Enhancing wine malolactic fermentation: Variable effect of yeast mannoproteins on Oenococcus oeni strains.

Lactic acid bacteria (LAB), principally Oenococcus oeni, play crucial roles in wine production, contributing to the transformation of L-malic acid into L-lactic acid during malolactic fermentation (MLF). This fermentation is influenced by different factors, including the initial LAB population and wine stress factors, such as nutrient availability. Yeast mannoproteins can enhance LAB survival in wine.

The Impact of the Inoculation of Different on the Chemical and Organoleptic Profiles of Wines.

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 (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 .

Influence of different stress factors during the elaboration of grape must's pieddecuve on the dynamics of yeast populations during alcoholic fermentation.

The pieddecuve (PdC) technique involves using a portion of grape must to undergo spontaneous fermentation, which is then used to inoculate a larger volume of must. This allows for promoting autochthonous yeasts present in the must, which can respect the typicality of the resulting wine. However, the real impact of this practice on the yeast population has not been properly evaluated.

Simultaneous Analysis of Organic Acids, Glycerol and Phenolic Acids in Wines Using Gas Chromatography-Mass Spectrometry.

Fermented beverages, particularly wines, exhibit variable concentrations of organic and phenolic acids, posing challenges in their accurate determination. Traditionally, enzymatic methods or chromatographic analyses, mainly high-performance liquid chromatography (HPLC), have been employed to quantify these compounds individually in the grape must or wine. However, chromatographic analyses face limitations due to the high sugar content in the grape must.

Comparative study of inoculation strategies of Torulaspora delbrueckii and Saccharomyces cerevisiae on the performance of alcoholic and malolactic fermentations in an optimized synthetic grape must.

Progress in oenological biotechnology now makes it possible to control alcoholic (AF) and malolactic (MLF) fermentation processes for the production of wines. Key factors in controlling these processes and enhancing wine quality include the use of selected strains of non-Saccharomyces species, Saccharomyces cerevisiae, and Oenococcus oeni, as well as the method of inoculation (co-inoculation or sequential) and the timing of inoculation. In the present work, we investigated the effects of different inoculation strategies of two Torulaspora delbrueckii (Td-V and Td-P) strains followed by S.

Succinic acid production by wine yeasts and the influence of GABA and glutamic acid.

As a consequence of alcoholic fermentation (AF) in wine, several compounds are released by yeasts, and some of them are linked to the general quality and mouthfeel perceptions in wine. However, others, such as succinic acid, act as inhibitors, mainly of malolactic fermentation. Succinic acid is produced by non-Saccharomyces and Saccharomyces yeasts during the initial stages of AF, and the presence of some amino acids such as γ-aminobutyric acid (GABA) and glutamic acid can increase the concentration of succinic acid.

The yeast mRNA-binding protein Cth2 post-transcriptionally modulates ergosterol biosynthesis in response to iron deficiency.

Sterol synthesis is an iron-dependent metabolic pathway in eukaryotes. Consequently, fungal ergosterol biosynthesis (ERG) is down-regulated in response to iron deficiency. In this report, we show that, upon iron limitation or overexpression of the iron-regulated mRNA-binding protein Cth2, the yeast Saccharomyces cerevisiae down-regulates the three initial enzymatic steps of ergosterol synthesis (ERG1, ERG7 and ERG11).

The use of Torulaspora delbrueckii to improve malolactic fermentation.

The potential use of Torulaspora delbrueckii as a starter culture for wine alcoholic fermentation has become a subject of interest in oenological research. The use of this non-Saccharomyces yeast can modulate different wine attributes, such as aromatic substances, organic acids and phenolic compound compositions. Thus, the obtained wines are different from those fermented with Saccharomyces cerevisiae as the sole starter.

Screening of Saccharomyces cerevisiae and Torulaspora delbrueckii strains in relation to their effect on malolactic fermentation.

The use of Torulaspora delbrueckii in the alcoholic fermentation (AF) of grape must is increasingly studied and used in the wine industry. In addition to the organoleptic improvement of wines, the synergy of this yeast species with the lactic acid bacterium Oenococcus oeni is an interesting field of study. In this work, 60 strain combinations were compared: 3 strains of Saccharomyces cerevisiae (Sc) and 4 strains of Torulaspora delbrueckii (Td) in sequential AF, and four strains of O.

Impact of rare yeasts in Saccharomyces cerevisiae wine fermentation performance: Population prevalence and growth phenotype of Cyberlindnera fabianii, Kazachstania unispora, and Naganishia globosa.

Saccharomyces cerevisiae is a highly fermentative species able to complete the wine fermentation. However, the interaction with other non-Saccharomyces yeasts can determine the fermentation performance of S. cerevisiae.

Transcriptional regulation of ergosterol biosynthesis genes in response to iron deficiency.

Iron participates as an essential cofactor in the biosynthesis of critical cellular components, including DNA, proteins and lipids. The ergosterol biosynthetic pathway, which is an important target of antifungal treatments, depends on iron in four enzymatic steps. Our results in the model yeast Saccharomyces cerevisiae show that the expression of ergosterol biosynthesis (ERG) genes is tightly modulated by iron availability probably through the iron-dependent variation of sterol and heme levels.

