FEMS yeast research最新文献

The Starmerella clade is known for displaying osmotolerant and acidophilic traits from their association with bees. Several species in this genus can produce sophorolipids, which are commercially produced as biosurfactants. Here, we isolated a yeast contaminant from the laboratory environment, identified as Starmerella batistae, able to thrive at low pH and relative high temperatures. We sequenced and conducted a de novo genome assembly in three chromosomes and a mitochondrial genome for S. batistae (ca. 9.3 Mb). Based on this reference genome we functionally annotated 29 Starmerella species, using the publicly available sequences. Phylogenetic analysis across different yeast clades revealed a close relationship between Starmerella and Schizosaccharomyces yeasts. Fifteen genes were uniquely shared between Sz. pombe and S. batistae, of which twelve were involved in cell morphology, reflecting the fact that S. batistae cells are elongated rather than round. We found that all the Starmerella sophorolipid-producing strains shared a close common ancestor. One-to-one orthologs of S. bombicola sophorolipid pathway were only found in S. kuoi (full pathway, but inverted), and in S. powellii and S. floricola (partial pathway). These findings support the notion that alternative pathways for the production of sophorolipids have evolved in different Starmerella lineages.

Whisky is an alcoholic beverage derived from fermented grain mash that is distilled into "new make spirit" before maturing in barrels. While most research on whisky innovation has focused on raw materials or maturation, yeast strain selection remains a relatively underexplored avenue for product diversification. Here, we evaluated yeast diversity for whisky production by screening 110 strains sourced from Canadian vineyards for maltose utilization followed by assessing 29 candidate strains in malt extract fermentations. Seven strains representing distinct genetic backgrounds were advanced to pilot-scale fermentations, including a commercial whisky control strain of Saccharomyces cerevisiae, four other S. cerevisiae strains, one Torulaspora delbrueckii strain, and one Saccharomyces uvarum strain isolated from British Columbia wine fermentations. Fermentation performance was assessed via high performance liquid chromatography, and volatile organic compounds in new make spirits were profiled using headspace solid-phase microextraction-gas chromatography-mass spectrometry. All strains completed fermentation except Torulaspora delbrueckii, despite undergoing sequential inoculation with a commercial whisky strain. Fermentations with non-S. cerevisiae yeast strains contained elevated levels of glycerol and organic acids. Volatile organic compounds analysis identified 43 compounds, revealing strain-dependent aroma diversity. Notably, S. uvarum P01E08 was enriched in 2-phenylethyl octanoate, phenylethyl alcohol, and phenylethyl acetate. These findings highlight diverse regional yeast selection as a viable strategy to expand whisky sensory diversity.

Acetic acid (AA), a natural by-product of ethanol fermentation in yeast cells, is widely present in lignocellulosic hydrolysate as a fermentation inhibitor. Thus, gaining insight into the molecular mechanisms of AA tolerance in yeast is particularly relevant for industrial applications. This study investigates the response to AA stress in two Saccharomyces cerevisiae strains (ATCC 9804 and ATCC 13007) during different metabolic states (fermentation, respiro-fermentation, and respiration) and external pH levels (3․0 and 4.5). The results show that AA reduces the viability of both strains in a dosage-dependent manner. Moreover, ATCC 13007 is more sensitive to AA stress compared to ATCC 9804. Respiratory metabolism and higher pH correlate with better resistance to AA stress. Catalase activity was observed to increase by 1.5-6-fold under AA stress conditions, in accordance with changes in yeast thiol group content and growth. The influence of AA stress is reactive oxygen species-dependent, and redox balance regulation was found to increase the robustness of S. cerevisiae ATCC 13007 to AA by 2-fold. The study reveals valuable insights into yeast adaptation to stress conditions, contributing to the development of robust yeast strain construction for high-yield biomass and chemicals production.

