Biology subjects

Yurimoto, H.

Publications and source records attributed to Yurimoto, H..

5 recordsLinked to original sources

bioRxiv2026

High extracellular osmolarity promotes yeast thermotolerance through osmotic modulation and glycerol-dependent adaptation.

High-temperature stress is a major constraint on yeast growth and fermentation, and has traditionally been interpreted primarily in terms of intracellular molecular damage such as protein denaturation and aggregation. Despite this extensive focus on intracellular mechanisms, how physical factors within the extracellular environment influence yeast thermotolerance remains poorly understood. Here we demonstrate that increases in extracellular osmolarity markedly attenuate growth inhibition under high-temperature conditions in yeast. This protective effect was consistently observed in multiple laboratory and industrial strains of Saccharomyces cerevisiae, as well as in ascomycetous and basidiomycetous yeasts, indicating that osmotic pressure-dependent thermotolerance is a broadly conserved phenomenon. We also found that extracellular osmolarity dynamically increases during growth and then decreases in a diauxic shift-like pattern after growth arrest. At high temperature, the secretion of glucose-derived metabolites decreased, but that of other solutes increased, suggesting that heat stress alters the composition of extracellular solutes contributing to osmolarity. In addition, intracellular glycerol levels increased at high temperature, and this increase was further enhanced under high-osmolarity conditions. Notably, expression of a constitutively active Hog1 mutant exhibited raised intracellular glycerol levels, enhanced nuclear localization of Hog1, and improved growth under high-temperature conditions. Collectively, these findings support a model in which extracellular osmolarity is modulated to avoid excessive intracellular osmolarity under high-temperature conditions, while the intracellular accumulation of glycerol contributes to yeast adaptation at high-temperature. Our results highlight extracellular-intracellular osmotic coordination as an additional physiological layer of high-temperature stress adaptation in yeast.

microbiology↗

bioRxiv2026

Phenotypic diversity of yeasts curated in the 5th edition of The Yeasts: A data-driven visualization approach

Yeasts have long served as key experimental systems in genetics, cell biology, and fermentation research; however, these studies have largely focused on a limited number of model species. In contrast, yeasts are a fungal group with remarkable physiological and ecological diversity. To provide a global overview of yeast diversity, we compiled and visualized phenotypic information for approximately 1,300 yeast species documented in The Yeasts (5th edition), including carbon utilization profiles, fermentation capacity, growth temperature ranges, and reported isolation sources. Taxonomic reconciliation revealed extensive reannotation, with approximately 44% of the species undergoing name changes and recognized genera increasing from 143 to 233. Integrative analyses revealed pronounced phylogenetic structuring of metabolic breadth. Many basidiomycetous yeasts, particularly Agaricomycotina, exhibited broader, generalist-like carbon utilization, whereas ascomycetous yeasts, especially Saccharomycotina, more frequently displayed sugar-centered, specialist-like narrower profiles; model yeasts such as Saccharomyces cerevisiae and Schizosaccharomyces pombe fell at the narrow end of this spectrum. Fewer than half of all species fermented glucose, a trait largely confined to Saccharomycotina. In addition, nearly one-fifth of species failed to grow at 30 {degrees}C, the standard laboratory temperature. By reconstructing and visualizing decades of dispersed taxonomic knowledge accumulated in The Yeasts, this study reframes yeasts not merely as laboratory model organisms but as metabolically diverse fungi whose phenotypic diversity reflects diverse ecological contexts. The analytical framework presented here provides a foundation for integrating standardized quantitative phenotypes and newly described species and offers a starting point for exploring the latent ecological and metabolic potential of yeast diversity.

