Antioxidant Properties of Ergosterol and Its Role in Yeast Resistance to Oxidation.

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.

A leguminous species exploiting alpha- and beta-rhizobia for adaptation to ultramafic and volcano-sedimentary soils: an endemic Acacia spirorbis model from New Caledonia.

Acacia spirorbis subsp. spirorbis Labill. is a widespread tree legume endemic to New Caledonia that grows in ultramafic (UF) and volcano-sedimentary (VS) soils.

Cell Death Mechanisms Induced by Photo-Oxidation Studied at the Cell Scale in the Yeast .

Blue light (400-430 nm) is known to induce lethal effects in some species of fungi by photo-oxidation caused by the excitation of porphyrins but the mechanisms involved remain poorly understood. In this work, we exposed the yeast to a high density light flux with two-photon excitation (830 nm equivalent to a one-photon excitation around 415 nm) and used quasi real-time visualization with confocal microscopy to study the initiation and dynamics of photo-oxidation in subcellular structures. Our results show that the oxidation generated by light treatments led to the permeabilization of the plasma membrane accompanied by the sudden expulsion of the cellular content, corresponding to cell death by necrosis.

Yeast quality in juvenile diet affects Drosophila melanogaster adult life traits.

Diet quality is critical for animal development and survival. Fungi can provide nutrients that are essential to organisms that are unable to synthetize them, such as ergosterol in Drosophila melanogaster. Drosophila studies examining the influence of yeast quality in the diet have generally either provided the diet over the whole life span (larva to adult) or during the adult stage and have rarely focussed on the juvenile diet.

The sensitivity of yeasts and yeasts-like fungi to copper and sulfur could explain lower yeast biodiversity in organic vineyards.

Although differences in yeast biodiversity have often been found between vineyards subjected to organic protection or conventional protection, little is known about the effect of copper and sulfur fungicides (the only fungicides allowed in organic farming) on yeast populations. The sensitivity to copper and sulfur of 158 yeast isolates of seven different species (Aureobasidium pullulans, Hanseniaspora guilliermondii, H. uvarum, Metschnikowia sp.

Wine microbiology is driven by vineyard and winery anthropogenic factors.

The effects of different anthropic activities (vineyard: phytosanitary protection; winery: pressing and sulfiting) on the fungal populations of grape berries were studied. The global diversity of fungal populations (moulds and yeasts) was performed by pyrosequencing. The anthropic activities studied modified fungal diversity.

Persistence of Two Non-Saccharomyces Yeasts (Hanseniaspora and Starmerella) in the Cellar.

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.

A Peptidoglycan-Remodeling Enzyme Is Critical for Bacteroid Differentiation in Bradyrhizobium spp. During Legume Symbiosis.

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.

FT-IR spectroscopy: A powerful tool for studying the inter- and intraspecific biodiversity of cultivable non-Saccharomyces yeasts isolated from grape must.

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 FT-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.

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.