Population dynamics and yeast diversity in early winemaking stages without sulfites revealed by three complementary approaches

Nowadays, the use of sulfur dioxide (SO2 ) during the winemaking process is a controversial societal issue. In order to reduce its use, various alternatives are emerging, in particular bioprotection by adding yeasts, with different impacts on yeast microbiota in early winemaking stages. In this study, quantitative-PCR and metabarcoding high-throughput sequencing (HTS) were combined with MALDI-TOF-MS to monitor yeast population dynamic and diversity in the early stages of red winemaking process without sulfites and with bioprotection by Torulaspora delbrueckii and Metschnikowia pulcherrima addition. By using standard procedures for yeast protein extraction and a laboratory-specific database of wine yeasts, identification at species level of 95% of the isolates was successfully achieved by MALDI-TOF-MS, thus confirming that it is a promising method for wine yeast identification. The different approaches confirmed the implantation and the niche occupation of bioprotection leading to the decrease of fungal communities (HTS) and Hanseniaspora uvarum cultivable population (MALDI-TOF MS). Yeast and fungi diversity was impacted by stage of maceration and, to a lesser extent, by bioprotection and SO2, resulting in a modification of the nature and abundance of the operational taxonomic units (OTUs) diversity

L’identification des levures et bactéries œnologiques par spectrométrie de masse de type MALDI-TOF

La spectrométrie de masse de type MALDI-TOF a été adaptée afin d’être utilisée comme outil innovant d’identification au niveau de l’espèce des levures et bactéries isolées d’échantillons variés (moûts, vins, boissons). L’analyse d’un grand nombre de clones permet d’apprécier la diversité des espèces de levures, bactéries acétiques et lactiques présentes dès les phases pré-fermentaires, au cours des fermentations, pendant l’élevage ou après conditionnement. Dans le cas d’altération de produits, cet outil innovant participera à une meilleure maitrise des risques microbiologiques

Motivation as a Mediator of the Relation Between Cognitive Reserve and Cognitive Performance

Objectives: Interindividual differences in cognitive aging may be explained by differences in cognitive reserve (CR) that are built up across the life span. A plausible but underresearched mechanism for these differences is that CR helps compensating cognitive decline by enhancing motivation to cope with challenging cognitive situations. Theories of motivation on cognition suggest that perceived capacity and intrinsic motivation may be key mediators in this respect. Method: In 506 older adults, we assessed CR proxies (education, occupation, leisure activities), motivation (perceived capacity, intrinsic motivation), and a global measure of cognitive functioning. Results: Perceived capacity, but not intrinsic motivation, significantly mediated the relation between CR and cognitive performance. Discussion: Complementary with neurobiological and cognitive processes, our results suggest a more comprehensive view of the role of motivational aspects built up across the life span in determining differences in cognitive performance in old age.This publication benefited from the support of the Swiss National Centre of Competence in Research LIVES–Overcoming Vulnerability: Life Course Perspectives, which is financed by the Swiss National Science Foundation (grant number: 51NF40-160590).Peer reviewe

An integrative approach to decipher the chemical antagonism between the competing endophytes paraconiothyrium variabile and Bacillus subtilis

An integrative approach combining traditional natural products chemistry, molecular networking, and mass spectrometry imaging has been undertaken to decipher the molecular dialogue between the fungus Paraconiothyrium variabile and the bacterium Bacillus subtilis, which were isolated as endophytes from the conifer Cephalotaxus harringtonia and are characterized by a strong and mutual antibiosis. From this study, we highlight that bacterial surfactins and a fungal tetronic acid are involved in such competition and that the fungus is able to hydrolyze surfactins to fight against the bacterial partner

Le rapport au corps des joueurs de rugby fauteuil

Objectif : La relative brutalité du rugby fauteuil contraste avec la fragilité qui pourrait être perçue chez des personnes en situation de handicap. Le corps, soumis à des limitations fonctionnelles au quotidien, se trouve en action. Le but de ce travail est alors d’explorer ce que modifie le rugby fauteuil sur le rapport au corps des joueurs.Méthodes : Cette étude exploratoire est basée sur des observations structurées, des entretiens semi-directifs, et l’autoquestionnaire de l’inventaire du soi physique. La population d’étude est composée de joueurs de rugby fauteuil de tout niveau. Une analyse thématique, croisée avec les autres données, est présentée.Résultats : Cinq joueurs défenseurs ont été volontaires. La sensation d’avoir acquis de la force, la représentation d’un corps puissant et la mise en mouvement propre au rugby fauteuil semblent influencer positivement le rapport au corps des joueurs interrogés. Ce bénéfice serait constaté dans la pratique sportive et dans le quotidien. La manière dont ces cinq joueurs investissent leur corps, notamment dans le soin préventif, paraît être influencée par cette pratique. L’estime de soi dans le domaine corporel semble positive, notamment par l’acquisition de nouvelles compétences. Cette étude décrit les bénéfices du rugby fauteuil sur le rapport au corps qui s’avère être influencé par plusieurs facteurs

Laminariales Host Does Impact Lipid Temperature Trajectories of the Fungal Endophyte Paradendryphiella salina (Sutherland.)

