Sylvie Dequin

• PhD
• Head of Department at French National Institute for Agriculture, Food, and Environment (INRAE)

Saccharomyces cerevisiae is the yeast of choice for most inoculated wine fermentations worldwide. However, many other yeast species and genera display phenotypes of interest that may help address the environmental and commercial challenges the wine industry has been facing in recent years. This work aimed to provide, for the first time, a systemati...

Dimethyl sulfide (DMS) is a sulfur containing volatile that enhances general fruity aroma and imparts aromatic notes in wine. The most important precursor of DMS is S-methylmethionine (SMM), which is synthesized by grapes and can be metabolized by the yeast S. cerevisiae during wine fermentation. Precursor molecules left after fermentation are chem...

Hybrids between diverged lineages contain novel genetic combinations but an impaired meiosis often makes them evolutionary dead ends. Here, we explore to what extent an aborted meiosis followed by a return-to-growth (RTG) promotes recombination across a panel of 20 Saccharomyces cerevisiae and S. paradoxus diploid hybrids with different genomic str...

Fungal Oligopeptide Transporters (Fot) Fot1, Fot2 and Fot3 have been found in Saccharomyces cerevisiae wine strains, but not in strains from other environments. In the S. cerevisiae wine strain EC1118, Fot1 and Fot2 are responsible for a broader range of oligopeptide utilization in comparison with strains not containing any Fot. This leads to bette...

Hybrids between species or diverged lineages contain fundamentally novel genetic combinations but an impaired meiosis often makes them evolutionary dead ends. Here, we explored to what extent and how an aborted meiosis followed by a return-to-growth (RTG) promotes recombination across a panel of 20 yeast diploid backgrounds with different genomic s...

The mating-type switching endonuclease HO plays a central role in the natural life cycle of Saccharomyces cerevisiae, but its evolutionary origin is unknown. HO is a recent addition to yeast genomes, present in only a few genera close to Saccharomyces. Here we show that HO is structurally and phylogenetically related to a family of unorthodox homin...

The mating-type switching endonuclease HO plays a central role in the natural life cycle of Saccharomyces cerevisiae, but its evolutionary origin is unknown. HO is a recent addition to yeast genomes, present in only a few genera close to Saccharomyces. Here we show that HO is structurally and phylogenetically related to a family of unorthodox homin...

The mating-type switching endonuclease HO plays a central role in the natural life cycle of Saccharomyces cerevisiae, but its evolutionary origin is unknown. HO is a recent addition to yeast genomes, present in only a few genera close to Saccharomyces. Here we show that HO is structurally and phylogenetically related to a family of unorthodox homin...

The yeast Saccharomyces cerevisiae is an attractive industrial microorganism for the production of foods and beverages as well as for various bulk and fine chemicals, such as biofuels or fragrances. Building blocks for these biosyntheses are intermediates of yeast central carbon metabolism (CCM), whose intracellular availability depends on balanced...

The mating-type switching endonuclease HO plays a central role in the natural life cycle of Saccharomyces cerevisiae, but its evolutionary origin is unknown. HO is a recent addition to yeast genomes, present in only a few genera. It resembles a degenerated intein fused to a zinc finger domain. Here we show that HO is structurally and phylogenetical...

Heterologous production of high value chemicals like carotenoids has been performed in several yeasts species and recent advances in synthetic biology and biotechnology allowed spectacular yield improvements. Up to 18 mg / g dry cell weight beta-carotene have been recently reported in S. cerevisiae (1) and even 90 mg / g dry cell weight in the lipo...

Saccharomyces cerevisiae × Saccharomyces kudriavzevii hybrids are typically used for white wine fermentation because of their cryotolerance. One group of these hybrids presents a unique ability to release thiol varietal aroma products as well as excessive amounts of acetic acid under specific conditions, which is detrimental for wine organoleptic q...

Over the last few years, the potential of non-Saccharomyces yeasts to improve the sensory quality of wine has been well recognized. In particular, the use of Starmerella bacillaris in mixed fermentations with Saccharomyces cerevisiae was reported as an appropriate way to enhance glycerol formation and reduce ethanol production. However, during sequ...

