FEMS yeast research最新文献

Data makes the world go round-and high quality data is a prerequisite for precise models, especially for whole-cell models (WCM). Data for WCM must be reusable, contain information about the exact experimental background, and should-in its entirety-cover all relevant processes in the cell. Here, we review basic requirements to data for WCM and strategies how to combine them. As a species-specific resource, we introduce the Yeast Cell Model Data Base (YCMDB) to illustrate requirements and solutions. We discuss recent standards for data as well as for computational models including the modeling process as data to be reported. We outline strategies for constructions of WCM despite their inherent complexity.

Plastics have become an indispensable material in many fields of human activities, with production increasing every year; however, most of the plastic waste is still incinerated or landfilled, and only 10% of the new plastic is recycled even once. Among all plastics, polyethylene terephthalate (PET) is the most produced polyester worldwide; ethylene glycol (EG) is one of the two monomers released by the biorecycling of PET. While most research focuses on bacterial EG metabolism, this work reports the ability of Saccharomyces cerevisiae and nine other common laboratory yeast species not only to consume EG, but also to produce glycolic acid (GA) as the main by-product. A two-step bioconversion of EG to GA by S. cerevisiae was optimized by a design of experiment approach, obtaining 4.51 ± 0.12 g l-1 of GA with a conversion of 94.25 ± 1.74% from 6.21 ± 0.04 g l-1 EG. To improve the titer, screening of yeast biodiversity identified Scheffersomyces stipitis as the best GA producer, obtaining 23.79 ± 1.19 g l-1 of GA (yield 76.68%) in bioreactor fermentation, with a single-step bioprocess. Our findings contribute in laying the ground for EG upcycling strategies with yeasts.

Climate change and consumer preferences are driving innovation in winemaking, with a growing interest in non-Saccharomyces species. Among these, Torulaspora delbrueckii (Td) has gained recognition for its ability to reduce volatile acidity and enhance aromatic complexity in wine. However, knowledge regarding its phenotypic and genomic diversity impacting alcoholic fermentation remains limited. Aiming to elucidate the metabolic differences between Td and Saccharomyces cerevisiae (Sc) and the Td intraspecies diversity, we conducted a comprehensive metabolic characterization of 15 Td strains. This analysis delved beyond standard fermentation parameters (kinetics and major metabolites production) to explore non-conventional aromas and establish genotype-phenotype links. Our findings confirmed that most Td strains produce less acetic acid and more succinate and glycerol than Sc. The overall aromatic profiles of Td strains differed from Sc, exhibiting higher levels of monoterpenes and higher alcohols, while producing less acetate esters, fatty acids, their corresponding ethyl esters, and lactones. Moreover, we identified the absence of genes responsible for specific aroma profiles, such as decreased ethyl esters production, as well as the absence of cell wall genes, which might negatively affect Td performance when compared to Sc. This work highlights the significant diversity within Td and underscores potential links between its genotype and phenotype.

Emergomyces africanus is a thermally dimorphic pathogen causing severe morbidity and mortality in immunocompromized patients. Its transition to a pathogenic yeast-like phase in the human host is a notable virulence mechanism. Recent studies suggest polyamines as key players in dimorphic switching, yet their precise functions remain enigmatic. This work aimed to explore polyamine metabolism of two clinical strains of E. africanus (CBS 136260 and CBS 140360) in mycelial and yeast-like phases. In this first report of the polyamine profile of E. africanus, we reveal, using mass spectrometry, spermidine, and spermine as the major polyamines in both phases. The secretion of these amines was significantly higher in the pathogenic yeast-like phase than in the mycelial phase, warranting further investigation into the implications thereof on virulence. Additionally, we detected the activity of several polyamine biosynthesis enzymes, including arginine decarboxylase, agmatinase, arginase, and ornithine decarboxylase, with significant differences in enzyme expression between morphological phases and strains. Finally, we provide initial evidence for the requirement for spermine, spermidine, and putrescine during the thermally induced dimorphic switch of E. africanus, with strain-specific differences in the production of these amines. Overall, our study presents novel insight into polyamine metabolism and its role in dimorphism of E. africanus.

In this study, we explored the sphingolipid (SL) landscape in Candida auris, which plays pivotal roles in fungal biology and drug susceptibility. The composition of SLs exhibited substantial variations at both the SL class and molecular species levels among clade isolates. Utilizing principal component analysis, we successfully differentiated the five clades based on their SL class composition. While phytoceramide (PCer) was uniformly the most abundant SL class in all the isolates, other classes showed significant variations. These variations were not limited to SL class level only as the proportion of different molecular species containing variable number of carbons in fatty acid chains also differed between the isolates. Also a comparative analysis revealed abundance of ceramides and glucosylceramides in fluconazole susceptible isolates. Furthermore, by comparing drug-resistant and susceptible isolates within clade IV, we uncovered significant intraclade differences in key SL classes such as high PCer and low long chain base (LCB) content in resistant strains, underscoring the impact of SL heterogeneity on drug resistance development in C. auris. These findings shed light on the multifaceted interplay between genomic diversity, SLs, and drug resistance in this emerging fungal pathogen.

Morphological phenotyping of the budding yeast Saccharomyces cerevisiae has helped to greatly clarify the functions of genes and increase our understanding of cellular functional networks. It is necessary to understand cell morphology and perform quantitative morphological analysis (QMA) but assigning precise values to morphological phenotypes has been challenging. We recently developed the Unimodal Morphological Data image analysis pipeline for this purpose. All true values can be estimated theoretically by applying an appropriate probability distribution if the distribution of experimental values follows a unimodal pattern. This reliable pipeline allows several downstream analyses, including detection of subtle morphological differences, selection of mutant strains with similar morphology, clustering based on morphology, and study of morphological diversity. In addition to basic research, morphological analyses of yeast cells can also be used in applied research to monitor breeding and fermentation processes and control the fermentation activity of yeast cells.

Advances in yeast biotechnology rely on the application of knowledge gained using modern biotechnological tools to harness the metabolic repertoire of various yeast genera that have been studied in detail. In my work, I have attempted to combine knowledge gained from academic research with industrial knowhow in practical cost-effective ways to scale up commercial yeast fermentations from one hundred thousand to greater than one million liters. Among the processes I scaled up and/or optimized to production scale include biofuels, chemicals, food and feed additives. During a long industrial career that spanned over three decades, I leveraged what was often very challenging work with many academic, government, and industrial scientists engaging them in collaborative research to ensure a successful outcome. Many of these collaborators responded in kind and are part of this narrative. In many ways, my journey was also theirs. However, I acquired the scientific foundation or starting point much earlier during my undergraduate studies learning from great professors that helped me understand the complexity of science while convincing me of the value of pursuing research as a career.