International audienceKelps are colonized by a wide range of microbial symbionts. Among them, endophytic fungi remain poorly studied, but recent studies evidenced yet their high diversity and their central role in algal defense against various pathogens. Thus, studying the metabolic expressions of kelp endophytes under different conditions is important to have a better understanding of their impacts on host performance. In this context, fatty acid composition is essential to a given algae fitness and of interest to food web studies either to measure its nutritional quality or to infer about its contribution to consumers diets. In the present study, Paradendryphiella salina, a fungal endophyte was isolated from Saccharina latissima (L.) and Laminaria digitata (Hudson.) and its fatty acid composition was assessed at increasing salinity and temperature conditions. Results showed that fungal composition in terms of fatty acids displayed algal-dependent trajectories in response to temperature increase. This highlights that C18 unsaturated fatty acids are key components in the host-dependant acclimation of P. salina to salinity and temperature changes

The presence of shade-intolerant conifers facilitates the regeneration of Quercus petraea in mixed stands

International audiencePositive productivity-diversity relationships, pest-effect mitigation and increased resilience and stability maintain an ongoing interest for mixed stands in forestry. However, how mixing species affects forest regeneration is yet to be further explored.We used data from the French National Forest Inventory (from 2006 to 2016) to model Quercus petraea (Matt.) Liebl regeneration cover in pure and mixed Quercus petraea stands; we included the effects of abiotic and biotic factors as well as mixture. We hypothesized that the characteristics of the companion species would prevent or facilitate the regeneration of oak.Quercus petraea regeneration cover in this study responded negatively to total canopy cover and herbivory pressure. Mean July potential evapotranspiration (PET), mean December maximal temperature and soil pH are variables whose spatial variations over a given territory structure regeneration cover; all three of these variables have optimum values. Quercus petraea regeneration cover is linked to the proportion of Quercus petraea in the canopy layer in all mixed stands, except when the oak is mixed with shade-intolerant conifers: in this case, Quercus petraea regeneration is enhanced. The shade tolerance of admixed broadleaved species did not affect the Quercus petraea regeneration. This suggests that oak regeneration was facilitated with a shade-intolerant coniferous companion species due to better light transmittance through the crown or the competitive advantage of Quercus petraea over coniferous shade-intolerant species.These results are of interest for oak mixtures since Quercus petraea regeneration cover benefits from mixtures with shade-intolerant conifers and is at least equal to that of pure stands

Live single-cell metabolomics with matrix-free laser/desorption ionization mass spectrometry to address microalgal physiology

Single cell heterogeneity of unicellular organisms within a population is generated by external cues or random genetic mutations. This causes a non-uniform phenotype within populations, with the potential to impact the response of the entire ecosystem. Here, we propose an effective, rapid and versatile method to analyze single cells associated to aqueous substrate with laser-desorption/ionization mass spectrometry (LDI-MS) using a simple and inexpensive matrix-free support. The cells deposited on a cultivation-medium wetted support are analyzed with minimal disturbance as they remain in their natural viable state until their disruption during LDI-MS. Metabolites desorbed from single cells are analyzed on High-Resolution Mass Spectrometry (HRMS) using the Orbitrap FT-MS technology to broadly fingerprint cellular chemistry. This single-cell mass spectrometry (SC-MS) allows assessing the physiological status and strain-specificity of different microalgae, including diatoms and chlorophytes, at the single-cell level. We further report a reliable and robust data treatment pipeline by performing multivariate statistics on the repeated SC-MS measurements. Comparing single cell MS spectra from natural phytoplankton samples and from laboratory strains allows the identification and discrimination of inter and intra-specific metabolic variability and thereby has promising applications in determining the taxonomic composition of highly complex phytoplankton blooms. Notably, the herein described matrix-free live-single-cell LDI-HRMS approach enable monitoring dynamics of the plankton and explain why key-players cells survive, thrive, avoid selective feeding or pathogenic virus and bacteria, while others are overcome and die

Older adults’ beliefs about forgetting and aging predict memory self-efficacy above and beyond actual memory performance and mental health

International audienc

Bacterial–Fungal Interactions in the Kelp Endomicrobiota Drive Autoinducer-2 Quorum Sensing

International audienceBrown macroalgae are an essential component of temperate coastal ecosystems and a growing economic sector. They harbor diverse microbial communities that regulate algal development and health. This algal holobiont is dynamic and achieves equilibrium via a complex network of microbial and host interactions. We now report that bacterial and fungal endophytes associated with four brown algae (Ascophyllum nodosum, Pelvetia canaliculata, Laminaria digitata, and Saccharina latissima) produce metabolites that interfere with bacterial autoinducer-2 quorum sensing, a signaling system implicated in virulence and host colonization. Additionally, we performed co-culture experiments combined to a metabolomic approach and demonstrated that microbial interactions influence production of metabolites, including metabolites involved in quorum sensing. Collectively, the data highlight autoinducer-2 quorum sensing as a key metabolite in the complex network of interactions within the algal holobiont