0000000000514564
AUTHOR
Cédric Grangeteau
Origines des levures Saccharomyces et non-Saccharomyces présentes dans le moût : Vignoble ou cuverie ?
International audience; Les levures de l’espèce Saccharomyces cerevisiae ont longtemps été considérées comme les seules responsables du processus de fermentation. On sait aujourd’hui que différentes espèces de levures Saccharomyces et non-Saccharomyces (NS) sont présentes dans les moûts et qu’un certain nombre d’entre elles participe à la fermentation alcoolique (FA). Bien qu’il soit aujourd’hui largement admis que les principales sources de levures dans le moût de raisin sont les baies de raisin et le matériel de vinification (Fleet et Heard, 1993 ; Mortimer et Polsinelli, 1999) (figure 1), la part apportée par chacune de ces deux sources est encore mal définie. De plus, d’autres sources p…
Antioxidant Properties of Ergosterol and Its Role in Yeast Resistance to Oxidation
International audience; Although the functions and structural roles of sterols have been the subject of numerous studies, the reasons for the diversity of sterols in the different eukaryotic kingdoms remain unclear. It is thought that the specificity of sterols is linked to unidentified supplementary functions that could enable organisms to be better adapted to their environment. Ergosterol is accumulated by late branching fungi that encounter oxidative perturbations in their interfacial habitats. Here, we investigated the antioxidant properties of ergosterol using in vivo, in vitro, and in silico approaches. The results showed that ergosterol is involved in yeast resistance to tert-butyl h…
Diversity of yeast strains of the genus Hanseniaspora in the winery environment: What is their involvement in grape must fermentation?
Isolated yeast populations of Chardonnay grape must during spontaneous fermentation were compared to those isolated on grape berries and in a winery environment before the arrival of the harvest (air, floor, winery equipment) and in the air through time. Two genera of yeast, Hanseniaspora and Saccharomyces, were isolated in grape must and in the winery environment before the arrival of the harvest but not on grape berries. The genus Hanseniaspora represented 27% of isolates in the must and 35% of isolates in the winery environment. The isolates of these two species were discriminated at the strain level by Fourier transform infrared spectroscopy. The diversity of these strains observed in t…
Method for eliminating microorganisms present in and/or at the surface of a material to be decontaminated
The present invention concems a method for eliminating microorganisms present in and/or at the surface of a material to be decontaminated comprising a step of irradiating said material to be decontaminated with radiation consisting of at least two light beams a1and a2 directed onto said material, the two light beams a1 and a2 respectively having a wavelength λ1 and λ2 of between 380 and 420nm.
Persistence of Two Non-Saccharomyces Yeasts (Hanseniaspora and Starmerella) in the Cellar
International audience; Different genera and/or species of yeasts present on grape berries, in musts and wines are widely described. Nevertheless, the community of non-Saccharomyces yeasts present in the cellar is still given little attention. Thus it is not known if the cellar is a real ecological niche for these yeasts or if it is merely a transient habitat for populations brought in by grape berries during the winemaking period. This study focused on three species of non-Saccharomyces yeasts commonly encountered during vinification: Starmerella bacillaris (synonymy with Candida zemplinina), Hanseniaspora guilliermondii and Hanseniaspora uvarum. More than 1200 isolates were identified at …
A Peptidoglycan-Remodeling Enzyme Is Critical for Bacteroid Differentiation in Bradyrhizobium spp. During Legume Symbiosis.
International audience; In response to the presence of compatible rhizobium bacteria, legumes form symbiotic organs called nodules on their roots. These nodules house nitrogen-fixing bacteroids that are a differentiated form of the rhizobium bacteria. In some legumes, the bacteroid differentiation comprises a dramatic cell enlargement, polyploidization, and other morphological changes. Here, we demonstrate that a peptidoglycan-modifying enzyme in Bradyrhizobium strains, a DD-carboxypeptidase that contains a peptidoglycan-binding SPOR domain, is essential for normal bacteroid differentiation in Aeschynomene species. The corresponding mutants formed bacteroids that are malformed and hypertrop…
FT-IR spectroscopy : A powerful tool for studying the inter- and intraspecific biodiversity of cultivable non-Saccharomyces yeasts isolated from grape must
International audience; The efficiency of the FT-IR technique for studying the inter- and intra biodiversity of cultivable non-Saccharomyces yeasts (NS) present in different must samples was examined. In first, the capacity of the technique FF-IR to study the global diversity of a given sample was compared to the pyrosequencing method, used as a reference technique. Seven different genera (Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Issatchenkia, Metschnikowia and Pichia) were identified by FT-IR and also by pyrosequencing. Thirty-eight other genera were identified by pyrosequencing, but together they represented less than 6% of the average total population of 6 musts. Among the sp…