Biogenic amine in wines

International audience; Biogenic amines (BA) are a group of organic nitrogenous compounds formed and degraded by the metabolism of living organisms (microorganisms, plants and animals). The main BA associated with wine are putrescine, histamine, tyramine and cadaverine, followed by phenylethylamine, spermidine, spermine, agmatine and tryptamine. The variability in the BA content of wine could be explained on the basis of differences in the winemaking process, time and storage conditions, raw material quality, and possible microbial contamination during winery operations. BA are formed by decarboxylation of the corresponding amino acids by microorganisms through substrate-specific decarboxylase enzymes. This property is usually strain dependent. Decarboxylase enzymes are generally induced at acidic pH and therefore they have a possible role in maintaining pH homeostasis or extending the microbial growth period by detoxification of the extracellular medium. The presence of these compounds is considered by some authors a fundamental parameter for the detriment of wine

Estimation des densités et tailles de population du Microcèbe Roux du Nord de (Microcebus tavaratra) dans la région Loky-Manambato (Daraina)

La région Loky-Manambato dans le Nord de Madagascar, est connue pour abriter le propithèque à couronne dorée (Propithecus tattersalli), un lémurien emblématique et endémique de la région. Néanmoins cette région composée d’une dizaine de fragments forestiers de taille moyenne et encore relativement peu étudiés, abrite aussi le microcèbe roux du nord (Microcebus tavaratra). Malgré la gestion des forêts de cette région par l’ONG Fanamby depuis 2005, aucune étude n’avait encore été menée dans chacun des fragments forestiers de la région pour déterminer la présence et quantifier la taille des populations de microcèbes de chacun d’entre eux. Lors de notre étude nous avons tenté d’estimer les densités et les tailles des populations de M. tavaratra dans neuf des dix principaux fragments forestiers de la région. Dans ce but nous avons utilisé la méthode de «line transect distance-sampling». Nos résultats montrent que les densités de microcèbes sont relativement élevées, et varient de 28 à 325 ind/km² entre fragments forestiers de la région. Desétudes plus approfondies des données collectées seront nécessaires pour déterminer les variables environnementales responsables des différences de densité observées.FCT grant: (SFRH/BD/64875/2009); l’Institut Français de la Biodiversité, GDRI Madagascar, “Laboratoire d’Excellence” (LABEX) TULIP: (ANR -10-LABX-41)

Daraina sportive lemur (Lepilemur milanoii) density and population size estimates in most of its distribution range: the Loky-Manambato region.

The population of the Daraina sportive lemur (Lepilemur milanoii) is believed to be mostly confined to the Loky-Manambato region (Louis et al., 2006). Very little is known about L. milanoii and it is classified as “Data Deficient” by the IUCN (IUCN, 2013; Schwitzer et al., 2013). Despite the management of the area by the NGO Fanamby since 2005, no study had been conducted to determine the presence and the abundance of L. milanoii in the main forest fragments of the region. During the 2011 dry season we surveyed the ten main forest fragments of the Loky-Manambato region and estimated L. milanoii densities and population sizes using line transect distance sampling (Buckland, 2001) and the DISTANCE software (Thomas et al., 2010). The results suggest that sportive lemur densities are reasonably high in the region, but with important discrepancies between forest fragments, with densities ranging from 49.8 ind./km² in Antsaharaingy to 590.5 ind./km² in Ampondrabe. For the region Loky-Manambato we were able to estimate a population size of 52,000 individuals. This is the first estimate for the total population size and we argue that similar studies should be repeated to monitor environmental changes and anthropogenic pressures (hunting, deforestation, mining, etc.).FCT grant: (SFRH/BD/64875/2009); the Groupement de Recherche International (GDRI); "Laboratoire d’Excellence" (LABEX) entitled TULIP : (ANR-10-LABX-41); Rufford Small Grant Foundation grant: (10941-1)

Glycerol export and glycerol-3-phosphate dehydrogenase, but not glycerol phosphatase, are rate limiting for glycerol production in Saccharomyces cerevisiae

43 ref.International audienc

Glycerol formation during wine fermentation is mainly linked to Gpd1p and is only partially controlled by the HOG pathway

36 ref.International audienc

Les parois cellulaires et la maturation de la baie de raisin : activités enzymatiques participant à leur évolution

National audienc

Design and performance testing of a real-time PCR assay for sensitive and reliable direct quantification of Brettanomyces in wine

International audienceBecause the yeast Brettanomyces produces volatile phenols and acetic acid, it is responsible for wine spoilage. The uncontrolled accumulation of these molecules in wine leads to sensorial defects that compromise wine quality, The need for a rapid, specific, sensitive and reliable method to detect this spoilage yeast has increased over the last decade. All these requirements are met by real-time PCR. We here propose improvements of existing methods to enhance the robustness of the assay. Six different protocols to isolate DNA from a wine and three PCR mix compositions were tested, and the best method was selected. Insoluble PVPP addition during DNA extraction by a classical phenol:chloroform protocol succeeded in the relief of PCR inhibitors from wine. We developed an internal control which was efficient to avoid false negative results due to decreases in the efficiency of DNA isolation and/or amplification. The method was evaluated by an intra-laboratory study for its specificity, linearity, repeatability and reproducibility. A standard curve was established from 14 different wines artificially inoculated. The quantification limit was 31 cfu/mL (C) 2008 Elsevier B.V. All rights reserved

Analyse de la composition en glucides de la paroi cellulaire, et de l'activité de la beta-galactosidase en relation avec un clone de cADN pendant le developpement de la baie de raisin, Vitis vinifera)

International audienc

Co-inoculation of selected Saccharomyces cereviseae and Oenococcus oeni starter cultures may reduce biogenic amines content in regional wines.

Many microorganisms are used as starter cultures in several fermented foods and beverages. In general, the choice of starter cultures is fundamental in order to guarantee the quality of final products. For this reason, the inability to form Biogenic Amine (BA) should be an important criteria in the selection of starter cultures for the management of fermented food and beverages. Inoculation with starter cultures that are unable to produce biogenic amines is a viable option for the control of these compounds in wine (Spano et al., 2010). Malolactic fermentation (MLF) of wine generally starts spontaneously when the population of indigenous Lactic Acid Bacteria (LAB) reaches a sufficient level. When the conditions of wine are favourable to the development of BA-producing LAB, spontaneous MLF can lead to the accumulation of significant amounts of BA (Lonvaud-Funel, 2001). In contrast, when MLF is performed under controlled conditions after inoculating the wine with a selected strain of Oenococcus oeni unable to form BA, the amounts of BA are markedly reduced (Martin-Alvarez et al. 2006). It seems that co-inoculation of Saccharomyces cereviseae and Oenococcus oeni starter cultures has the potential to curb BA formation even more than conventional inoculation for malolactic fermentation after the completion of alcoholic fermentation. The present work present the application of realible Saccharomyces cereviseae/Oenococcus oeni association starter cultures in order to reduce BA content (mainly putrescine) in regional wine

Enzymic activities and cell walls during grape berry ripening: pectin methyl-esterase and transcript expression

International audienc