High-throughput yeast engineering is being transformed by biofoundries that integrate automation, artificial intelligence (AI), and standardised workflows. This review examines how these facilities accelerate strain development through the Design-Build-Test-Learn (DBTL) cycle, with advances in genome editing, phenotypic screening, and predictive modelling. It highlights Australia's involvement through the Australian Genome Foundry, Idea-BIO and the CSIRO Biofoundiry and explores global efforts to overcome reproducibility and standardisation challenges. Despite progress, key barriers remain, including protocol variability and integration of AI tools. We also highlight the opportunity for a shift toward autonomous, self-optimising "self-driving labs" that transition from DBTL to Design-Build-Deploy cycles. The future of yeast engineering depends not only on technological innovation, but also on the harmonisation of international standards, data governance, and ethical safeguards. If fully realised, the convergence of robotics, AI, and synthetic biology will redefine yeast engineering, leading to step changes in strain performance for a variety of important products, thus enabling economic and sustainable biomanufacturing at scale.

The large-scale cultivation of microalgae for aquaculture feed, biofuels, and high value bioproducts is often limited by microbial contamination. While bacteria have long been recognized as major algal symbionts, yeasts, though typically less abundant, are emerging as functionally significant members of the phycosphere. Yeast physiological versatility, stress tolerance, and production of bioactive metabolites enable them to exert disproportionate ecological and biotechnological influence relative to their abundance. Yeasts contribute to algal systems through metabolic complementarity, enhancing nutrient cycling, stress resilience, and culture stability. Several yeast species secrete auxins such as indole-3-acetic acid (IAA), stimulating algal cell division and photosynthetic efficiency. Biosurfactants that suppress microbial contaminants, prevent biofilm formation, and stabilize algal cultures are also produced by several yeast species. In co-cultivation systems, yeast-microalgae interactions enhance biomass, lipids, and pigment yields whilst enabling efficient use of waste substrates. Moreover, yeasts associated with microalgae are valuable producers of compounds of biotechnological relevance such as lipids, biosurfactants, pigments, enzymes and other proteins. This review synthesizes current knowledge on yeast-microalgae associations, emphasizing their ecological relevance, functional versatility, and underexplored potential in sustainable bioprocesses and circular bioeconomy. Highlighting yeasts within algal microbiomes provides new insight into cross-kingdom cooperation and tools for developing resilient, high-performance cultivation systems.

Saccharomycotina are a subphylum of ascomycete fungi with diverse asexual growth morphologies. Filamentous growth can comprise linear and branched budding cells that do not undergo cell separation, termed pseudohyphae, or tubular filaments with septa that perforate allowing movement of organelles, termed true hyphae. We integrated phenotypic, genomic, metabolic, and environmental data on isolation sources from 1 051 species to examine the variation and evolutionary history of filamentation across Saccharomycotina and determine whether these data could predict filamentation types. We found that 63.37% of strains can form filaments; 6.56% true hyphae, 42.40% pseudohyphae, and 14.39% both true hyphae and pseudohyphae. The distributions of species that can produce true hyphae or filament were more strongly correlated with the yeast phylogeny than the distribution of species with pseudohyphae. Ancestral state reconstruction suggested that true hyphal and pseudohyphal morphologies evolved several times, that most yeast ancestors likely produced pseudohyphae or lacked filaments, and that the Saccharomycotina last common ancestor likely produced pseudohyphae but not true hyphae. Machine learning models trained on genomic and metabolic features predicted filament morphologies with ∼70% accuracy. Connecting the evolution of morphologies to their genomic, physiological, and ecological characteristics will enrich our understanding of how the diversity of lifestyles evolved in Saccharomycotina.

