Comparative genomics in the wine bacterium Oenococcus oeni

The production of wine from grape juice relies on the combined actions of both yeast and bacteria which shape the aroma and flavour of wine through the production of secondary metabolites and the biochemical transformation of many grape-derived constituents. Whereas the principal wine yeast, Saccharomyces cerevisiae, is primarily involved in the alcoholic fermentation in which glucose and fructose are converted into alcohol, the wine bacterium, Oenococcus oeni, is primarily involved in a secondary fermentation reaction where malic acid is decarboxlyated into lactic acid. This conversion, known as malolactic fermentation (MLF), results in an increase in wine pH and reduction in the sourness of the wine, while also providing microbial stability through the reduction of potential carbon sources for wine spoilage bacteria such as Lactobacilli and Pediococci1. In addition to its primary role in performing MLF, the metabolic by-products produced during the growth of O. oeni in wine have been shown to positively contribute to the flavour and mouth feel of wines which have undergone MLF.