We report here the genome sequence of the ascomycetous yeast Torulaspora microellipsoides CLIB 830 T . A reference genome for this species, which has been found as a donor of genetic material in wine strains of Saccharomyces cerevisiae , will undoubtedly give clues to our understanding of horizontal transfer mechanisms between species in the wine e...

Mixed fermentations using a controlled inoculation of Starmerella bacillaris and Saccharomyces cerevisiae starter cultures represent a feasible way to modulate wine composition that takes advantage of both the phenotypic specificities of the non- Saccharomyces strain and the ability of S. cerevisiae to complete wine fermentation. However, according...

The budding yeast Saccharomyces cerevisiae can be found in the wild and is also frequently associated with human activities. Despite recent insights into the phylogeny of this species, much is still unknown about how evolutionary processes related to anthropogenic niches have shaped the genomes and phenotypes of S. cerevisiae. To address this quest...

Background: The volatile metabolites produced by Saccharomyces cerevisiae during alcoholic fermentation, which are mainly esters, higher alcohols and organic acids, play a vital role in the quality and perception of fermented beverages, such as wine. Although the metabolic pathways and genes behind yeast fermentative aroma formation are well descr...

Saccharomyces cerevisiae strains are genetically diverse, largely as a result of human efforts to develop strains specifically adapted to various fermentation processes. These adaptive pressures from various ecological niches have generated behavioral differences among these strains, particularly in terms of their nitrogen consumption capacities. I...

CO2 lost (g/L) during the fermentations processes using the NA, WA, SA, FWI and WE strains. (XLSX)

HPLC results (mg/L) from samples collected during the fermentation processes. (XLSX)

Reciprocal hemizygosity analysis on the TAT2 and DIP5 genes. The YAN consumed is expressed as a percentage based on the amount of nitrogen consumed by the yeasts by the end of fermentation. Mean values and mean standard errors were calculated from three replicates. The SEM is indicated by vertical error bars. Values marked with an asterisk are sign...

Comparisons of the physiological parameters of the five strains. (A) Comparison between the fermentation profiles of the five yeast strains with diverse YAN consumption profiles. The axes show the changes in the specific CO2 production rate with fermentation time on SM465. (B) Comparison between the dry masses of the strains at the end of fermentat...

Nitrogen consumption (mg/L) of the reciprocal hemizygotes for TAT2, DIP5 and RPI1. (XLSX)

Saccharomyces cerevisiaehas been used to perform wine fermentation for several millennia due to its endurance andunmatched qualities. Nevertheless, at the moment of inoculation, wine yeasts must cope with specific stress factors thatstill challenge wine makers by slowing down or compromising the fermentation process. To better assess the role of ge...

Table S1. Summary of the data set obtained during fermentation with 13C valine. Table S2. Summary of the data set obtained during fermentation with 13C leucine. Table S3. Percentage of yeast assimilable nitrogen provided by each nitrogen sources.

Yeast cryotolerance brings some advantages for wine fermentations, including the improved aromatic complexity of white wines. Naturally cold tolerant strains are generally less adept at wine fermentation but fermentative fitness can potentially be improved through hybridization. Here we studied the potential of using hybrids involving Saccharomyces...

Fungi as a Source of Food, Page 1 of 2 Abstract In this article, we review some of the best-studied fungi used as food sources, in particular, the cheese fungi, the truffles, and the fungi used for drink fermentation such as beer, wine, and sake. We discuss their history of consumption by humans and the genomic mechanisms of adaptation during art...

Background During must fermentation thousands of volatile aroma compounds are formed, with higher alcohols, acetate esters and ethyl esters being the main aromatic compounds contributing to floral and fruity aromas. The action of yeast, in particular Saccharomyces cerevisiae, on the must components will build the architecture of the wine flavour an...

Nitrogen and lipids are key nutrients of grape must that influence the production of fermentative aromas by wine yeast, and we have previously shown that a strong interaction exists between these two nutrients. However, more than 90% of the acids and higher alcohols (and their acetate ester derivatives) were derived from intermediates produced by t...

Yeasts from the Saccharomyces complex have been used for millennia for the production of fermented food and alcoholic beverages . The availability of large genomic datasets during the past decade has provided new insights into the genetic and phenotypic diversity, population structure and evolutionary history of these yeasts. Studies of these datas...

p> Aim: In the context of climate change, adaptation of enological practices and implementation of novel techniques are major challenges for winemakers. The potential interventions are linked in particular with the alcohol content and the global acidity of wine. Here, we review current microbiological and technological strategies to overcome such i...

Aim: In the context of climate change, adaptation of enological practices and implementation of novel techniques are major challenges for winemakers. The potential interventions are linked in particular with the alcohol content and the global acidity of wine. Here, we review current microbiological and technological strategies to overcome such issu...

The molecular and evolutionary processes underlying fungal domestication remain largely unknown despite the importance of fungi to bioindustry and for comparative adaptation genomics in eukaryotes. Wine fermentation and biological aging are performed by strains of S. cerevisiae with, respectively, pelagic fermentative growth on glucose, and biofilm...

Importance: A current challenge for the wine industry, in the view of the extensive competition in the worldwide market, is to best meet the consumer expectations regarding the sensory profile of the product while ensuring an efficient fermentation process. Understanding the intracellular fate of the nitrogen sources available in grape juice is es...

Ecology, Diversity and Applications of Saccharomyces Yeasts in Food and Beverages

Flor yeasts of Saccharomyces cerevisiae have been extensively studied for biofilm formation, however the lack of specific haploid model strains has limited the application of genetic approaches such as gene knockout, allelic replacement and Quantitative Trait Locus mapping for the deciphering of the molecular basis of velum formation under biologic...

The most important dogma in white-wine production is the preservation of the wine aroma and the limitation of the oxidative action of oxygen. In contrast, the aging of Sherry and Sherry-like wines is an aerobic process that depends on the oxidative activity of flor strains of Saccharomyces cerevisiae. Under depletion of nitrogen and fermentable car...

Background S. cerevisiae has attracted considerable interest in recent years as a model for ecology and evolutionary biology, revealing a substantial genetic and phenotypic diversity. However, there is a lack of knowledge on the diversity of metabolic networks within this species. Results To identify the metabolic and evolutionary constraints that...

Fermentative aromas play a key role in the organoleptic profile of young wines. Their production depends both on yeast strain and fermentation conditions. A present-day trend in the wine industry consists in developing new strains with aromatic properties using adaptive evolution approaches. An evolved strain, Affinity™ ECA5, overproducing esters,...

Butanediol dehydrogenase (Bdh1p) from Saccharomyces cerevisiae belongs to the superfamily of the medium chain dehydrogenases/reductases and converts reversibly R-acetoin and S-acetoin to (2R,3R)-2,3-butanediol and meso-2,3-butanediol, respectively. It is specific for NAD(H) as a coenzyme and it is the main enzyme involved in the last metabolic step...

In the past decade, horizontal gene transfer (HGT) has emerged as a major evolutionary process that has shaped the genome of Saccharomyces cerevisiae wine yeasts. We recently showed that a large Torulaspora microelliposides genomic island carrying two oligopeptide transporters encoded by FOT genes increases the fitness of wine yeast during fermenta...

Redox homeostasis is a fundamental requirement to the sustainment of metabolism, energy generation and growth in Saccharomyces cerevisiae. Redox cofactors NADH and NADPH are among the most highly connected metabolites in metabolic networks. Changes in their concentrations may induce widespread changes in metabolism. Redox imbalances were achieved h...

The domestication of the wine yeast S. cerevisiae is thought to be contemporary with the development and expansion of viticulture along the Mediterranean basin. Until now, the unavailability of wild lineages prevented the identification of the closest wild relatives of wine yeasts. Here, we enlarge the collection of natural lineages and employ whol...