This article explains the biochemical basis of the synergistic effect of oxythiamine (OT) and ketoconazole (KTC) against Malassezia pachydermatis yeast, which was isolated from dogs exhibiting clinical signs of otitis externa. All strains were incubated on MLNA medium supplemented with OT, KTC, or a mixture of both compounds. We found that the ergosterol content was reduced by the compounds tested, both separately (20%-50%) and in combination (80%). OT alone and in combination with KTC reduced NADPH levels. However, we found no differences in acetyl-CoA levels under the influence of the compounds tested. We suggest that the synergism of OT and KTC is due to a reduction in the rate of the mevalonate pathway by inhibition of NADPH influx from the pentose phosphate pathway (transketolase inhibition by OT) and inhibition of C14-α-lanosterol demethylase by KTC. The proposed mechanism may be versatile for other yeast-like species, making the combination of OT and KTC a promising treatment option for superficial, opportunistic yeast-like infections.

Microbial antagonism, including predation and competition, shapes microbial community diversity and dynamics. Saccharomycopsis schoenii, a unicellular predatory yeast, serves as a distinct model for bona fide fungal predation, characterized by penetration pegs that enable predation. This study examined prey preferences of S. schoenii within wine-associated yeast consortia and assessed the role of prey adhesion and cell wall features in modulating predation efficiency. Predation assays revealed species-specific dynamics, with Saccharomyces cerevisiae showing pronounced susceptibility and Torulaspora delbrueckii displaying resistance indicative of density-dependent prey switching. Expression of prey Flo-adhesins in S. cerevisiae did not affect predation outcomes, highlighting that prey adhesion phenotypes are not primary determinants of susceptibility. In contrast, S. cerevisiae VIN13-related mutant strains with increased cell wall chitin showed variable resistance phenotypes, suggesting that chitin contributes to resistance, but that broader cell wall remodelling and structural features are relevant factors independent of chitin levels. While these findings provide a mechanistic framework for understanding predator-prey interactions and prey resistance, the ecological and evolutionary significance of these interactions remains uncertain due to the rarity of Saccharomycopsis species in natural communities. Ultimately, these results emphasize the importance of integrating laboratory and ecological perspectives to fully comprehend the evolutionary implications of fungal predatory behaviour.

Humans have generated ecological and environmental disturbances, such as vineyards, across the globe. Disturbed environments create widespread and repeated selective pressures that can drive colonization and local adaptation in microbial species. We investigated the distribution of fermentative yeast species in vineyards compared to nearby arboreal habitats and measured their resistance to two commonly used vineyard antimicrobials, copper and sulfite. We analyzed 4 101 strains, representing 70 species, collected from grapevine- and oak-associated substrates at 17 vineyard and 20 non-vineyard sites in the USA and Slovenia. Species frequency varied with geography and substrate, but the majority of species commonly present in vineyards were also found in non-vineyard arboreal environments, representing a potential source for vineyard colonization and exploitation of sugar from grapes. Species varied in both copper and sulfite resistance, but only Saccharomyces cerevisiae showed elevated resistance in vineyard compared to non-vineyard samples. Our results indicate that S. cerevisiae has uniquely taken advantage of vineyard environments through adaptations that appear either unnecessary or inaccessible to other yeast species present in vineyards.

Fission yeast is the ideal model organism for studying telomere maintenance in higher eukaryotes. Telomere length has been directly correlated with life expectancy and the onset of aging-related diseases in mammals. In this study, we developed a novel simple, and reproducible method to measure the telomere length, by investigating the effect of caffeine and cisplatin on the telomere length in fission yeast. Hydroxyurea-synchronized fission yeast cells were exposed to 62 µM cisplatin and 8.67 mM caffeine treatments for 2 h, then their telomere lengths were evaluated with two different methods. First, the quantitative polymerase chain reaction (qPCR) assay was used as a confirmative method, where telomere length was determined relative to a single-copy gene in the genome. Second, the newly developed method standard polymerase chain reaction (PCR)/ImageJ assay assessed the telomere length based on the amplified PCR band intensity using a set of telomere primers, reflecting telomeric sequence availability in the genome. Both methods show a significant decrease and a notable telomere lengthening in response to cisplatin and caffeine treatments, respectively. The finding supports the accuracy and productivity of the standard PCR/ImageJ assay as it can serve as a quick screening tool to study the effect of suspected chemotherapeutic and antiaging drugs on telomere length in fission yeast.