Isolation, selection, and characterization of highly ethanol-tolerant strains of Oenococcus oeni from south Catalonia

Resumen

Twenty-one strains of Oenococcus oeni were isolated during the malolactic fermentation of wines from south Catalonia. Due to their high ethanol tolerance (14 %, or more), these strains may serve as promising starters. The strains were screened by assays in a wine-like medium and by their co-inoculation in wine, resulting in the selection of well-performing strains, subsequently shown not to produce the main biogenic amines and lacking the genes involved in their synthesis. The genetic diversity of the isolates was studied by multilocus sequence typing (MLST), in which seven housekeeping genes were sequenced. Although the concatenated allelic profi le of some strains was the same, the profi les obtained by random amplifi cation of polymorphic DNA together with the variable number of tandem repeats at several loci showed that none of the strains were identical. A phylogenetic tree was constructed based on MLST with the seven genes and clearly showed two phylogroups, in accordance with previous studies. The best-performing strains occurred in members of both subgroups, suggesting that the grouping of housekeeping genes is not directly related to adaptation and ethanol tolerance. [Int Microbiol 2013; 16(2):113-123]

Keywords: Oenococcus oeni; malolactic fermentation; wine production; multilocus sequence typing (MLST);
strain selection