ISSN: 2471-9315
Marguerite Dols-Lafargue
Several wine lactic acid bacteria, especially Pediococcus parvulus and Oenococcus oeni, have been described exopolysaccharides producers. O. oeni is the bacterium that most frequently performs malolactic fermentation in temperate areas, while P. parvulus is rather considered a spoilage agent, because many strains cause wine ropiness. This alteration is linked to the accumulation of β-glucan in the wine. The polymer synthesis is catalyzed by a glucosyltransferase Gtf, encoded by the gtf gene. A detailed study has shown that this gene was much more common than could have been expected from the ropy phenotype prevalence among wine lactic acid bacteria. In addition, many other genetic determinants associated with the production of exopolysaccharides have been identified and associated with more "discrete" phenotypes, especially in O. oeni. Instead being detrimental to wine quality, these polymers may be valued in several ways in the future, as their presence is clearly correlated with better survival of bacteria in several situations. This could allow the development of more robust malolactic starters.