Wine yeast biodiversity reservoirs in the vineyard: Where does Saccharomyces live in?

GONZALEZ M.L.; CHIMENO V.; STURM M.E.; COMBINA M.; MERCADO L.A.

Bariloche

Simposio; 34th International Specialized Simposium on Yeast (34 ISSY); 2018

CONICET

It is generally accepted that the vineyard is the natural habitat of wine yeasts. However, questions such as where and how wine yeasts persist year by year in this ecosystem, sometimes hostile and highly changing, are not completely clarified. The objective of this survey was to study Saccharomyces cerevisiae populations in different vineyard niches during a biological cycle of the vine, evaluating the contribution of these niches as reservoirs of yeasts populations that are finally present in ripen grapes. Ten different plots of a cv. Malbec vineyard located in the Zona Alta del Río Mendoza (Argentina) were selected and samples were collected in 5 stages of a complete phenological cycle (from one harvest to the following one). Samples of berries, bark, buds, soil and irrigation water were collected. The grapes were aseptically crushed whereas the other samples were introduced into sterile grape must (24° Brix, pH 3.5). All the musts were incubated at 25°C until 75% of the sugars were consumed and S. cerevisiae colonies were isolated and molecularly typed by interdelta-PCR. Similarity´s coefficients were estimated and dendrograms were performed to understand strain clustering and their molecular relationships using UPGMA. Results showed that each stage had a different number and diversity of S. cerevisiae strains. The grapes in both harvests showed a high number and wide distribution of strains across the vineyard´s regions, confirming that this behaviour is only present in this stage. Along the whole cycle, the soils showed low diversity suggesting their scarce contribution as reservoirs of these yeasts. Conversely, vine buds in winter as well as barks in sprouting to harvest showed to be good reservoirs, since a wide variety/quantity of yeast were isolated from those samples. A dynamic change of S. cerevisiae population was observed in the evaluated cycle, clustering according to their different isolation niches.