Evaluation of indigenous lactic acid bacteria associated with Patagonian wines for their use as malolactic starter cultures

DANAY VALDÉS LA HENS, BÁRBARA M. BRAVO-FERRADA, NATALIA S. BRIZUELA, E.E. TYMCZYSZYN, A. HOLLMANN, L. DELFEDERICO, L. SEMORILE

Tucumán

Simposio; SIBAL 2016 V International Symposium on Lactic Acid Bacteria; 2016

CERELA

During winemaking, lactic acid bacteria (LAB) guide the malolactic fermentation (MLF) which produces deacidification of wine, enhancing its microbial stability and modifying the wine aroma profile. When MLF takes place spontaneously, it is carried out by one or more indigenous LAB species present in grapes and cellars. Traditional winemaking practices encourage the use of native microbiota to conduct fermentations with the aim of enhancing regional tipicity of wines. Here we summarize the studies conducted on LAB population diversity in some Patagonian wines, as well as the methods and criteria employed to select indigenous Lb. plantarum and O. oeni strains for their potential use as malolactic starter cultures. The PCR-DGGE method, using two genome regions, was applied to describe the diversity of LAB species during spontaneous MLF. It showed the greatest amount of these species described so far in red wines. The prevalence of O. oeni and Lb. plantarum in all wine samples suggest that both species are involved in leading the spontaneous MLF of the Pinot Noir and Merlot wines tested. The genetic diversity data from Lb. plantarum and O. oeni isoltes demonstrate a considerable genotypic heterogeneity through the MLF in all vinifications studied. To select the best Lb. plantarum and O. oeni strains to be employed as starter cultures, they were subjected to various screening test: a) tolerance to low pH and high concentrations of ethanol, lysozyme and SO2, b)presence of some enzymatic activities as B glucosidase, tannase, proline imino peptidase, phenolic acid decarboxilase and citrate lyase, c) absence of genes involved in the biogenic amines synthesis. Those strains able to resist the hostile wine enviroment and to consume malic acid were selected. Also, it was evaluated the previous incubation of the strains in an acclimation medium to improve their performance to guide MLF in a wine-like medium. Lb. plantarum and O. oeni strains subjected to precious acclimation treatment exhibited better ability to grow and to consume malic acid. The physico-chemical analysis of the acclimation effect on cell surface and membrane properties showed changes at level of lipid bilayer. The Z-potential values of acclimated cells revealed modifications on the macromolecules exposed on the surface. On the other hand, the selected strains showed a particular enzyme profile, which might confer different organoleptic properties to the wine. However, Lb. plantarum strains appeared to be more efficient than O. oeni strains as candidates for MLF starter cultures.