Isolation, identification and characterization of regional indigenous Saccharomyces cerevisiae strains

Abstract In the present work we isolated and identified various indigenous Saccharomyces cerevisiae strains and screened them for the selected oenological properties. These S. cerevisiae strains were isolated from berries and spontaneously fermented musts. The grape berries (Sauvignon blanc and Pinot noir) were grown under the integrated and organic mode of farming in the South Moravia (Czech Republic) wine region. Modern genotyping techniques such as PCR-fingerprinting and interdelta PCR typing were employed to differentiate among indigenous S. cerevisiae strains. This combination of the methods provides a rapid and relatively simple approach for identification of yeast of S. cerevisiae at strain level. In total, 120 isolates were identified and grouped by molecular approaches and 45 of the representative strains were tested for selected important oenological properties including ethanol, sulfur dioxide and osmotic stress tolerance, intensity of flocculation and desirable enzymatic activities. Their ability to produce and utilize acetic/malic acid was examined as well; in addition, H2S production as an undesirable property was screened. The oenological characteristics of indigenous isolates were compared to a commercially available S. cerevisiae BS6 strain, which is commonly used as the starter culture. Finally, some indigenous strains coming from organically treated grape berries were chosen for their promising oenological properties and these strains will be used as the starter culture, because application of a selected indigenous S. cerevisiae strain can enhance the regional character of the wines.

Characterization of autochthonous wine yeasts isolated in vineyards of the State of Paraná, Brazil / Caracterização de leveduras vínicas autóctones isoladas em vinhedos do Estado do Paraná, Brasil

The transformation of grape must into wine is a complex microbiological process and is the product of the combined action of several genera and species of yeasts, dominated in the intermediate and final stages of fermentation by an alcohol-tolerant Saccharomyces sp. Current assay characterizes 42 autochthonous yeasts, isolated from the state of Paraná, southern Brazil, according to the following oenological properties: H2S production, fermentation rate, flocculation capacity, and killer phenotype (killer, sensitive and neutral characteristics). Current analysis is the first to evaluate killer phenotype in yeasts isolated from the State of Paraná, Brazil. With regard to their oenological traits, the yeasts evaluated were not suitable for winemaking and suggested that, depending on the harvest, the winemakers may face problems during the spontaneous wine production process.

A transformação do mosto de uva em vinho é um processo microbiológico complexo, resultado da ação combinada de diferentes gêneros e espécies de leveduras, no qual, entretanto, prevalece uma levedura, Saccharomyces sp. álcool-tolerante nos estágios intermediário e final da fermentação alcoólica. O objetivo deste trabalho foi caracterizar 42 leveduras autóctones isoladas da região sul do Brasil (Estado do Paraná) de acordo com as seguintes características enológicas: produção de H2S, taxa de fermentação, capacidade de floculação e fenótipo killer (características killer, sensível e neutra). Este estudo é o primeiro a avaliar fenótipo killer em leveduras isoladas do estado do Paraná. Com relação às características enológicas, as leveduras avaliadas não se mostraram promissoras para vinificação, sugerindo que, conforme a safra, o vinicultor pode enfrentar problemas durante o processo de fermentação espontânea das uvas para a elaboração de vinho.