Impact of the surface properties of lactic bacteria on the stability of emulsions

Bacteria have physicochemical surface properties which depend on the chemical composition of the cell surface. These characters proceed from several type of physicochemical interactions and are involved in attachment processes of microorganisms to surfaces. Thus they are of interest in several areas, as biomedicine, formation of biofilms and adhesion to apolar surfaces. Moreover, food matrix are complex heterogeneous media, which structure settles on interaction forces between molecules (van der Waals, electrostatic or structural forces…). When bacteria are present in a matrix, it is probable that their surface interacts with the other constituents. So far, few studies have mentioned this subject. In order to understand the involvement of cells surface properties in a food matrix, the effect of surface properties of lactic bacteria on the stability of model emulsions were studied. The results showed that the choice of a bacterium according to its surface properties may have a strong impact on the stability and on the behavior of an emulsion

The Use of Enzymes and Microorganisms for the Production of Aroma Compounds from Lipids

Lipids are an important source of aroma compounds. In foods, lipids are degraded or modified by enzymatic activities that are originally present in the raw materials or that develop later due to the growth of microorganisms. Mimicking these natural pathways, some processes have been developed to produce aroma compounds in bioreactors. In this review we describe the production of aroma compounds from different families: lactones, green notes and ionones. We focus on points that are specific to these reactions in heterogeneous media: physicochemical forces involved in the interactions between the substrate, product and biocatalyst, transfers between the phases and, as the degradation of lipids often requires an oxidation step, on the problems of oxygenation of the reactors

Nigrostriatal Dopaminergic Denervation Does Not Promote Impulsive Choice in the Rat: Implication for Impulse Control Disorders in Parkinson’s Disease

Impulse control disorders (ICDs) are frequent behavioral complications of dopaminergic (DA) replacement therapies (DRTs) in Parkinson’s disease (PD). Impulsive choice, which refers to an inability to tolerate delays to reinforcement, has been identified as a core pathophysiological process of ICDs. Although impulsive choices are exacerbated in PD patients with ICDs under DRTs, some clinical and preclinical studies suggest that the DA denervation of the dorsal striatum induced by the neurodegenerative process as well as a pre-existing high impulsivity trait, may both contribute to the emergence of ICDs in PD. We therefore investigated in a preclinical model in rats, specifically designed to study PD-related non-motor symptoms, the effect of nigrostriatal DA denervation on impulsive choice, in relation to pre-existing levels of impulsivity, measured in a Delay Discounting Task (DDT). In this procedure, rats had the choice between responding for a small sucrose reinforcer delivered immediately, or a larger sucrose reinforcer, delivered after a 0, 5, 10 or 15 s delay. In two different versions of the task, the preference for the large reinforcer decreased as the delay increased. However, and in contrast to our initial hypothesis, this discounting effect was neither exacerbated by, or related to, the extent of the substantia nigra pars compacta (SNc) DA lesion, nor it was influenced by pre-existing variability in impulsive choice. These results therefore question the potential implication of the nigrostriatal DA system in impulsive choice, as well as the DA neurodegenerative process as a factor contributing significantly to the development of ICDs in PD

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Les acyl-Coenzyme A oxydases de Yarrowia lipolytica, rôle dans la production d'arômes

DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Archivage électronique et analyse de risque : les nouveaux défis de l’archiviste

L’ère du numérique a causé de profondes transformations à la discipline archivistique. De nouveaux enjeux font ainsi surface. C’est notamment le cas de la notion de risque, qui doit invariablement être prise en compte lors de la définition des besoins dans un organisme.Dans leur article, Belin et Rietsch font d’abord référence à l’évolution du numérique. Depuis quinze ans, l’arrivée du numérique apporte, certes, beaucoup d’avantages au travail des archivistes, mais aussi tout un lot de nouvelles problématiques. En effet, réussir à assurer l’intégrité d’un document numérique, sa provenance, sa confidentialité, son accès ou sa préservation à long terme, sont tous des défis qui nous rappellent que cette nouvelle ère est parfois fondée sur des mécanismes de fonctionnement complexes et exigeant des coûts monétaires importants.La seconde partie de l’article est dédiée à la présentation d’un cas concret : le succès de la mise en place d’un système d’archivage électronique (SAE) régional mutualisé au sein du syndicat mixte de coopération territoriale Mégalis Bretagne, en France. Le succès de cette opération repose principalement sur l’aspect de mutualisation des moyens, c’est-à-dire la mise commun d’un système détenant plusieurs infrastructures techniques. Ce type de système permet d’assurer l’optimisation des ressources disponibles et les risques sont ainsi partagés. Une politique d’archivage bien réfléchie est absolument nécessaire avant la mise en place d’un tel système. L’exemple du système de Mégalis Bretagne illustre bien l’association d’un projet d’archivage numérique et l’analyse du risque.The digital era has caused tremendous transformation in the discipline of archival science. New issues are surfacing. This is particularly true with respect to the notion of risk, which has to be taken into account in defining the needs of an organization.In this article, Belin and Rietsch discuss the evolution of the digital in archives. Over the past fifteen years, the arrival of digital has certainly brought many advantages to the work of archivists, but it has also introduced a cluster of new problem areas. In fact, success in assuring the integrity of a digital document, its provenance, its confidentiality, and its long-term accessibility are all challenges that make us recall that the new era is sometimes based on complex functional mechanisms with significant costs.The second part of the article is dedicated to the presentation of an actual case : the successful installation of a shared regional electronic archiving system for the mixed territorial cooperative union Mégalis Bretagne, in France. The success of the operation is primarily due to the sharing of means, that is, the shared use of a system that has several technical infrastructures. This kind of system means that one can assure the optimization of available resources and the sharing of risks. An archival policy that is well thought out is absolutely necessary before putting such a system in place. The example of the Mégalis Bretagne system serves as a good illustration of a digital archival project and an analysis of risk