Saccharomyces cerevisiae and related species, the main workhorses of wine fermentation, have been exposed to stressful conditions for millennia, potentially resulting in adaptive differentiation. As a result, wine yeasts have recently attracted considerable interest for studying the evolutionary effects of domestication. The widespread use of whole...

The maintenance of microbial species in different environmental conditions is associated with adaptive micro-evolutionary changes that are shown here to occur within the descendants of the same strain in comparison with the commercial reference strain. However, scarce information is available regarding changes that occur among strain descendants du...

In South-West of Burkina Faso, palm wine is produced by spontaneous fermentation of the sap from a specific palm tree Borassus akeassii and plays an important role in people's lives. Saccharomyces cerevisiae is the main agent of this alcoholic fermentation but little is known about the diversity of the isolates from palm. In this work, 39 Saccharom...

The increase in phenotypic variability through gene expression noise is proposed to be an evolutionary strategy in selective environments. Differences in promoter-mediated noise between Saccharomyces cerevisiae strains could have been selected for thanks to the benefit conferred by gene expression heterogeneity in the stressful conditions, for inst...

Although an increasing number of horizontal gene transfers (HGTs) have been reported in eukaryotes, experimental evidence for their adaptive value is lacking. Here, we report the recent transfer of a 158-kb genomic region between Torulaspora microellipsoides and Saccharomyces cerevisiae wine yeasts or closely related strains. This genomic region ha...

Although an increasing number of horizontal gene transfers (HGTs) have been reported in eukaryotes, experimental evidence for their adaptive value is lacking. Here, we report the recent transfer of a 158-kb genomic region between Torulaspora microellipsoides and Saccharomyces cerevisiae wine yeasts or closely related strains. This genomic region ha...

Comment la nutrition azotée influe-t-elle sur la production d'arômes?

Ce numéro d’Innovations Agronomiques rassemble les présentations du colloque « la biodiversité des ferments au service de l’innovation » qui s'est tenu à Paris le 25 juin 2015.

Des avancées dans le développement de levures à faible rendement en alcool

Impact des ajouts de nutriments sur les arômes fermentaires

The yeast Saccharomyces cerevisiae is one of the most important microorganisms for food and drink production and it is as well a model for biology. Surprisingly, the bases of yeast population structure have been unraveled only recently [1, 2] and the first genomic population approaches have failed to point adaptation to ecological niches. However,...

Volatile compounds produced by yeast during fermentation greatly influence the organoleptic qualities of wine. We developed a model to predict the combined effects of initial nitrogen and phytosterol content and fermentation temperature on the production of volatile compounds. We used a Box-Behnken design and response surface modeling to study the...

Background Under N-limiting conditions, Saccharomyces cerevisiae strains display a substantial variability in their biomass yield from consumed nitrogen -in particular wine yeasts exhibit high growth abilities- that is correlated with their capacity to complete alcoholic fermentation, a trait of interest for fermented beverages industries. The aim...

Background Under N-limiting conditions, Saccharomyces cerevisiae strains display a substantial variability in their biomass yield from consumed nitrogen -in particular wine yeasts exhibit high growth abilities- that is correlated with their capacity to complete alcoholic fermentation, a trait of interest for fermented beverages industries. The aim...

We performed a dynamic and quantitative analysis of the synthesis of fermentative aromas by an aromatic wine yeast (ECA5) obtained by adaptive evolution. During fermentation at pilot scale on synthetic and natural musts, ECA5 produced volatile compounds (higher alcohols and their acetates, ethyl esters) at higher rates than the ancestral strain, wi...

There is a strong demand from the wine industry for methodologies to reduce the alcohol content of wine without compromising wine sensory characteristics. We assessed the potential of adaptive laboratory evolution strategies under hyperosmotic stress for generating Saccharomyces cerevisiae wine yeast strains with enhanced glycerol and reduced ethan...

