Evaluation of exopolysaccharide production by Leuconostoc mesenteroides strains isolated from wine.

Exopolysaccharide (EPS)-producing lactic acid bacteria are responsible for the alteration of wine and other fermented beverages. The potential to produce EPS was investigated for Leuconostoc mesenteroides strains isolated from Spanish grape must and wine. Most strains were able to produce EPS from sucrose containing media. Based on their EPS-producing phenotype and on their EPS monosaccharide composition, the L. mesenteroides strains analyzed could be arranged in 2 groups. One group comprises mucoid strains producing a glucan polymer, and the other group includes strains producing a fructan polymer. The presence of a glucosyltransferase encoding gene in the glucan producing L. mesenteroides strains was assayed by PCR. Two primer sets, PF1-PF8 and GTFF-GTFR, were used to amplify internal fragment of known glucosyltransferase genes. None of the glucan-producing strains gave a positive amplicon by the primer sets used. Therefore, new tools need to be developed to broaden the range of potentially spoiling agents detected by PCR in fermented beverages.