Metabolomic charactetization of yeast cells after dehydration stress

In this study, we analyzed the metabolite features of the yeasts Saccharomyces cerevisiae, Naumovia castellii, and Saccharomyces mikatae. The three species are closely related genetically but differ in their tolerance of desiccation stress. Specifi cally, we determined whether certain metabolites correlated with cell viability after stress imposition. The metabolomic profi les of these strains were compared before cell desiccation and after cell rehydration. In S. mikatae, the presence of lysine or glutamine during rehydration led to a 20% increase in survival whereas during dehydration the levels of both amino acids in this yeast were drastically reduced. [Int Microbiol 2014; 17(3):131-139]  Keywords: Saccaromyces mikatae · Saccharomyces cerevisiae · Naumovia castellii · viability · dehydration stress · metabolite extraction · wild yeas

Isolation, selection, and characterization of highly ethanol-tolerant strains of Oenococcus oeni from south Catalonia

Twenty-one strains of Oenococcus oeni were isolated during the malolactic fermentation of wines from south Catalonia. Due to their high ethanol tolerance (14 %, or more), these strains may serve as promising starters. The strains were screened by assays in a wine-like medium and by their co-inoculation in wine, resulting in the selection of well-performing strains, subsequently shown not to produce the main biogenic amines and lacking the genes involved in their synthesis. The genetic diversity of the isolates was studied by multilocus sequence typing (MLST), in which seven housekeeping genes were sequenced. Although the concatenated allelic profi le of some strains was the same, the profi les obtained by random amplifi cation of polymorphic DNA together with the variable number of tandem repeats at several loci showed that none of the strains were identical. A phylogenetic tree was constructed based on MLST with the seven genes and clearly showed two phylogroups, in accordance with previous studies. The best-performing strains occurred in members of both subgroups, suggesting that the grouping of housekeeping genes is not directly related to adaptation and ethanol tolerance. [Int Microbiol 2013; 16(2):113-123]Keywords: Oenococcus oeni; malolactic fermentation; wine production; multilocus sequence typing (MLST);strain selectio

New Insights about the Influence of Yeasts Autolysis on Sparkling Wines Composition and Quality

Sparkling wines elaborated using the traditional method undergo a second fermentation in the bottle. This process involves an aging time in contact with the lees, which enriches the wine in various substances, especially proteins, mannoproteins and polysaccharides, thanks to the autolysis of the yeasts. As a result of this yeast autolysis, sparkling wines benefit from better integration of carbon dioxide and a clear sensory improvement, especially in the case of long aging. This chapter synthetizes the main results that our research group has obtained about the influence of yeasts autolysis on sparkling wines composition and quality during last years, making special emphasis on the capacity of the lees to release proteins and polysaccharides as well as on their capacity to consume oxygen and thus protect the sparkling wines from oxidation

Différenciation des principales espèces de levures de vin par l'analyse des acides gras libres totaux par chromatographie en phase gazeuse

La différenciation des levures de fermentation des levures de contamination du vin par l'analyse de leurs profils en acides gras libres totaux a été évaluée. L'étude porte sur 39 souches de levures représentant 24 espèces. Les cultures se déroulent à la température de 28°C, en aérobiose et en milieu liquide. Par cette méthode, il est possible de différencier S. cerevisioe des autres genres de levures, mais il semble toutefois difficile de déterminer de façon exacte la souche responsable de la contamination. Enfin, ces résultats montrent qu'il est important d'étudier le métabolisme des acides gras, molécules indispensables à la survie des cellules afin de comprendre certaines réponses physiologiques des différentes espèces de levures

Data supporting the results published in the paper entitled "Sterol composition modulates the response of Saccharomyces cerevisiae to iron deficiency"

The dataset is made available under the Open Database License. Any rights in individual contents of the database are licensed under the Database Contents License. Please, read the full ODbL 1.0 license text for the exact terms that apply. Users of the dataset are free to: Share: copy, distribute and use the database, either commercially or non-commercially. Create: produce derivative works from the database. Adapt: modify, transform and build upon the database. Under the following conditions: Attribution: You must attribute any public use of the database, or works produced from the database. For any use or redistribution of the database, or works produced from it, you must make clear to others the license of the original database. Share-Alike: If you publicly use any adapted version of this database, or works produced from an adapted database, you must also offer that adapted database under the ODbLPeer reviewe

Sterol Composition Modulates the Response of Saccharomyces cerevisiae to Iron Deficiency

Iron is a vital micronutrient that functions as an essential cofactor in multiple biological processes, including oxygen transport, cellular respiration, and metabolic pathways, such as sterol biosynthesis. However, its low bioavailability at physiological pH frequently leads to nutritional iron deficiency. The yeast Saccharomyces cerevisiae is extensively used to study iron and lipid metabolisms, as well as in multiple biotechnological applications. Despite iron being indispensable for yeast ergosterol biosynthesis and growth, little is known about their interconnections. Here, we used lipid composition analyses to determine that changes in the pattern of sterols impair the response to iron deprivation of yeast cells. Yeast mutants defective in ergosterol biosynthesis display defects in the transcriptional activation of the iron-acquisition machinery and growth defects in iron-depleted conditions. The transcriptional activation function of the iron-sensing Aft1 factor is interrupted due to its mislocalization to the vacuole. These data uncover novel links between iron and sterol metabolisms that need to be considered when producing yeast-derived foods or when treating fungal infections with drugs that target the ergosterol biosynthesis pathway.</jats:p