Effect of glutathione addition on Oenococcus oeni tolerance to stressful wine-like conditions.

LUCÍA M. MENDOZA; ISABEL ARAQUE; RAÚL R. RAYA; ALBERT BONDONS; CRISTINA REGUANT

Mar del PLata

Congreso; 51th Annual Meeting Argentine Society for Biochemistry and Molecular Biology.; 2015

SAIB

During wine-making process, the malolactic fermentation (MLF) is a critical step to obtain high quality wines being Oenococcus oeni the most important species involved in this fermentation. O. oeni viability in wine depends on its resistance to several stress factors such as low pH, ethanol and other inhibitory metabolites produced by yeasts. Glutathione is a nonproteic tripeptide that in its reduced form acts as an antioxidant through the thiol group of cysteine. The aim of this work was to evaluate if glutathioneaddition could increase tolerance of O. oeni to stressful conditions. O. oeni X2L was cultured in MRS medium with and without glutathione (5 mM). The strain showed better growth parameters in presence of glutathione. This positive effect was more remarkable when the bacterium grew at low pH (4 and 3.4) and/or in presence of ethanol. Moreover, expression of gsh gene encoding glutathione reductase increased 3-fold by glutathione addition at different culture conditions while expression levels of cfa gene encoding cyclopropane fatty acid synthase increased 2-fold only in presence of glutathione and ethanol. Also, glutathione addition produced modifications in the fatty acid composition of bacterial membrane. These results showed the potential protective role of glutathione on O. oeni which could improve its stress response as well as MLFperformance during wine elaboration.