PROTEOMIC RESPONSES OF Oenococcus oeni TO STRESSFUL WINE-LIKE CONDITIONS

LUCÍA M. MENDOZA, SILVINA FADDA, MIGUEL FERNÁNDEZ DE ULLIVARRI, RAÚL RAYA

San M de Tucumán, Tucumán, Argentina.

Simposio; IV Simposio Internacional de Bacterias Lácticas.; 2013

CERELA

Oenococcus oeni is the most important species involved in the convertion of malic acid into lactic acid and carbon dioxide (malolactic fermentation; MLF) at the end of the alcoholic fermentation (AF) during the wine-making process, being the MLF a critical step to obtain a high quality final product. 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 get a deeper insight in the molecular factors involved in the adaption of O. oeni to these harmful conditions, physiological and biochemical studies were carried out with the O. oeni strain X2L during its growth in a y east fermented medium (YFM). O. oeni X2L reached less biomass in YFM than when it was grown in the unfermented medium, even though the MLF was complete in both media. To investigate the mechanisms that helps O. oeni X2L to tolerate and survive these harmful conditions, a proteomic approach was performed using two-dimensional electrophoresis. A total of 357 cytoplasmic proteins were detected when O. oeni grew in fresh (control) and YFM broth media. Thirty two protein spots showed significant changes in expression during growth in YFM: 14 were up-regulated while 16 proteins down-regulated. One spot (aminotransferase/fructokinase) was specific to YFM while another spot (aspartate carbamoyltransferase) was completely inhibited in this condition. Fifteen proteins showing the most significant variation were then identified by MALDI TOF-MS analysis. In YFM, enzymes involved in carbohydrate, lipid and amino acids metabolism, as well as chaperone proteins were overexpressed, while enzymes related to lipid biosynthesis, glycolysis, amino acid metabolism, hydrolases and dehydrogenases were down regulated. These results indicate that multiple metabolic pathways are involved in the response of O. oeni X2L to stressful conditions related to wine fermentation. This study contributes to identify the metabolic pathways involved in stress tolerance of O. oeni, which would allow choosing the best adapted bacterial strains to complete successfully the MLF during wine fermentation conducted by Saccharomyces cerevisiae .