Differentiation of Saccharomyces species by lipid and metabolome profiles from a single colony.

Yeast metabolism depends on growing conditions, which include the chemical composition of the medium, temperature and growth time. Historically, fatty acid profiles have been used to differentiate yeasts growing in liquid media. The present study determined the fatty acids of Saccharomyces species in colonies.

Molecular adaptation response of Oenococcus oeni in non-Saccharomyces fermented wines: A comparative multi-omics approach.

Oenococcus oeni is the main agent responsible for malolactic fermentation (MLF) in wine. This usually takes place in red wines after alcoholic fermentation (AF) carried out by Saccharomyces cerevisiae. In recent years, there is an increasing interest in using non-Saccharomyces yeast, usually in combination with S.

Sterol Composition Modulates the Response of to Iron Deficiency.

Iron is a vital micronutrient that functions as an essential cofactor in multiple biological processes, including oxygen transport, cellular respiration, and metabolic pathways, such as sterol biosynthesis. However, its low bioavailability at physiological pH frequently leads to nutritional iron deficiency. The yeast is extensively used to study iron and lipid metabolisms, as well as in multiple biotechnological applications.

Use of Yeast Mannoproteins by during Malolactic Fermentation under Different Oenological Conditions.

is the main agent of malolactic fermentation in wine. This fermentation takes place after alcoholic fermentation, in a low nutrient medium where ethanol and other inhibitor compounds are present. In addition, some yeast-derived compounds such as mannoproteins can be stimulatory for .

Simulated lees of different yeast species modify the performance of malolactic fermentation by Oenococcus oeni in wine-like medium.

The use of non-Saccharomyces yeast together with S. cerevisiae in winemaking is a current trend. Apart from the organoleptic modulation of the wine, the composition of the resulting yeast lees is different and may thus impact malolactic fermentation (MLF).

Thermo-adaptive evolution to generate improved Saccharomyces cerevisiae strains for cocoa pulp fermentations.

Cocoa pulp fermentation is a consequence of the succession of indigenous yeasts, lactic acid bacteria and acetic acid bacteria that not only produce a diversity of metabolites, but also cause the production of flavour precursors. However, as such spontaneous fermentations are less reproducible and contribute to produce variability, interest in a microbial starter culture is growing that could be used to inoculate cocoa pulp fermentations. This study aimed to generate robust S.

Impact of changes in wine composition produced by non-Saccharomyces on malolactic fermentation.

Non-Saccharomyces yeasts have increasingly been used in vinification recently. This is particularly true of Torulaspora delbrueckii and Metschnikowia pulcherrima, which are inoculated before S. cerevisiae, to complete a sequential alcoholic fermentation.

Oxygen consumption rate of lees during sparkling wine (Cava) aging; influence of the aging time.

Sparkling wines elaborated with a traditional method need to age in the bottle in contact with wine lees because yeast autolysis enriches the wines in colloids and improves their effervescence, foam and aromatic complexity. It is generally considered that lees protect the wine against oxidation because they consume small amounts of oxygen that can permeate the crown cap. However, to our knowledge there is no specific study on this subject using lees from real sparkling wine.

Basal catalase activity and high glutathione levels influence the performance of non-Saccharomyces active dry wine yeasts.

Non-Saccharomyces wine yeasts are useful tools for producing wines with complex aromas or low ethanol content. Their use in wine would benefit from their production as active dry yeast (ADY) starters to be used as co-inocula alongside S. cerevisiae.

The lipid composition of yeast cells modulates the response to iron deficiency.

Iron is a vital micronutrient for all eukaryotes because it participates as a redox cofactor in multiple metabolic pathways, including lipid biosynthesis. In response to iron deficiency, the Saccharomyces cerevisiae iron-responsive transcription factor Aft1 accumulates in the nucleus and activates a set of genes that promote iron acquisition at the cell surface. In this study, we report that yeast cells lacking the transcription factor Mga2, which promotes the expression of the iron-dependent Δ9-fatty acid desaturase Ole1, display a defect in the activation of the iron regulon during the adaptation to iron limitation.

Occurrence and enological properties of two new non-conventional yeasts (Nakazawaea ishiwadae and Lodderomyces elongisporus) in wine fermentations.

The microbial diversity of wine alcoholic fermentation is not restricted to the presence and activity of Saccharomyces yeast strains. Some non-Saccharomyces species have been described as part of the fermentative microbiota, specially found in the initial steps of wine fermentations. These species may play roles from wine spoilage to flavor quality enhancement.

Metabolism of Schizosaccharomyces pombe under reduced osmotic stress conditions afforded by fed-batch alcoholic fermentation of white grape must.

Strains of Schizosaccharomyces pombe are being increasingly investigated with regards to their grape winemaking potential either in combination with the typical production yeast, Saccharomyces cerevisiae, or in monoseptic fermentations. Their ethanol tolerance and ability to degrade L-malic acid is oenologically convenient but contrasts with the comparatively high acetic acid and acetaldehyde formation potential which is considered undesirable, especially in white winemaking. The purpose of this work was to investigate the performance of a selected S.