Biotransformation de lipides en arômes par Yarrowia lipolytica (interactions avec le substrat, excrétion et toxicité des métabolites produits)

Yarrowia lipolytica produit, par biotransformation, de la g-décalactone, composé d'arôme issu de la dégradation peroxysomale du ricinoléate de méthyle. Certaines étapes potentiellement limitantes ont été étudiées. L'assimilation du substrat émulsionné se fait par adhésion de microgouttelettes sur la surface cellulaire (via des interactions hydrophobes et de type acide/base de Lewis) et par action d'un surfactant. Le substrat n'est pas accumulé, ce qui rend non limitant sa dégradation intracellulaire en acide 4-hydroxy-décanoïque, précurseur direct de la g-décalactone. Ces deux composés peuvent être libérés par Y. lipolytica, le premier via un transporteur membranaire, comme le suggère nos résultats, le second semblant franchir les membranes passivement. La lactone interagit avec un phospholipide modèle, entraîne in vivo une forte augmentation de la fluidité des membranes puis une chute du potentiel membranaire: ces mécanismes sont à la base de la toxicité de la lactone pour la levure.Yarrowia lipolytica produces, through biotransforamtion, g-decalactone, an aroma compound stemming from the peroxisomal degradation of methyl ricinoleate. Some steps potentially limiting were studied. The assimilation of the emulsified substrate is medited by the adhesion of microdroplets on the cell surface (via hydrophobic or Lewis acid/base interactions) and by the action of a surfactant. The substrate is not accumulated by the yeast, making non-limiting its intracellular degradation into 4-hydroxydecanoic acid, the direct precursor of g-decalactone. These two compounds can be released by Y. lipolytica, the first one via a membrane transporter, as suggested by our results, the second one seems to cross passively the membranes. The lactone interacts with a model phospholipid, it leads in vivo to a strong increase in membrane fluidity and then to a drop in membrane potential: these mechanisms bring about lactone toxicity in yeast.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Aspects de la dégradation de substances hydrophobes en composés d arômes par la levure Yarrowia lipolytica

La levure Yarrowia lipolytica est un organisme modèle pour la dégradation de lipides et/ou d autres composés hydrophobes. Elle est en particulier utilisée pour transformer ces substrats en composés d'arômes mais la mauvaise maîtrise du catabolisme des lipides, notamment des flux de beta-oxydation, entraîne un rendement limité de la production des composés d arômes. Dans cette étude, la biotransformation du ricinoléate de méthyle en décalactones a été choisie comme voie modèle car quatre lactones peuvent s'accumuler correspondant à différents niveaux de sortie du cycle de beta-oxydation. Des variations des conditions environnementales ont été réalisées afin d'étudier leur impact sur la production des quatre lactones. Les variations d'aération du milieu ont eu un gros impact sur l'accumulation de la gamma-décalactone produite à faible aération (496 mg/L) et la 3-hydroxy-gamma-décalactone, précurseur des déc-2 et 3-én-4-olides, dont la production dépendait de l'oxygène dissous mais aussi du pH (1,074 g/L). Ceci confirme que l accumulation des lactones est liée à des étapes catalytiques exigeant de l oxygène. L accumulation de cette dernière lactone suggère une grande importance de la régénération du NAD+ peroxysomal pour favoriser l activité de la 3-hydroxyacyl-CoA déshydrogénase. A côté de l'effet de l'aération sur les productions de lactone, il a été mis en évidence un effet de ce paramètre sur l adhésion des cellules au matériau du bioréacteur, ce qui entraîne une modification des flux. De plus, des métabolites ont été ajoutés pour modifier les flux de beta-oxydation et l accumulation de gamma-décalactone ou de 3-hydroxy-gamma-décalactone.The yeast Yarrowia lipolytica is a model organism for the degradation of lipids and/or other hydrophobic compounds. It is used to transform these substrates into aroma compounds but the low control of the catabolism of lipids, in particular of beta-oxidation fluxes results in limited rate of production. In the present study, the biotransformation of methyl ricinoleate into decalactones has been chosen as a model pathway as it can give rise to four lactones corresponding to different levels of exit from the beta-oxidation cycle. Variations of the environmental conditions were carried out to detect their impact on the production of the four lactones. The variations of aeration had a significant impact on the accumulation with gamma-decalactone accumulating more in low aeration conditions (496 mg/L) and the accumulation of 3-hydroxy- gamma-decalactone, precursor of the dec-2 and 3-en-4-olides, depended on aeration but also on pH and reached 1.074 g/L. This confirms that the accumulation of lactones is related to oxygen-requiring catabolic steps. The accumulation of the latter lactone suggests a regeneration of the NAD-oxidation fluxes as well as the accumulation of gamma-decalactone or 3-hydroxy-gamma-decalactone.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF