The presence and load of species of LAB at the end of the malolactic fermentation (MLF) were investigated in 16 wineries from the different Chilean valleys (Limarí, Casablanca, Maipo, Rapel, and Maule Valleys) during 2012 and 2013, using PCR-RFLP and qPCR. Oenococcus oeni was observed in 80% of the samples collected. Dominance of O. oeni was reflected in the bacterial load (O. oeni/total bacteria) measured by qPCR, corresponding to >85% in most of the samples. A total of 178 LAB isolates were identified after sequencing molecular markers, 95 of them corresponded to O. oeni. Further genetic analyses were performed using MLST (7 genes) including 10 commercial strains; the results indicated that commercial strains were grouped together, while autochthonous strains distributed among different genetic clusters. To pre-select some autochthonous O. oeni, these isolates were also characterized based on technological tests such as ethanol tolerance (12 and 15%), SO₂ resistance (0 and 80 mg l⁻¹), and pH (3.1 and 3.6) and malic acid transformation (1.5 and 4 g l⁻¹). For comparison purposes, commercial strain VP41 was also tested. Based on their technological performance, only 3 isolates were selected for further examination (genome analysis) and they were able to reduce malic acid concentration, to grow at low pH 3.1, 15% ethanol and 80 mg l⁻¹ SO₂. The genome analyses of three selected isolates were examined and compared to PSU-1 and VP41 strains to study their potential contribution to the organoleptic properties of the final product. The presence and homology of genes potentially related to aromatic profile were compared among those strains. The results indicated high conservation of malolactic enzyme (>99%) and the absence of some genes related to odor such as phenolic acid decarboxylase, in autochthonous strains. Genomic analysis also revealed that these strains shared 470 genes with VP41 and PSU-1 and that autochthonous strains harbor an interesting number of unique genes (>21). Altogether these results reveal the presence of local strains distinguishable from commercial strains at the genetic/genomic level and also having genomic traits that enforce their potential use as starter cultures.

Oenococcus oeni is part of the microbial terroir involved in wine production. Here, we present three genome sequences of O. oeni strains isolated from spontaneous malolactic fermentation of cultivar Cabernet Sauvignon Maipo Valley, Chile.

Controlling the microorganisms involved in alcoholic fermentation during wine production can be achieved by adding a small quantity of spontaneously fermenting must to freshly crushed grapes, a technique known as pied de cuve (PdC). This method not only serves as an inoculation starter but also enhances the microbial footprint unique to each wine region. Recent studies have confirmed that wines inoculated with PdC exhibit efficient fermentation kinetics comparable to those inoculated with commercial strains of Saccharomyces cerevisiae. However, further research is required to draw robust conclusions about the chemical and sensory impacts of PdC-inoculated wines. In this study, we examined the chemical and sensory effects of the PdC technique across three different harvests: Muscat of Alexandria (Spain, harvests 2022 and 2023) and Sauvignon Blanc (Chile, harvest 2023). Each PdC was prepared using various stressors (sulfur dioxide, ethanol, and temperature). Our findings revealed that wines produced with PdC exhibited similar fermentation kinetics and sensory profiles to those inoculated with commercial strains. Notably, PdC fermentations resulted in lower concentrations of acetic acid compared to both the commercial strain and spontaneous fermentations. The sensory analysis indicated that PdC wines significantly differed from those made with commercial strains, with PdC wines displaying more pronounced tropical notes. These results suggest that the PdC technique, particularly when using specific stressors, can maintain desirable fermentation characteristics while enhancing certain sensory attributes, offering a viable alternative to traditional inoculation methods.

The implementation of vegetative cover crops in vineyards is a sustainable alternative to chemical weed control, potentially influencing both soil fertility and grape-associated microbiota. This study evaluated the impact of six groundcover management strategies under vines—white clover (Trifolium repens), red clover (Trifolium pratense), burr medic (Medicago polymorpha), lupine (Lupinus albus), spontaneous weeds, and an herbicide-treated control—on the microbial dynamics and physicochemical properties of Cabernet Sauvignon must and wine from the Maipo Valley, Chile. Amplicon sequencing of bacterial (16S rRNA) and fungal (ITS) communities was combined with spontaneous fermentation trials and chemical analyses of must and wine. Fungal and bacterial communities on grape surfaces were dominated by Ascomycota and Proteobacteria, respectively, with no significant compositional differences among treatments. During fermentation, Metschnikowia and Tatumella were the most abundant non-Saccharomyces and bacterial genera, respectively, showing dynamic shifts across fermentation stages. Legume-based covers, particularly red clover, increased wine total acidity and polyphenol index while reducing pH. Correlation analyses revealed associations between specific microbial taxa (Metschnikowia, Cohnella, Saliterribacillus) and key enological parameters. Overall, these findings demonstrate that leguminous cover crops subtly modulate vineyard microbial ecology and fermentation outcomes, offering an environmentally sustainable pathway to enhance enological differentiation in semi-arid viticultural regions.

Dry-farmed vineyards of Vitis vinifera L. cv. País in central–southern Chile represent one of the oldest viticultural systems in the Americas; however, objective compositional evidence supporting valley-scale typicity remains limited. This single-vintage study evaluated whether dry-farmed País wines from the Maule and Itata valleys exhibit compositional and sensory differences under standardized winemaking conditions. Ten monovarietal wines (2018 vintage; n = 5 per valley) were produced by controlled microvinification and analysed for general chemistry, phenolic composition, polysaccharides, chromatic attributes (CIELAB), and volatile compounds (SPME–GC–MS), together with descriptive sensory analysis by a trained panel. Total phenols (~1.2 g GAE L⁻¹), anthocyanins (~130 mg malvidin-3-glucoside equivalents L⁻¹), and tannins were low and comparable between valleys. However, differences were observed in specific compositional domains: Maule wines showed higher flavanols, polysaccharides, and aldehydes, whereas Itata wines exhibited higher ester levels. Sensory evaluation revealed differences in colour intensity, floral aroma, retronasal red-fruit notes, and astringency. Multivariate analysis (PCoA) revealed a structured but partial separation between valleys; however, this pattern was not supported by PERMANOVA, indicating limited statistical evidence for multivariate differentiation. These findings, based on a single vintage, suggest subtle compositional and sensory differences rather than strong valley-level typicity.

Climate change is posing a major challenge to the wine industry, with rising alcohol levels emerging as an issue of concern affecting quality, economics and health. This study explores two methods to reduce alcohol content in Chardonnay wines from Chile. Firstly, 5% and 10% of water was added to grape must. Secondly, the sequential inoculation of Metschnikowia pulcherrima with Saccharomyces cerevisiae was examined. The main objectives were to assess the efficacy of these treatments in reducing alcohol levels and their impact on organoleptic properties. Our findings revealed that the presence of M. pulcherrima in winery conditions was less effective in reducing ethanol. Nevertheless, wines resulting from this treatment exhibited an interesting composition with distinct sensory profiles. Furthermore, the Sc-5% W condition displayed promising results by reducing ethanol content by 0.47% (v/v), with less significant changes in the sensory profile. Although the Sc-10% W wines showed a more substantial ethanol reduction of 1.73% (v/v), they exhibited a decreasing trend in volatile compounds and polysaccharides, ultimately being perceived as less complex in sensory analysis and not being preferred by consumers. This research contributes to understanding how these approaches affect the alcohol content and sensory attributes of white wines and is fundamental to the sustainability of the sector and the ability of the sector to recover from climate challenges.