The ascomycetous yeast Zygosaccharomyces bailii is one of the most problematic spoilage yeasts in food and beverage industries, due to its exceptional resistance to various stresses. A better understanding of the molecular mechanisms underlying these stress resistance phenotypes might help develop strategies to improve food quality. Thus, we determ...

Using an evolutionary engineering strategy based on long-term batch cultivation on gluconate, a substrate metabolized by the PP pathway, we obtained wine yeast strains which have evolved a higher capacity to grow on gluconate (Cadiere, et al., 2011, Metab Eng 13:263-71). Using 13C flux analysis, we showed that the evolved wine yeast strain exhibits...

Saccharomyces cerevisiae strains from diverse natural habitats harbour a vast amount of phenotypic diversity, driven by interactions between yeast and the respective environment. In grape juice fermentations, strains are exposed to a wide array of biotic and abiotic stressors, which may lead to strain selection and generate naturally arising strain...

PCA representation of the three strain clusters, obtained with k-means clustering algorithm. The symbols represent the belonging of the 172 strains shown in the phenotypic data PCA (Figure 2b) to each cluster: circles – cluster 1 (38 strains); lines – cluster 2 (90 strains); squares – cluster 3 (44 strains). (TIF)

Origin and technological application of the 172 Saccharomyces cerevisiae strains. (DOCX)

Phenotypic variation of 172 strains under 30 growth conditions. Strains are organized according to UPGMA-based hierarchical clustering (cophenetic correlation factor = 0.75), using Euclidean distance correlation to estimate phenotypic profile similarities. Symbols represents the strains technological applications or origin: black star – wine and vi...

(XLSX)

Stuck fermentation is a major problem in winemaking, resulting in large losses in the wine industry. Specific starter yeasts are used to restart stuck fermentations in conditions determined essentially on the basis of empirical know-how. We have developed a model synthetic stuck wine and an industrial process-based procedure for restarting fermenta...

The efficiency of nitrogen use is a key determinant of the completion of alcoholic fermentation. We analyzed the kinetics of consumption of 18 nitrogen compounds by 14 Saccharomyces cerevisiae strains of various origins in a synthetic medium that mimicked a grape must. The kinetic profiles of total nitrogen consumption were diverse, but the order o...

Background: Redox homeostasis is essential to sustain metabolism and growth. We recently reported that yeast cells meet a gradual increase in imposed NADPH demand by progressively increasing flux through the pentose phosphate (PP) and acetate pathways and by exchanging NADH for NADPH in the cytosol, via a transhydrogenase-like cycle. Here, we stud...

13 C-flux analysis:S. cerevisiae metabolic network, flux distribution in response to acetoin additions (0, 100, 200, 300 mM) and measured SFL and experimental data. (A) Reactions of the metabolic network used for 13 C-flux analysis. (B) Fluxes estimated by 13 C-flux analysis. (C) Measured SFL. (D) Specific growth rate, glucose uptake rates and yiel...

Differentially expressed genes involved in the response to increases in NADPH and NADH oxidation. The differentially expressed genes involved in the response to increases in the oxidation of NADPH (100, 200 and 300 mM acetoin) and NADH (200 mM acetoin) are shown.

Controlling the amounts of redox cofactors to manipulate metabolic fluxes is emerging as a useful approach to optimizing byproduct yields in yeast biotechnological processes. Redox cofactors are extensively interconnected metabolites, so predicting metabolite patterns is challenging and requires in-depth knowledge of how the metabolic network respo...

Comparison of the one-way ANOVAs and Kruskal-Wallis tests for the phenotypic variables. (PDF)

Fermentation profile as a phenotypic fingerprint. (PDF)

Analysis of the phenotypic traits of the 72 S. cerevisiae strains regarding to their habitat. (PDF)

Strain origin-dependent characterization of S. cerevisiae population on the basis of phenotypes. (PDF)

Intra-class correlation coefficient (ICC) of the 21 strains which have been grown under wine fermentation conditions at least in duplicate. (PDF)

Correlation analysis between the 18 phenotypic traits within the population of 72 stains. (PDF)