Identification and Molecular Characterization of Novel Mycoviruses in Saccharomyces and Non-Saccharomyces Yeasts of Oenological Interest

Wine yeasts can be natural hosts for dsRNA, ssRNA viruses and retrotransposon elements. In this study, high-throughput RNA sequencing combined with bioinformatic analyses unveiled the virome associated to 16 Saccharomyces cerevisiae and 8 non-Saccharomyces strains of oenological interest. Results showed the presence of six viruses and two satellite dsRNAs from four different families, two of which—Partitiviridae and Mitoviridae—were not reported before in yeasts, as well as two ORFan contigs of viral origin. According to phylogenetic analysis, four new putative mycoviruses distributed in Totivirus, Cryspovirus, and Mitovirus genera were identified. The majority of commercial S. cerevisiae strains were confirmed to be the host for helper L-A type totiviruses and satellite M dsRNAs associated with the killer phenotype, both in single and mixed infections with L-BC totiviruses, and two viral sequences belonging to a new cryspovirus putative species discovered here for the first time. Moreover, single infection by a narnavirus 20S-related sequence was also found in one S. cerevisiae strain. Considering the non-Saccharomyces yeasts, Starmerella bacillaris hosted four RNAs of viral origin—two clustering in Totivirus and Mitovirus genera, and two ORFans with putative satellite behavior. This study confirmed the infection of wine yeasts by viruses associated with useful technological characteristics and demonstrated the presence of complex mixed infections with unpredictable biological effects.

Wine Yeasts 1.0

The conversion of grape juice into wine is a complex biochemical process involving alcoholic fermentation, production of wide range of metabolites and interactions of yeast strains, bacteria and fungi [...]

Improvments in the technology of locally produced sparkling wines

Систематизированы современные литературные данные о направлениях повышения качества отечественных игристых вин. Для увеличения выхода сусла рекомендовано использование пневматических мембранных прессов. Установлено, что использование мембранного пресса «Diemme Velvet 150» позволяет увеличить выход качественных фракций сусла до 68,2 дал/т. При повышении выхода сусла из 1 т винограда в получаемых виноматериалах происходит увеличение концентраций галловой, сиреневой, кафтаровой, каутаровой кислот, (+) - эпикатехина, кверцитина, кверцитин-3-0-гликозида, процианидинов, полимерных флаваноидов при одновременном снижении концентрации (+) - Д-катехина. Разработан многокритериальный показатель контроля качества виноматериалов, полученных из сусла при различном его выходе из 1 т винограда. Установлено, что лучшими по пенистым свойствам, ароматобразующему комплексу и органолептической оценке являются сортовые виноматериалы Каберне-Совиньон и Рубиновый Магарача, приготовленные с использованием штамма дрожжей 47-К. Приведены оптимальные технологические схемы обработок виноматериалов для белых игристых вин. Сделан вывод о том, что сахаросодержащие компоненты виноградного происхождения целесообразно применять вместо тиражного ликера для повышения качества игристых вин. Установлена корреляция между массовой концентрацией полимерных форм фенольных веществ и значением показателя максимального объема пены (V): для розовых игристых вин - 0,777, для красных игристых вин - 0,834. С целью повышения качества игристых вин рекомендуется применение автолизатов винных дрожжей, полученных на установке ВА-0,6 для кавитационной обработки дрожжевой массы. Приведен перечень разработанных и утвержденных СТО (стандартов организации) для определения специфических показателей при производстве игристых вин. Present-day literature data on the directions of improving the quality of locally produced sparkling wines are systematized. To increase the must yield, using of pneumatic membrane pressing machines is recommended. It has been established that using of membrane pressing machine Diemme Velvet 150 allows increasing the yield of high-quality must fractions to 68.2 daL/t. With an increase in the yield of must per 1 ton of grapes, an increase in the concentrations of gallic, lilac, caftaric, cautaric acids, (+) - epicatechin, quercitin, quercitin-3-0-glycoside, procyanidins, polymer flavonoids with simultaneous decrease in the concentration of (+) - D-catechin in the resulting base wine is observed. A quality control multi-criteria indicator of base wines obtained from must at its different output per 1 ton of grapes was developed. It was established that varietal base wines of ‘Cabernet-Sauvignon’ and ‘Rubynovyi Magaracha’, prepared using the 47-K yeast strain, are the best in terms of foaming capacity, aroma-producing complex and organoleptic evaluation. The optimal technological schemes of base wine processing are presented for white sparkling wines. It is advisable to use sugar-containing components of grape origin instead of tirage liqueur to improve the quality of sparkling wines. A correlation between the mass concentration of polymeric forms of phenolic substances and the value of maximum foam volume indicator (V) was established: for rose sparkling wines - 0.777, for red sparkling wines - 0.834. In order to improve the quality of sparkling wines, it is recommended to use autolysed wine yeasts obtained at the VA-0.6 unit for yeast mass cavitation treatment. A list of developed and approved STOs (standards of organizations) for determining specific indicators in the production of sparkling wines is given.

Effects of different vinification technologies and yeasts on qualitative parameters and terpene compounds of Sauvignon Blanc wines

Sauvignon Blanc represents an important grape variety. The wine made from this variety is known to have a wide range of aroma profiles from nettles to tropical fruits. Beside the raw material quality (grapes), the quality of wines can be fundamentally influenced by the technological conditions applied in the wine making process. Yeast and other microorganisms play a key role in the formation of metabolites during alcoholic fermentation. In this study, the effects of autochthonous or selected wine yeasts (Saccharomyces cerevisiae) and fermentation temperatures (15 °C and 19 °C) were tested on major monoterpenes contents of wines during the period 2016–2017. The obtained values show that the highest contents of linalool (24.36 μg L−1) and hotrienol (11.84 μg L−1) were determined in wine samples produced with active (selected) wine yeast at lower temperature. Sensory evaluation results indicated that monoterpenes can have a positive effect on the overall sensory quality of Sauvignon Blanc wines, despite the fact that their determined concentrations in the evaluated samples were not higher than their threshold values.

Mechanisms Involved in Interspecific Communication between Wine Yeasts

In parallel with the development of non-Saccharomyces starter cultures in oenology, a growing interest has developed around the interactions between the microorganisms involved in the transformation of grape must into wine. Nowadays, it is widely accepted that the outcome of a fermentation process involving two or more inoculated yeast species will be different from the weighted average of the corresponding individual cultures. Interspecific interactions between wine yeasts take place on several levels, including interference competition, exploitation competition, exchange of metabolic intermediates, and others. Some interactions could be a simple consequence of each yeast running its own metabolic programme in a context where metabolic intermediates and end products from other yeasts are present. However, there are clear indications, in some cases, of specific recognition between interacting yeasts. In this article we discuss the mechanisms that may be involved in the communication between wine yeasts during alcoholic fermentation.

Nitrogenous Compound Utilization and Production of Volatile Organic Compounds among Commercial Wine Yeasts Highlight Strain-Specific Metabolic Diversity

Saccharomyces cerevisiae is widely used in grape juice fermentation to produce wines. Along with the genetic background, the nitrogen in the environment in which S. cerevisiae grows impacts its regulation of metabolism.