Behaviour during Malolactic Fermentation of Three Strains of Oenococcus oeni Used as Direct Inoculation and Acclimatisation Cultures

The behaviour in malolactic fermentation (MLF) of an autochthonous strain of Oenococcus oeni, C22L9,isolated from a winery in Castilla-La Mancha (Spain), and of two other commercial strains of O. oeni, PN4and Alpha (Lallemand Inc.), inoculated by direct inoculation (MBR®) and after a short acclimatisationphase (1-STEP®), was studied. Strain C22L9 carried out MLF slightly faster than the two other commercialstrains, leading to a lower increase in volatile acidity and in 2,3-butanedione and 3-hydroxy-2-butanoneconcentrations, a higher lactic acid content, lower degradation of citric acid and increased degradation ofethanol. No great differences were observed in the duration of MLF, although the acclimatisation cultureswere slightly faster, or in the composition of the wines when using the O. oeni strains in the form of MBR®or 1-STEP® cultures. The tasters did not detect significant differences in the wines obtained from the samestrain of O. oeni in the two inoculation formats

Genomic diversity of Oenococcus oeni populations from Castilla La Mancha and La Rioja Tempranillo red wines

The Oenococcus oeni populations of Tempranillo wines from Castilla La Mancha and La Rioja winemaking regions were analysed from one to three years and up to ten wineries. The objective was to evaluate the genetic variability and the O.oeni population structure. For this purpose a MLST scheme based on four loci (. gyrB, purK, pgm and recP genes) and PFGE with SfiI restriction enzyme were developed for later combination. The results showed an O.oeni population completely adapted to winemaking regions. Apurifying selection influenced the genes evolution, especially recP that along with purK were the most interesting loci to analyse the genetic variability of the isolates. In this way linkage disequilibrium and intergenic and intragenic recombination were determined between isolates. PFGE typing with UPGMA data were not coincident with the phylograms assessed for MLST by Maximum likelihood and combination of both techniques differentiated all the isolates as strains. Those results led the research to conclude that O.oeni population from CM and LR was a panmictic population with a slight clonal evolution, so subpopulations could not be described. A broader study including more winemaking regions with different grape varieties and distinct ways of elaborating would be interesting to complete the knowledge about O.oeni populations. © 2015 Elsevier Ltd