Directed evolution of oenococcus oeni to improve acid-tolerance reveals fixed beneficial mutations in the citrate locus

Oenococcus oeni : advances in molecular genetics

International audience

Improving acid tolerance in Oenococcus oeni by Adaptive Evolution

International audience; Oenococcus oeni is a lactic acid bacterium (LAB) mainly responsible for the malolactic fermentation (MLF) inwine. MLF plays an important role in determining the final quality of wines[1]. Even though this LAB is naturally present in musts, wines and oenological environment, spontaneous MLF are usually unpredictable because of the stressful conditions and especially due to acidity [2]. The consequence of the mismanagement ofthis step might lead to the depreciation of wine quality. To obtain a clone more tolerant to acidity, we undertaken to replicate O. oeni in a temporally varying environment (pH 5.3 to 3.2) to improve acid tolerance. To discriminate stress tolerance…

Quantification des Brettanomyces par qPCR

International audience; Brettanomyces bruxellensis est une levure d’altération du vin avec de faibles besoins nutritionnels, résistante à l’éthanol et aux faibles pH, lui permettant une implantation en vin durant ou après la fermentation alcoolique (Conterno et al., 2006). B. bruxellensis est capable de produire des phénols volatils (éthyl-4-phénol, éthyl-4-gaïacol et éthyl-4-catéchol) (Oelofse et al., 2008). Ces molécules volatiles odorantes amènent un caractère phénolé et animal au vin connu sous le nom de « caractère Brett ». D’autres molécules (2-acétyltétrahydropyridine et 2-éthyltétrahydropyridine) produites par B. bruxellensis sont également responsables d’une déviation organoleptiqu…

Molecular mechanisms involved in the regulation of stress response in Oenococcus oeni and experimental evolution

Oenococcus oeni is the main bacterium responsible of malolactic fermentation in wine. This lactic acid bacteria grow in the stressful wine environment (high ethanol content, sulfites, low pH and low temperatures….). To maintain its cellular homeostasis, O. oeni has established mechanisms of resistance to its ecological niche. This research work focuses on the adaptative response of O. oeni to its environment and especially to acidity. Two approaches have been implemented (1) First, a targeted approach to characterize the molecular actors involved in regulating the general stress response. The RNA interference technique made possible the characterization of the repressor CtsR as well as two …

Adaptive evolution to improve acid tolerance in Oenococcus oeni

International audience; Oenococcus oeni is a lactic acid bacterium (LAB) mainly responsible for the malolactic fermentation (MLF) inwine. MLF plays an important role in determining the final quality of wines [1]. Even though this LAB is naturallypresent in musts, wines and oenological environment, spontaneous MLF are usually unpredictable because of thestressful conditions and especially due to acidity [2]. The consequence of the mismanagement of this step might leadto the depreciation of wine quality. To obtain a clone more tolerant to acidity, we undertook a replication of O. oeni until 450 generations in a temporally varying environment (pH 5.3 to 2.9) to improve acid tolerance. To discr…