Jean-Luc Legras

French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · UMR1083 Sciences Pour l'Oenologie (SPO)

A bstract Next generation sequencing offers several ways to study microbial communities. For agri-food sciences, identifying species in diverse food ecosystems is key for both food sustainability and food security. The aim of this study was to compare metabarcoding pipelines and markers to determine fungal diversity in food ecosystems, from Illumin...

Here, we report the draft genome sequence and annotation of the yeast Candida railenensis strain CLIB 1423. The assembly consists of 57 nuclear scaffolds and 1 complete mitochondrial chromosome, for a total of 13.8 Mb ( N 50 , 0.54 Mb; L 50 , 9). The annotation contains 6,013 coding DNA sequences (CDSs) (BUSCO completeness, 99.6%).

The world is full of an amazing microbial abundance and diversity. Microorganisms are part of all ecosystems and contribute to the activities of nature. Human beings have been studying and harnessing microbial properties for centuries and, nowadays, microorganisms are applied in numerous industrial, agricultural, environmental, and biotechnological...

Sterols are a fraction of the eukaryotic lipidome that is essential for the maintenance of cell membrane integrity and its good functionality. During alcoholic fermentation, they enhance yeast growth, metabolism and viability, as well as resistance to high sugar content and ethanol stress. Grape musts clarified in excess lead to the loss of solid p...

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...

Responsible for plasma membrane structure maintenance in eukaryotic organisms, sterols are essential for yeast development. The role of two sterol sources in Saccharomyces cerevisiae during wine fermentation is highlighted in this review: ergosterol (yeast sterol produced by yeast cells under aerobic conditions) and phytosterols (plant sterols impo...

Geotrichum candidum is an environmental yeast, also found as part of the cheese surface microbiota, where it is important in the ripening of many traditional cheeses, such as Camembert. We have previously developed a Multi Locus Sequence Typing (MLST) scheme, which differentiated five clades, of which one contained only environmental isolates, two...

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...

Hydrogen sulfide (H2S) is the main volatile sulfur compound produced by Saccharomyces cerevisiae during alcoholic fermentation and its overproduction leads to poor wine sensory profiles. Several factors modulate H2S production and winemakers and researchers require an easy quantitative tool to quantify their impact. In this work, we developed a new...

A total of 296 isolates of Saccharomyces cerevisiae sampled from naturally fermenting grape musts from various locations in Lebanon were typed by interdelta fingerprinting. Of these, 88 isolates were compared with oenological strains originating from various countries, using microsatellite characterization at six polymorphic loci. These approaches...

Sterols are essential components of the yeast membrane and their synthesis requires oxygen. Yet, Saccharomyces cerevisiae has developed the ability to take up sterols from the medium under anaerobiosis. Here we investigated sterol uptake efficiency and the expression of genes related to sterol import in Saccharomyces and non-Saccharomyces wine yeas...

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...

Microbial ecology is an integral part of an agricultural ecosystem and influences the quality of agricultural commodities. Microbial activity influences grapevine health and crop production, conversion of sugar to ethanol during fermentation, thus forming wine aroma and flavour. There are regionally differentiated microbial patterns in grapevines a...

Saccharomyces cerevisiae is the main actor of wine fermentation but at present, still little is known about the factors impacting its distribution in the vineyards. In this study, 23 vineyards and 7 cellars were sampled over 2 consecutive years in the Bordeaux and Bergerac regions. The impact of geography and farming system and the relation between...

Microbial activity is an integral part of an agricultural ecosystem and influences the quality of agricultural commodities. Microbial ecology influences grapevine health and crop production, conversion of sugar to ethanol during fermentation, thus wine aroma and flavour. There are regionally differentiated microbial patterns in grapevines and must...

Winemakers are increasingly keen to limit the use of commercial yeasts in order to reduce oenological inputs. The preparation of an indigenous winery-made fermentation starter from grapes called ‘pied de cuve’ (PdC) is becoming popular, especially in organic farming systems. However, the implementation of the PdC method is still empirical and knowl...

Chromosomal rearrangements (CR) such as translocations, duplications and inversions play a decisive role in the adaptation of microorganisms to specific environments. In enological Saccharomyces cerevisiae strains, CR involving the promoter region of the gene SSU1 lead to a higher sulfite tolerance by enhancing the SO2 efflux. To date, three differ...

Chromosomal rearrangements (CR) such as translocations, duplications and inversions play a decisive role in the adaptation of microorganisms to specific environments. In enological Saccharomyces cerevisiae strains, CR involving the promoter region of the gene SSU1 lead to a higher sulfite tolerance by enhancing the SO2 efflux. To date, three differ...

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...

Hanseniaspora, a predominant yeast genus of grape musts, includes sister species recently reported as fast evolving. The aim of this study was to investigate the genetic relationships between the four most closely related species, at the population level. A multi-locus sequence typing strategy based on five markers was applied on 107 strains, confi...

