Search results for "yeast"
showing 10 items of 792 documents
Analysis of non-Saccharomyces yeast populations isolated from grape musts from Sicily (Italy).
2008
Aims The aim of this study was to identify the non-Saccharomyces yeast populations present in the grape must microflora from wineries from different areas around the island of Sicily. Methods and results Yeasts identification was conducted on 2575 colonies isolated from six musts, characterized using Wallerstein Laboratory (WL) nutrient agar, restriction analysis of the amplified 5.8S-internal transcribed spacer region and restriction profiles of amplified 26S rDNA. In those colonies, we identified 11 different yeast species originating from wine musts from two different geographical areas of the island of Sicily. Conclusions We isolated non-Saccharomyces yeasts and described the microflora…
Cytofluorometric detection of wine lactic acid bacteria: application of malolactic fermentation to the monitoring
2012
Abstract In this study we report for the first time a rapid, efficient and cost-effective method for the enumeration of lactic acid bacteria (LAB) in wine. Indeed, up to now, detection of LAB in wine, especially red wine, was not possible. Wines contain debris that cannot be separated from bacteria using flow cytometry (FCM). Furthermore, the dyes tested in previous reports did not allow an efficient staining of bacteria. Using FCM and a combination of BOX/PI dyes, we were able to count bacteria in wines. The study was performed in wine inoculated with Oenococcus oeni (106 CFU ml−1) stained with either FDA or BOX/PI and analyzed by FCM during the malolactic fermentation (MLF). The analysis …
Rapid identification of wine yeast species based on RFLP analysis of the ribosomal internal transcribed spacer (ITS) region
1998
In this study, we identified a total of 33 wine yeast species and strains using the restriction patterns generated from the region spanning the internal transcribed spacers (ITS 1 and 2) and the 5.8S rRNA gene. Polymerase chain reaction (PCR) products of this rDNA region showed a high length variation for the different species. The size of the PCR products and the restriction analyses with three restriction endonucleases (HinfI, CfoI, and HaeIII) yielded a specific restriction pattern for each species with the exception of the corresponding anamorph and teleomorph states, which presented identical patterns. This method was applied to analyze the diversity of wine yeast species during sponta…
Sorption of wine volatile phenols by yeast lees
2005
The capacity of Saccharomyces cerevisiae yeast lees to sorb 4-ethylguaiacol and 4-ethylphenol was investigated in a synthetic medium and in wine. Active dried yeast was more effective when volatile phenols were diluted in red wine. Partition coefficients between wine model solution and wine yeast lees were determined and compared with those measured for dried active yeast. They showed a larger affinity of volatile phenols for wine yeast lees than for dried active yeast. The effect of yeast lees on volatile phenol sorption was sensitive to yeast autolysis level and to physicochemical parameters, such as ethanol content, temperature and pH. These results could be applied in the technology of …
Genomic and Proteomic Analysis of Wine Yeasts
2011
Publisher Summary Saccharomyces cerevisiae is the main microorganism involved in wine fermentation. It has been used as a model organism in molecular biology for many years and is the only wine yeast species for which abundant genomic and proteomic information is available. Most of the techniques currently used in functional genomics and proteomics were initially developed in this yeast. The fact that S. cerevisiae was the first microorganism to be widely used in the development of genome technology allowed other phylogenetically related yeasts to be analyzed subsequently in global sequencing projects, and the use of comparative genomics has since led to important conclusions regarding gene…
Vitamins in wine: Which, what for, and how much?
2021
Vitamins are essential compounds to yeasts, and notably in winemaking contexts. Vitamins are involved in numerous yeast metabolic pathways, including those of amino acids, fatty acids, and alcohols, which suggests their notable implication in fermentation courses, as well as in the development of aromatic compounds in wines. Although they are major components in the course of those microbial processes, their significance and impact have not been extensively studied in the context of winemaking and wine products, as most of the studies focusing on the subject in the past decades have relied on relatively insensitive and imprecise analytical methods. Therefore, this review provides an extensi…
Fermentative stress adaptation of hybrids within the Saccharomyces sensu stricto complex.
2008
Along the fermentation process yeasts are affected by a succession of stress conditions that affect their viability and fermentation efficiency. Among the stress conditions the most relevant are high sugar concentration and low pH in musts, temperature and, as fermentation progresses, ethanol accumulation. Nowadays, due to the demanding nature of modern winemaking practices and sophisticated wine markets, there is an ever-growing search for particular wine yeast strains possessing a wide range of optimized, improved or novel enological characteristics. Traditionally, the species S. cerevisiae and S. bayanus within the Saccharomyces sensu stricto species are considered some of the most impor…
Identification of a yeast strain as a potential stuck wine fermentation restarter: a kinetic characterization
2013
Restarter yeast strains are used to consume residual sugar (mainly fructose) in stuck wine fermentations. Forty-three yeast strains were evaluated initially. Strain ITD-00068 showed the highest values for the maximum growth rate, maximum fructose consumption rate, and maximum ethanol production rate (0.143, 0.268, and 0.231 h−1, respectively). Therefore, it was selected for further molecular and kinetic analyses. RFLP analysis identified this isolate as Saccharomyces cerevisiae. Strain ITD-00068 consumed 100% and 36% of the fructose present (at 20°C and 30°C, respectively), when cultured in medium with 12% (v/v) ethanol. The fructose consumption rate was reduced by 97% at 30°C, when ethanol…
Stress response and expression patterns in wine fermentations of yeast genes induced at the diauxic shift
2000
During wine fermentation yeasts quickly reach a stationary phase, where cells are metabolically active by consuming sugars present in grape must. It is, consequently, of great interest at this stage to identify suitable gene promoters that may be used to induce the expression of genes with enological applications. With this aim, we have studied a group of genes showing an induction peak at the diauxic shift, and possessing stress response elements (STRE) at their promoters. We have determined their induction levels under individualized stress conditions, such as carbon source starvation or high salt concentrations. In all the cases studied, the activation and/or basal transcription are depe…
A comparative study of the wine fermentation performance of Saccharomyces paradoxus under different nitrogen concentrations and glucose/fructose rati…
2010
8 pages, 1 figure, 4 tables.-- Online version published: May 2009.-- The definitive version is available at www3.interscience.wiley.com