Selecting LAB for Use as Starter Cultures in Winemaking

The use of selected bacteria by the wine industry began in the 1990s and is booming in recent years. Selected LAB help to better control malolactic fermentation kinetics, they limit wine spoilages due to undesirable microorganisms and they ensure wine safety by avoiding the production of harmful biogenic amines that may occur during spontaneous fermentations carried out by indigenous bacteria. At the same time, the development of organic, biodynamic and traditional farming is raising questions about the possible loss of identity of wines produced with selected bacteria. One may wonder whether the selection of bacteria used as malolactic starters -which is now based solely on their technological properties and safety (e.g., no biogenic amine formation) – must also consider their geographical origin, in order to propose starters that match each type of wine. Oenococcus oeni is by far the main LAB species that develops naturally in wine and achieves malolactic fermentation. Accordingly, almost all the malolactic starters commercialized today are strains of this species. Numerous studies using diverse molecular techniques have shown that there is a wide variety of O. oeni strains in different regions and wines. Today, comparative genomics brings a new light on the diversity of this species, the geographic spread of strains and their adaptation to wine. Although all strains may spread in all regions, it is clear that certain "genetic families" of strains have appeared separately in different regions, representing a genetic adaptation to different types of wines. This presentation will discuss these results and their impact on the selection of malolactic starters.