian cells, the analysis of yeast OXPHOS complexes requires the prior isolation of mitochondria from whole yeast cells. This requirement limits high-throughput studies and prevents short time-course analyses. We therefore combined BN-PAGE techniques with the cryogenic milling of snap-frozen cells to develop cryoBN-PAGE, which allows for the preparation of BN-PAGE samples from whole-cell yeast lysates and avoids the cost and time associated with mitochondrial isolation. Here, we show the optimization of the method and demonstrate that it can be efficiently paired with a number of downstream applications, such as immunoblots, second-dimension SDS-PAGE, and in gel enzymatic activity assays. Furthermore, by avoiding the time-consuming mitochondrial isolation, cryoBN-PAGE allows for precise time-course assays and the investigation of rapid changes in the properties of the OXPHOS system in response to alterations in environmental conditions.

Yeasts are widespread members of microbial communities across terrestrial, aquatic, and host-associated environments, yet they remain underrepresented in microbiome studies due to low abundance and methodological biases. By combining a literature review with a meta-analysis of ~44,000 fungal metabarcoding samples from the GlobalFungi database, we show that yeasts occur in over 90% of samples, confirming their global ubiquity. Basidiomycetous lineages-especially Agaricomycotina-were most frequently detected, whereas Saccharomycotina showed stronger signals in anthropogenic, aquatic, host-associated, and food-related settings depending on the dataset. Although yeasts typically comprised only ~0.1% of fungal reads, their distributions were structured rather than uniform and reflected distinct habitat associations across environments. In ~3% of samples, yeasts exceeded 25% of reads, with genera such as Aureobasidium, Hanseniaspora, and Saccharomyces episodically dominating nutrient-rich or human-influenced environments. Cosmopolitan genera including Vishniacozyma, Solicoccozyma and Rhodotorula were broadly distributed but remain underreported in microbiome surveys. Shotgun metagenomic data further confirmed yeast presence across diverse microbiomes, with yeast-derived reads being a small fraction of total metagenomic sequences, reflecting the 'curse of low abundance'. Despite their rarity, yeasts are likely to contribute to nutrient cycling, plant growth, and host interactions. We recommend inclusive multi-kingdom approaches-improved primer design, optimised fungal DNA recovery, long-read sequencing, and quantitative tools-to better integrate yeasts into microbiome research.