Molecular basis of Oenococcus oeni stress response to inhibitory compounds produced by wine yeasts during fermentation

MENDOZA, L; FADDA S; G. VIGNOLO; RAYA, R

Simposio; 11 LAB SYMPOSIUM; 2014

Molecular basis of Oenococcus oeni stress response to inhibitory compounds produced by wine yeasts during fermentation Lucía M. Mendoza, Silvina Fadda, Graciela Vignolo, Raúl Raya Centro de Referencia para Lactobacilos (CERELA), CONICET, Tucumán, Argentina   Oenococcus oeni is the most important lactic acid bacterium species involved in the induction of malolactic fermentation (MLF) at the end of the alcoholic fermentation (AF) during wine-making process. MLF is a critical step to obtain a high quality final product. However, bacterial growth and MLF are not always successful due to the harsh environmental conditions of wine. The viability of O. oeni in wine depends on its resistance to several stress factors such as acidity, SO2, ethanol and other inhibitory metabolites produced by wine yeasts. To study the possible mechanisms that O. oeni X2L utilizes to survive and carry out the MLF in stressful wine conditions, a proteomic approach (2D-E) and RT-PCR were performed. O. oeni X2L was grown in unfermented (control) and fermented grape juice. Forty three proteins spots showed significant changes in expression during growth in fermented juice: 23 spots were up-regulated while 18 proteins down-regulated. One spot (aminotransferase/fructokinase) was specific to fermented medium while another spot (aspartate carbamoyltransferase) was completely inhibited in this condition. Enzymes involved in carbohydrate, lipid, nucleotide and amino acids metabolism, as well as chaperone proteins (DnaK/DnaJ) and two peptidases (oligopeptidase F and endopeptidase O) were over-expressed while enzymes related to lipid biosynthesis, glycolysis, amino acid metabolism, hydrolases and dehydrogenases were down-regulated. Also, differential expression of genes involved in malic acid and citrate metabolism was observed when O. oeni grew in fermented medium. This study contributes to the knowledge of the molecular mechanisms used by O. oeni to tolerate stressful wine conditions as well as to the selection of the best adapted starter culture to carry out successfully the MLF during wine-making.