Multiple studies have revealed the richness of the fungal microbial community of grape must and wine which are under the influence of environmental and anthropogenic factors. However, until recently, we had no evidence of how historical processes may have impacted the diversity of the yeasts found on grapes and developing during wine alcoholic ferm...

In grape must, nitrogen content is often insufficient for the completion of alcoholic fermentation by yeast. For Saccharomyces cerevisiae, response to nitrogen deficiency is strain-dependent, some strains being able to complete fermentation despite nitrogen deficiency whereas others are not and result in sluggish or stuck fermentation. Thus, it is...

Multiple studies have revealed the richness of the fungal microbial community of grape must and wine which are under the influence of environmental and anthropogenic factors. However, until recently, we had no evidence of how historical processes may have impacted the diversity of the yeasts found on grapes and developing during wine alcoholic ferm...

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...

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...

From yeast diversity to yeast domestication. 45. Conference on Yeast

With the development of organic wines and ciders, there is a real tendency to carry out spontaneous fermentations, which involve the development of indigenous yeasts and bacteria. Indeed, these microorganisms are sometimes considered as components of the terroir that participate in the typicity of wines and ciders. However, no scientific knowledge...

Saccharomyces cerevisiae is a common yeast with several applications, among which the most ancient is winemaking. Because individuals belonging to this species show a wide genetic and phenotypic variability, the possibility to identify the strains driving fermentation is pivotal when aiming at stable and palatable products. Metagenomic sequencing i...

Hanseniaspora yeasts are predominant species on wine grapes and consequently in grape musts where they contribute to the development of wine aroma. The most frequent species H. guilliermondii, H. opuntiae and H. uvarum are particularly close genetically; the D1D2 region of their ribosomal subunits differs by less than 4 nucleotides. Our first objec...

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...

Dendrogram obtained by mtDNA RFLP of the strains considered in the survey. The analysis was determined by the UPMGA method and performed by Dice similarity coefficient.

Neighbor net showing the clustering of 258 yeast strains isolated from different sources. The network was constructed from Bruvo's distance between strains based on the polymorphism at 18 loci. The names of the strains coming from our isolation programs are in black, and the 4 strains whose genome has been sequenced in pink. Branches of wine strain...

Loadings of the different sampling site to the axis of SPCA.

Simultaneous plot of neighbor joining dendrograms obtained from each typing methods Microsatellite typing or mDNA RFLP after calculation of dissimilarity distance matrix between strains for each method.

Strains tested in this study.

Microsatellite loci description and primers.

Genotypes scored for each strain.

Neighbour Joining tree presenting the differentiation of the different populations sampled in the three appellation areas measured by Fst (red PAO area, Brown LPAO area CVPAO area).

Weir and Cochran (1984) pairwise Fst between sampling areas and significance, calculated with Fstat. Pairwise Fst values are given in the lower triangular matrix and estimated p-values are given in the upper triangular matrix. Significance after correction of multiple tests at the 5% nominal level is indicated in bold (upper triangular matrix). NA:...

In recent years the interest for natural fermentations has been re-evaluated in terms of increasing the wine terroir and managing more sustainable winemaking practices. Therefore the level of yeast genetic variability and the abundance of Saccharomyces cerevisiae native populations in vineyard are becoming more and more crucial at both ecological a...

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...

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...

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

The physicochemical properties of the wine pigments catechyl-pyranomalvidin-3-O-glucoside (PA1) and guaiacyl-pyranomalvidin-3-O-glucoside (PA2) are extensively revisited using ultraviolet (UV)-visible spectroscopy, dynamic light scattering (DLS) and quantum chemistry density functional theory (DFT) calculations. In mildly acidic aqueous solution, e...

In the past, the galactose-negative (Gal(-)) phenotype was a key physiological character used to distinguish Saccharomyces bayanus from S. cerevisiae In this work, we investigated the inactivation of GAL gene networks in S. bayanus, which is an S. uvarum/S. eubayanus hybrid, and in S. cerevisiae wine strains erroneously labelled "S. bayanus". We ma...

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...

Unlabelled: Palm wine produced traditionally and consumed by many people in the South-West of Burkina Faso is subject to alteration. In this study, we carried out a follow-up of two palm wines' fermentation during the 10 days in which palm wines are classically produced and consumed. We monitored biochemical characteristics of fermenting wines as...

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...

Three wine estates were sampled in Sauternes, a typical appellation of Bordeaux wine area producing sweet white wine. Over those wine estates, 551 yeasts strains were collected between 2012 and 2014 adding 102 older strains from 1992 to 2011 from wine estate C. All strains were analyzed through 15 microsatellites markers resulting in 503 unique Sac...

Considered as a sister species of Saccharomyces cerevisiae, Saccharomyces uvarum is, to a lesser extent, an interesting species for fundamental and applied research studies. Despite its potential interest as a new gene pool for fermenting agents, the intraspecific molecular genetic diversity of this species is still poorly investigated. In this stu...

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...

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...