It is well known that high ethanol levels in wines adversely affect the perception of new wine consumers. Moreover, numerous issues, such as civil restrictions, health risk and trade barriers, are associated with high ethanol concentrations. Several strategies have been proposed to produce wines with lower alcoholic content, one simple and inexpensive approach being the use of new wine native yeasts with less efficiency in sugar to ethanol conversion. Nevertheless, it is also necessary that these yeasts do not impair the quality of wine. In this work, we tested the effect of sequential culture between Hanseniaspora uvarum BHu9 and Saccharomyces cerevisiae BSc114 on ethanol production. Then, the wines produced were analyzed by GC-MS and tested by a sensorial panel. Co-culture had a positive impact on ethanol reduction and sensory profile when compared to the S. cerevisiae monoculture. Wines with lower alcohol content were related to fruity aroma; moreover, color intensity was associated. The wines obtained with S. cerevisiae BSc114 in pure conditions were described by parameters linked with high ethanol levels, such as hotness and astringency. Moreover, floral profile was related to this treatment. Based on these findings, this work provides a contribution to answer the current consumers’ preferences and addresses the main challenges faced by the enological industry.

We propose an alternative GMO based strategy to obtain Saccharomyces cerevisiae mutant strains with a slight reduction in their ability to produce ethanol, but with a moderate impact on the yeast metabolism. Through homologous recombination, two truncated Pdc2p proteins Pdc2pΔ344 and Pdc2pΔ519 were obtained and transformed into haploid and diploid lab yeast strains. In the pdc2Δ344 mutants the DNA-binding and transactivation site of the protein remain intact, whereas in pdc2Δ519 only the DNA-binding site is conserved. Compared to the control, the diploid BY4743pdc2Δ519 mutant strain reduced up to 7.4% the total ethanol content in lab scale-vinifications. The residual sugar and volatile acidity was not significantly affected by this ethanol reduction. Remarkably, we got a much higher ethanol reduction of 10 and 15% when the pdc2Δ519 mutation was tested in a native and a commercial wine yeast strain against their respective controls. Our results demonstrate that the insertion of the pdc2Δ519 mutation in wine yeast strains can reduce the ethanol concentration up to 1.89% (v/v) without affecting the fermentation performance. In contrast to non-GMO based strategies, our approach permits the insertion of the pdc2Δ519 mutation in any locally selected wine strain, making possible to produce quality wines with regional characteristics and lower alcohol content. Thus, we consider our work a valuable contribution to the problem of high ethanol concentration in wine.

The origin terroir provides distinctive characteristics for wines, in relation to soil, climate, oenological practices, etc. Hence, the characterization of each wine region by multiple aspects would allow differentiation of its wines. Several approaches at different scales have studied terroir microbiological fingerprints: from global microbiome analysis up to intraspecific Saccharomyces biodiversity. Mature grapes are the primary source of yeasts, and S. cerevisiae is a key wine fermentative species. Malbec is the emblematic Argentinean variety and is mainly cultivated in the “Zona Alta del Rio Mendoza” (ZARM). In this work, the diversity of S. cerevisiae grape populations was studied at three vintages in two Malbec vineyards of the ZARM, to evaluate their annual diversity and behavior in different vintages. Rarefaction of classical ecological indices was applied for a statistically adequate biodiversity analysis. A total of 654 S. cerevisiae isolates were differentiated by Interdelta-PCR. Each yeast grape population showed a unique composition of S. cerevisiae strains; however, a narrow genetic relationship was found in each vineyard. A slight increase in the initial diversity and a stabilization in the diversity of S. cerevisiae populations were confirmed. These results add to the discussion about the contribution of yeasts to the terroir microbiological concept, and its limitations and stability over the time.

Rhizosphere microorganisms are considered an extension of plants, representing critical actors involved in the promotion of plant nutrient intake from the surrounding environment. Consequently, a great focus is being made on soil microorganisms since they are considered a promising source for crop resilience improvements under a global climate change scenario. To explore bacterial and fungal communities from arid soils in vineyards and their surroundings from two regions with very different climate and tillage histories, an amplicon sequencing analysis was performed. Specifically, Santa Rosa (SR) is in a region commonly known as the first zone, characterised by low altitude (607 m.a.s.l., Winkler V), while Gualtallary (G) is in the Uco Valley Zone, a region with high altitude (1245 m.a.s.l., Winkler III); both in the productive wine region of Mendoza. SR is characterised by its long cultivation history, while G is a recently cultivated region. Topsoil samples were collected and used for bacterial and fungal community profile characterisation. Ascomycota was the predominant phylum (38–97 %) in mycobiome composition, whereas Proteobacteria was the most abundant bacterial phylum (26–34 %) in both regions. Moreover, the main factor explaining microbiome differences between regions was the carbon-to-nitrogen ratio. Anaerolineae and Gammaproteobacteria were a distinctive bacterial class in SR-cultivated soils. Azospirillales were highly abundant in SR uncultivated soils, while Rhizobiales were differentially abundant in G uncultivated soils. Regarding functional analysis, soils from SR showed a higher denitrification activity of nitrifiers as well as glucose-related metabolism, while in G soils, bacterial photosynthesis activities were a differential trait. In addition, Actinobacteria abundance was lower in SR-cultivated soils, indicating a higher susceptibility of this phylum to grapevine crop practices. These results allow the development of hypothetical models of the local microbial resources and their contribution to grapevine nutrition, which is highly important to elaborate recommendations for grapevine management to preserve soil health in vine areas of Mendoza.