microbiology↗

bioRxiv2025

P-body formation is required for yeast proliferation in the phyllosphere

Processing bodies (P-bodies) are major cytosolic ribonucleoprotein granules involved in post-transcriptional regulation. Yeast has been an invaluable model for elucidating the functions of P-bodies under laboratory conditions. However, the physiological significance of P-bodies in natural environments remains unclear. Here, we demonstrate that P-body formation is required for yeast proliferation in the phyllosphere, the aerial parts of plants. Deletion of EDC3, a gene critical for P-body formation, impaired proliferation of the methanol-utilizing yeast Candida boidinii on Arabidopsis thaliana leaves where the yeast assimilates methanol as the carbon source while adapting to changes in environmental conditions. In vitro experiments showed that P-bodies contribute to the spatiotemporal regulation of methanol-induced mRNAs (mimRNAs). These mimRNAs form cytosolic dot structures (termed mimRNA granules) that harbor multiple kinds of mimRNAs. In the edc3{Delta} strain, the formation of mimRNA granules was reduced along with a decrease in mimRNA abundance. Under oxidative stress, colocalization of P-bodies with mimRNA granules markedly increased and growth of the edc3{Delta} strain on methanol was suppressed, suggesting active sequestration of mimRNAs within P-bodies as a stress tolerance response. Time-lapse microscopy revealed dynamic interactions between P-bodies and mimRNAs granules with transient colocalization. Together, our findings indicate that P-bodies function as temporal storage sites where mimRNAs are protected from degradation in the phyllosphere. Impact statementP-bodies support yeast survival on plant leaves by sequestering and protecting methanol-induced mRNAs from degradation

microbiology↗

bioRxiv2025

Methylotrophic yeast Candida boidinii enhances the colonization of plant growth-promoting yeast Papiliotrema laurentii in the phyllosphere

Methanol-utilizing microbes are ubiquitous in the phyllosphere, where they assimilate methanol released from pectin, the major component of the plant cell wall. While methylotrophic bacteria Methylobacterium spp. are well studied for their symbiotic relationships with the host plants, the ecology and functional roles of methylotrophic yeasts on plants remain poorly understood. In the effort to isolate yeasts from 26 phyllosphere samples, we identified Candida boidinii as the only methylotrophic yeast, while the remaining isolates, categorized into 17 species in 12 genera, lacked this metabolic trait. To obtain insight into the role of methylotrophic yeasts in the phyllosphere, we investigated the interaction of C. boidinii with a plant growth-promoting yeast (PGPY), Papiliotrema laurentii, one of the identified yeast species during isolation. We found that the colonization of P. laurentii was enhanced by the presence of C. boidinii on Arabidopsis thaliana leaves. Co-cultivation assays revealed that the cell yield of P. laurentii was enhanced by C. boidinii during cultivation on pectin and that the methanol-utilizing ability and pectin methylesterase (PME) activity of C. boidinii contributed to this enhancement. Stable carbon isotope labeling of pectin methylester groups unambiguously confirmed their assimilation by C. boidinii, but not by P. laurentii. These findings suggest that C. boidinii not only survives in the phyllosphere by utilizing pectin-derived methanol but also contributes to the fitness of other yeast species through metabolic cooperation. This study provides new insights into the niche construction and survival strategies of phyllosphere methylotrophic yeasts, highlighting their potential role in shaping microbial community dynamics and promoting beneficial plant-microbe interactions.

microbiology↗

bioRxiv2024

Methanol chemoreceptor MtpA- and flagellin protein FliC-dependent methylotaxis determines the spaciotemporal colonization of PPFM in the phyllosphere

Pink-pigmented facultative methylotrophs (PPFMs) capable of growth on methanol are dominant and versatile phyllosphere bacteria that provide positive effects on plant growth through symbiosis. However, the spatiotemporal behavior of PPFMs on plant surfaces and its molecular basis are unknown. Here we show that Methylobacterium sp. strain OR01 inoculated onto red perilla seeds colonized across the entire plant surface in the phyllosphere concomitant with the plant growth. FliC flagellin proteins required for motility were necessary for distributed colonization on plant leaves, but not for colonization at the leaf periphery. Methanol-sensing chemoreceptor MtpA-dependent chemotaxis (methylotaxis; chemotaxis toward methanol) facilitated the bacterial movement from the peripheral to the inner part of leaves and further entry into the stomatal cavity, indicating that methanol functions as a volatile messenger attracting PPFMs to particular leaf locations possibly to support with photosynthesis and to afford protection from pathogenic invasion.

microbiology↗