Oenococcus oeni: Queen of the cellar, nightmare of geneticists.

Oenococcus oeni is a wine-associated lactic acid bacterium (LAB) responsible mostly for wine malolactic fermentation (MLF). This fastidious bacterium (auxotrophic for many amino acids and slow growing) possesses remarkable adaptability to harsh physicochemical conditions and can reprogramme its metabolic pathways to enhance its survival in wine. Thus, O. oeni is an instructive bacterial model for investigating stress response mechanisms in LAB. However, the lack of appropriate techniques to modify the O. oeni genome has hampered molecular studies of this species. The application of recent advances in molecular genetics promises to provide a better understanding of the regulation of stress responses in this species in the future.