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• W98053663 abstract "EnglishINFLUENCE OF WINE COMPONENTS OVER THE METABOLISM OF Oenococcus oeni AND OVER THE POPULATION DYNAMICS DURING MALOLACTIC FERMENTATION Malolactic fermentation (MLF) in wine is carried out by certain lactic bacteria which decarboxylate L-malic acid to L-lactic and CO2. Oenococcus oeni is the most tolerant species under the unfavourable wine conditions (nutrients starvation, low pH, ethanol, fatty acids from yeasts, SO2, etc.) and the main responsible of driving the MLF. As a consequence of the MLF, the wine quality improves because the acidity decreases, the organoleptic characteristics are better and the microbiological stability of wine increases. Some biochemical parameters, indicators of metabolic cellular conditions, are the ATPase activity and the expression of stress proteins and exoproteases involved in the obtention of nitrogen. On the other hand, some unfavourable conditions for bacterial growth can modify the bacterial population dynamics during MLF by effects over species and strains of the same species. The studies performed in this work show that ATPase-membrane activity principally corresponds to an H+-ATPase, which is affected by cellular viability inhibitory concentrations of ethanol, SO2, copper and fatty acids. So, a direct relationship between growth inhibition of O. oeni in real cellar conditions and ATPase activity inhibition is stablished. The stress protein profile produced by ethanol is not significantly different from the controls one, whereas the incubation in acidic conditions or in the presence of C12 fatty acid inhibits the protein expression in general. Copper and low pH induce the overexpression of a proteinic band close to 40 kDa, as SO2 does, which N-terminal sequence shows a significant identity with the family of glyceraldehyde-3-phosphate dehydrogenases (GAPDH). In his turn, SO2 inhibits the cytoplasmatic GAPDH activity also. Using RT-PCR, it has been shown that gene expression levels of hsp18 (the gene of a heat-shock protein found in O. oeni) as a response to the heat shock are near fifty-fold greater than in normal conditions. On the other hand, in contact with inhibitory concentrations of C12, copper or SO2, it only appears weak induction as a response to copper. About the exoprotease activity, this one is not significative in the strains studied, except for final exponential growth phase in the presence of high ethanol levels (14 %). Under conditions of nitrogen starvation, its observed a direct relationship between the bioavailability of a-amino nitrogen and growth rate of O. oeni. Different microvinification conditions were assayed using three different strains (CECT 4100 as the type strain; CR1, an strain isolated by our research group, and Vitilactic, a commercial strain). The type strain showed fewer ability for adaptation, whereas the isolated strain was the responsible for performing the FML the most times. To demonstrate that, we used Molecular Biology techniques, like specific PCR and RAPD-PCR. In cellar vinifications with normal and high levels of SO2 and lysozyme, it was observed a dominance of O. oeni species from the beginning of the alcoholic fermentation, and a different evolution of the populations in the presence of lysozyme. In all the cases, its the same strain which performs FML and it coincides with that one imposed in other campaigns and isolated by our group as CR1. catalaINFLUENCIA DE COMPONENTS DELS VINS SOBRE EL METABOLISME DOenococcus oeni I SOBRE LA SEVA DINAMICA DE POBLACIONS A LA FERMENTACIO MALOLACTICA La fermentacio malolactica (FML) del vi es el resultat del metabolisme dalgunes especies de bacteris lactics que converteix lacid L-(-)-malic en L-(+)-lactic i CO2. Lespecie Oenococcus oeni es la mes tolerant a les condicions poc favorables del vi (deficiencies nutritives, pH baix, etanol, acids grassos dels llevats, SO2, etc.) i la que habitualment realitza la FML. A part de la disminucio dacidesa, la FML contribueix a lestabilitzacio microbiologica del vi i a millorar-ne les qualitats organoleptiques. Alguns parametres bioquimics indicadors de lestat metabolic cel·lular son lactivitat ATPasa, lexpressio de proteines destres i dexoproteases involucrades en lobtencio de fonts de nitrogen. Daltra banda, algunes de les condicions desfavorables per al creixement bacteria poden influir sobre la dinamica de poblacions de bacteris lactics durant la FML, tant a nivell despecie com de soca. Els estudis realitzats en aquesta tesi indiquen que lactivitat ATPasa de membrana, deguda principalment a una H+-ATPasa, es veu afectada per concentracions inhibidores de la viabilitat cel·lular detanol, SO2, coure i acids grassos, per la qual cosa es pot establir una relacio directa entre la inhibicio del creixement dO. oeni en condicions reals de vinificacio i la inhibicio de lactivitat ATPasa. Al seu torn, letanol no produeix un perfil de proteines de membrana excessivament diferent respecte al control, mentre que la incubacio en condicions acides o en presencia de lacid gras C12 inhibeix, en general, lexpressio proteica. El coure i lacidesa afavoreixen la sobreexpressio duna proteina de membrana, de 40 kDa, aixi com el SO2, la sequencia N-terminal de la qual correspon a la familia de gliceraldehid-3-fosfatdeshidrogenases (GAPDH). El SO2 tambe inhibeix lactivitat GAPDH citoplasmatica, i per tant, el mecanisme glucolitic dobtencio denergia per part dO. oeni. Mitjancant RT-PCR, sha comprovat que els nivells dexpressio genica dhsp18 (gen duna proteina destres descrita en O. oeni) en resposta al xoc termic son fins a cinquanta vegades superiors que en les condicions controls, mentre que en presencia de concentracions de C12, coure o SO2 inhibidores del creixement, unicament sobserva una certa induccio en resposta al coure i en condicions de fase exponencial de creixement. Pel que fa a lactivitat exoproteasa, aquesta no es significativa en les condicions experimentals emprades i en les soques estudiades, excepte al final de la fase exponencial de creixement i en presencia de dosis elevades detanol (14 %). En condicions de carencia nutricional nitrogenada, sha observat una relacio directa entre la biodisponibilitat de nitrogen a-aminat i la taxa de creixement dO. oeni. Sassajaren diferents condicions de microvinificacio, amb tres soques diferents (CECT 4100, soca tipus; CR1, soca aillada pel nostre grup de recerca, i Vitilactic, soca comercial). La soca tipus va mostrar menor capacitat dadaptacio, mentre que la soca aillada simplanta en la majoria de casos. Per a comprovar-ho, sempraren tecniques de Biologia Molecular, com ara la PCR i la RAPD-PCR. En vinificacions amb concentracions moderades i elevades de SO2 i lisozim, sobserva un predomini de lespecie O. oeni ja des de linici de la fermentacio alcoholica, i una evolucio diferent de les poblacions en presencia de lisozim. En tots els casos, una mateixa soca simposa durant la FML, i coincideix amb la que shavia implantat en campanyes anteriors i aillada pel nostre grup com a CR1." @default.
• W98053663 created "2016-06-24" @default.
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• W98053663 date "2002-12-12" @default.
• W98053663 modified "2023-09-24" @default.
• W98053663 title "Influència de components de vins sobre el metabolisme d'Oenococcus oeni i sobre la seva dinàmica de poblacions a la fermentació malolàctica." @default.
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