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The main objective of this work was to isolate and characterize viruses that infect both Saccharomyces and other Flor veil-forming genera and suggest the possible consequences they can have on the processes of formation of the Flor veil of typical D.O. Jerez-Xèrés-Sherry wines. Results obtained show that different Flor veil yeast strains isolated in Fino wines and in Amontillados presented a great resistance to ethanol and all of them presented infection by Totiviruses. These were identified after the extraction of double-stranded RNA and amplified by multiplex PCR with specific primers for the most common viruses involved in the killer factor. Subsequently, the same strains of both the S. cerevisiae species and Wickerhamomyces anomalus were subjected to an antiviral treatment with ribavirin. After microbiological analysis with Methylene Blue (MB) plates and by rt-PCR, it was determined that most of them did not show killer factor and the viruses involved in it had been correctly eliminated under the treatment with ribavirin. Subsequently, competition and implantation experiments of the treated and untreated yeasts were carried out against their controls. The wines inoculated with yeasts infected by Totiviruses showed to be dominant in all cases.

Abstract The wines produced in the Jerez-Xérès-Sherry Designation of Origin fall within the category of Fortified Wines, according to Regulation 1308/2013 of the European Parliament, which stipulates that they must be exclusively fortified with wine alcohol, with an acquired alcoholic strength between 95.0% and 96.0%. However, there are other alternative alcohols whose behavior is unknown but could be equally effective in the development of biological aging, with an impact on the final product quality and lower economic costs. This study examines the effect of using malt alcohols, grape pomace, agave, sugarcane, and cereal alcohols, as well as wine alcohols obtained through different distillation methods and at varying alcohol concentrations, for fortifying wines subjected to biological aging. The development of the "flor" yeast veil will be evaluated under each aging condition and isolated and characterized using molecular techniques. Additionally, the base wine fortified with the different alcohols will be monitored and analyzed both physicochemically and organoleptically.

The EC 2019/187 shows the rules for the usage of ethyl alcohols to fortify wines. These must be obtained from products derived from agriculture and the use of alcohols of mineral or chemical origin is not authorized. The ethyl alcohols authorized for the fortification in the D.O. Sherry have wine origin. But, there are other alcohols that could be equally productive and at a lower economic cost, such as beet or sugar cane alcohol. The effect that different types of ethyl alcohols may have on the yeasts of flor remains unknown. Our goal was to analyze the effects of other alcohols (beet, sugar cane, etc.) on the development of the veil of flor. In this way, the yeasts that constitute the veil of flor of Fino wines were isolated and identified by microbiological techniques and characterized by molecular tools and by biochemical and microbiological tests such as cellular hydrophobicity, flocculation, acetic acid production, etc. Then, base wines were fortified with different distilled alcohols, such as malt brandy, tequila, among others. Biological aging under the veil of flor was monitored to later determine the volatile fractions. Alcohol from sugar cane could be a promising alternative to fortify Fino wines.

During alcoholic fermentation, the yeasts responsible for the process produce various metabolites, including urea. The reaction of urea with ethanol spontaneously generates ethyl carbamate in wine, a carcinogenic metabolite whose concentration needs to be regulated. Yeasts produce urea during the arginine metabolic pathway. For this purpose, adaptive evolution has been used by using a toxic analogue of l-arginine, l-canavanine, for selective pressure, once increasing the genetic variability of the population by sporulation and subsequent conjugation. Using this strategy, five putative variants of the parental yeast have been obtained and seem to have reduced urea production, thus being able to achieve a lower concentration of ethyl carbamate.

Vitis vinifera L. ssp. Sylvestris(Gmelin) Hegi is recognized as the dioecious parental generation of today's cultivars. Climatic change and the arrival in Europe of pathogens and pests have led it to be included on the IUCN Red List of Threatened Species in 1997. At best of our knowledge, no studies on microbial populations of grape-berry surfaces have been done. The present work has been focused on the study of yeast occurrence and diversity on grape-berries collected from wild vines. Final outputs have allowed: ito obtain precise information about yeast communities; ii) to provide an objective framework for the classification of the broadest range of species according to their extinction risk; iii) to select attractive yeast strains for their biotechnological potential, offering new opportunities to winemakers. Sampling plan was performed in Azerbaijan, Georgia, Italy, Romania and Spain. In all, 3180 yeast colonies were isolated and identified as belonging to 50 species, including Saccharomyces cerevisiae, by 26S rDNA D1/D2 domains and ITS region sequencing. Isolates of S. cerevisiaewere also analysed by SSR-PCR obtaining 163 different genotypes. This study highlights the biodiversity potential of pristine environments that still represent a fascinating source to face common problems in winemaking.