Search results for " wine."
showing 10 items of 331 documents
The Use of Mixed Populations of Saccharomyces cerevisiae and S. kudriavzevii to Reduce Ethanol Content in Wine: Limited Aeration, Inoculum Proportion…
2017
Saccharomyces cerevisiae is the most widespread microorganism responsible for wine alcoholic fermentation. Nevertheless, the wine industry is currently facing new challenges, some of them associate with climate change, which have a negative effect on ethanol content and wine quality. Numerous and varied strategies have been carried out to overcome these concerns. From a biotechnological point of view, the use of alternative non-Saccharomyces yeasts, yielding lower ethanol concentrations and sometimes giving rise to new and interesting aroma, is one of the trendiest approaches. However, S. cerevisiae usually outcompetes other Saccharomyces species due to its better adaptation to the fermenta…
Genetic Polymorphism in Wine Yeasts: Mechanisms and Methods for Its Detection
2017
The processes of yeast selection for using as wine fermentation starters have revealed a great phenotypic diversity both at interspecific and intraspecific level, which is explained by a corresponding genetic variation among different yeast isolates. Thus, the mechanisms involved in promoting these genetic changes are the main engine generating yeast biodiversity. Currently, an important task to understand biodiversity, population structure and evolutionary history of wine yeasts is the study of the molecular mechanisms involved in yeast adaptation to wine fermentation, and on remodeling the genomic features of wine yeast, unconsciously selected since the advent of winemaking. Moreover, the…
Flor Yeast Diversity and Dynamics in Biologically Aged Wines
2018
International audience; Wine biological aging is characterized by the development of yeast strains that form a biofilm on the wine surface after alcoholic fermentation. These yeasts, known as flor yeasts, form a velum that protects the wine from oxidation during aging. Thirty-nine velums aged from 1 to 6 years were sampled from "Vin jaune" from two different cellars. We show for the first time that these velums possess various aspects in term of color and surface aspects. Surprisingly, the heterogeneous velums are mostly composed of one species, S. cerevisiae. Scanning electron microscope observations of these velums revealed unprecedented biofilm structures and various yeast morphologies f…
Use of autochthonous yeasts and bacteria in order to control Brettanomyces bruxellensis in wine
2017
Biocontrol strategies for the limitation of undesired microbial developments in foods and beverages represent a keystone toward the goal of more sustainable food systems. Brettanomyces bruxellensis is a wine spoilage microorganism that produces several compounds that are detrimental for the organoleptic quality of the wine, including some classes of volatile phenols. To control the proliferation of this yeast, sulfur dioxide is commonly employed, but the efficiency of this compound depends on the B. bruxellensis strain; and it is subject to wine composition and may induce the entrance in a viable, but nonculturable state of yeasts. Moreover, it can also elicit allergic reactions in humans. …
The genetic architecture of low-temperature adaptation in the wine yeast Saccharomyces cerevisiae
2017
[Background] Low-temperature growth and fermentation of wine yeast can enhance wine aroma and make them highly desirable traits for the industry. Elucidating response to cold in Saccharomyces cerevisiae is, therefore, of paramount importance to select or genetically improve new wine strains. As most enological traits of industrial importance in yeasts, adaptation to low temperature is a polygenic trait regulated by many interacting loci.
Biotechnological impact of stress response on wine yeast.
2016
Wine yeast deals with many stress conditions during its biotechnological use. Biomass production and its dehydration produce major oxidative stress, while hyperosmotic shock, ethanol toxicity and starvation are relevant during grape juice fermentation. Most stress response mechanisms described in laboratory strains of Saccharomyces cerevisiae are useful for understanding the molecular machinery devoted to deal with harsh conditions during industrial wine yeast uses. However, the particularities of these strains themselves, and the media and conditions employed, need to be specifically looked at when studying protection mechanisms.
Herbicide glufosinate inhibits yeast growth and extends longevity during wine fermentation.
2017
Glufosinate ammonium (GA) is a widely used herbicide that inhibits glutamine synthetase. This inhibition leads to internal amino acid starvation which, in turn, causes the activation of different nutrient sensing pathways. GA also inhibits the enzyme of the yeast Saccharomyces cerevisiae in such a way that, although it is not used as a fungicide, it may alter yeast performance in industrial processes like winemaking. We describe herein how GA indeed inhibits the yeast growth of a wine strain during the fermentation of grape juice. In turn, GA extends longevity in a variety of growth media. The biochemical analysis indicates that GA partially inhibits the nutrient sensing TORC1 pathway, whic…
Improved detection and enumeration of yeasts in wine by Cells-qPCR
2018
Abstract Quantitative PCR by directly sampling (Cells-qPCR) has been adapted to detect and quantify total yeasts, and B. bruxellensis, S. cerevisiae and Z. bailii species, in grape musts and wines. To increase assay sensitivity, the effects of a previous cell wall lysis, by both enzymatic and mechanical methods, were evaluated. Cell wall disruption by mechanical methods showed the best results to enhance assay sensitivity. Numerous standard curves were constructed by mechanically lysed cells in culture medium, and in white and red grape musts and wines. Good regression values (>0.99) and efficiencies (>0.99) were obtained, and it was possible to detect one single cell per reaction in all th…
Functional Genomics in Wine Yeast: DNA Arrays and Next Generation Sequencing
2017
Since their very beginning, DNA array and next-generation sequencing technologies have been used with Saccharomyces cerevisiae cells. In the last 7 years, an increasing number of studies have focused on the study of wine strains and winemaking. The uncovering of the genomic features of these strains and expression profiles under the different stressful conditions that they have to deal with have contributed significantly to the knowledge of how this amazing microorganism can convert grape must into a drink that has enormously influenced mankind for 7000 years.This review presents a synopsis of DNA array and next-generation sequencing (NGS) technologies and focus mainly in their use in study…
Evolution of yeast populations during different biodynamic winemaking processes
2016
This work was performed to evaluate the evolution of indigenous yeasts during wine productions carried out following the principles of biodynamic agriculture. Five trials were designed with different technological interventions consisting of the addition of nitrogen (in the form of ammonium salt), thiamine salt, oxygen, and pied de cuvee at varying concentrations. Yeasts were estimated by haemocytometer chamber and plate counts and identified by sequencing of the D1/D2 domain of the 26S rRNA gene. The isolates identified as Saccharomyces cerevisiae were found to dominate must fermentations and were genetically differentiated by interdelta sequence analysis (ISA). Several non-Saccharomyces s…