EFFECT OF AN INHIBITORY PEPTIDIC FRACTION PRODUCED BY WINE YEASTS ON THE PROTEOME OF Oenococcus oeni

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

San Miguel de Tucumán

Simposio; IV Simposio Internacional de Bacterias Lácticas (SIBAL) Alimentos, Salud y Aplicaciones; 2013

Centro de Referencia para Lactobacilos

Oenococcus oeni is the best adapted wine lactic acid bacteria and is almost exclusively used for the induction of malolactic fermentation (MLF) which consists in the convertion of malic acid into lactic acid 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. In fact, some inhibitory metabolites produced by yeasts during AF such as ethanol, SO2 and peptides influence on O. oeni behavior. In a previous study we found that O. oeni X2L reached less biomass in fermented medium as well as in presence of a peptidic fraction produced by yeast (PF) than when it grew in the unfermented medium (control), even though the MLF was completely achieved in all tested conditions. To evaluate the possible mechanisms that O. oeni X2L utilizes to survive and carry out the MLF in presence of PF, a proteomic approach was performed using 2D electrophoresis. O. oeni X2L was grown in grape juice medium with and without addition of PF. A total of 357 cytoplasmic proteins were detected independently of growth conditions. Eleven protein spots showed differential expression with a factor greater than 1.5 during bacterial growth in presence of PF. Chaperone GroEL and elongation factor Tu were the only proteins that decreased the expression when O. oeni was exposed to PF. Among proteins up-regulated, two peptidases (oligopeptidase F and endopeptidase O), acetolactate kinase and trascription terminator NusA showed the highest expression change. Other proteins overexpressed with variable intensities were ATP-binding subunit of Clp protease, DnaK/DnaJ chaperones and proteins related to nucleotide and carbohydrate metabolism such as ribonuclease III, dihydroxyacetone kinase, preprotein translocase and ribonucleotide diphosphate reductase. The over-expression of general stress proteins and enzymes involved in carbohydrate metabolism and nucleotide synthesis permits the growth and enzymatic activity of O. oeni in presence of inhibitory PF. The results obtained in this work contribute to the understanding of the molecular mechanisms used by O. oeni to tolerate wine conditions, particularly its response to the presence of inhibitory peptides produced by Saccharomyces cerevisiae during AF. The knowledge of O. oeni response to stress will allow the future selection of the best adapted strain as starter culture to carry out successfully the MLF during wine-making.