Growth and consumption of L-malic acid in wine-like medium by acclimated and non-acclimated cultures of Patagonian Oenococcus oeni strains.

Five Oenococcus oeni strains, selected from spontaneous malolactic fermentation (MLF) of Patagonic Pinot noir wine, were assessed for their use as MLF starter cultures. After the individual evaluation of tolerance to some stress conditions, usually found in wine (pH, ethanol, SO2, and lysozyme), the behavior of the strains was analyzed in MLO broth with 14 % ethanol and pH 3.5 in order to test for the synergistic effect of high ethanol level and low pH and, finally, in a wine-like medium. Although the five strains were able to grow in MLO broth under low pH and/or high ethanol, they must be acclimated to grow in a wine-like medium. Additionally, glycosidase and tannase activities were evaluated, showing differences among the strains. The potential of the strains to ferment citrate was tested and two of the five strains showed the ability to metabolize this substrate. We did not detect the presence of genes encoding histidine, tyrosine descarboxylase, and putrescine carbamoyltransferase. All the strains tested exhibited good growth capacity and ability to consume L-malic acid in a wine-like medium after cell acclimation, and each of them showed a particular enzyme profile, which might confer different organoleptic properties to the wine.