The aim of this study was to evaluate fifty-three Lactobacillus plantarum isolates obtained from a Patagonian red wine, molecularly identified and typified using RAPD analysis, in order to select starter cultures for malolactic fermentation (MLF). The results obtained suggest a considerable genetic diversity, taking into account that all L. plantarum isolates were obtained from one cellar and one vintage. Based on the capacity to tolerate a concentration of 14 % ethanol in MRS broth for 2 days, eight isolates were selected for the subsequent analysis. The incidence of various wine stress factors (ethanol, acid pH, lysozyme and sulfur dioxide) on isolates growth was studied. Besides, glucosidase and tannase activities were evaluated, and the presence of genes involved in the synthesis of biogenic amines was examined by PCR. A previously characterized indigenous Oenococcus oeni strain was included with comparative purposes. Differences in technologically relevant characteristics were observed among the eight L. plantarum selected isolates, revealing an isolate-dependent behavior. Detectable glucosidase and tannase activities were found in all isolates. The presence of genes encoding histidine and tyrosine descarboxylases and putrescine carbamoyltransferase was not detected. The ability of L. plantarum isolates to grow and consume L-malic acid in simulated laboratory-scale vinifications revealed that two of them could be considered as possible MLF starter cultures for Patagonian red wines. These isolates will be subjected to further analysis, for a final winery technological characterization.

The performance of Patagonian Lactobacillus plantarum and Oenococcus oeni strains as malolactic starter cultures was compared. Two autochthonous strains of each species were selected, based on the presence of aroma-related genes, and inoculated in sterile wine of high ethanol content. The effects of initial inoculum size and pre-acclimation treatment on the efficiency of malolactic fermentation (MLF) were analyzed for each strain. O. oeni strains were able to successfully conduct the MLF only when the inoculum concentration was higher than 1.10 8 CFU/mL and cells were acclimated in sublethal ethanol concentrations. The increase of ethanol concentration in the acclimation medium also improved the kinetics of malic acid consumption. Successful MLF with L. plantarum strains required lower inocula and no pre-acclimation treatment. In addition, these strains showed a better profile of aroma-related genes than O. oeni. L. plantarum strains appeared to be more efficient than O. oeni strains as candidates for malolactic starter cultures to be used in Patagonian red wines.

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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.

Background and Aims Information regarding the composition and dynamics of microbial communities throughout winemaking is always valuable to control the process and contributes to improving the quality of wine. The aims of this work were to analyse the diversity of lactic acid bacteria (LAB) species present during the spontaneous malolactic fermentation (MLF) of Patagonian red wines, and to isolate and identify native LAB species. Methods and Results Samples of Merlot and Pinot Noir wines were collected during three vintages at one commercial cellar. Through polymerase chain reaction (PCR)‐rpoB/denaturing gradient gel electrophoresis (DGGE), it was possible to identify 15 LAB species and through PCR‐16S rRNA V3 region/DGGE, 11 LAB species, during spontaneous MLF of these wines, mostly, Oenococcus oeni and Lactobacillus plantarum. These two species were also largely recovered by culture and analysed by the random amplified polymorphic DNA–PCR technique. Isolates of these two LAB species exhibited considerable genotypic heterogeneity. Conclusions The prevalence of O. oeni and Lb. plantarum in all samples suggests that both species are involved in leading the spontaneous MLF of these Patagonian wines. The analysis of the LAB microbiota in wine by PCR‐DGGE using two gene regions enabled addition to the number of species that can usually be detected during MLF. Significance of the Study The study offered a more complete knowledge of the LAB community present in wines in a cellar in the Argentine Patagonia during the spontaneous MLF. Our findings are particularly relevant, because they contribute to the possibility of designing an MLF starter composed of native strains of Lb. plantarum and O. oeni.