Diversity and geographical distribution of indigenous Saccharomyces cerevisiae strains from the Comahue winegrowing region (Argentinean North Patagonia)

LOPES, CHRISTIAN; ZAJONSKOSVKY, I.; BARBAGELATA, R.J.; RODRIGUEZ,M.E.; LAVALLE, L.; SANGORRIN, M.P.; CABALLERO, A.C.

Rosario

Congreso; SAMIGE; 2008

SAMIGE

One of the most significant technological advances in winemaking has been the control of themicrobiological process by grape must inoculation using selected Saccharomyces cerevisiaestrains. Today, the use of indigenous wine yeasts selected from each winegrowing area is awidespread enological practice. These local yeasts are presumed to be more competitive thancommercial yeasts because they are better adapted to the ecological and technological featuresof their own winegrowing area. Comahue region is one of the most Southern winegrowingregions in the world. In this region, located in Argentinean North Patagonia, both spontaneousand conducted grape juice fermentations are carried out to produce mostly dry red wines.The aim of this work was to characterize the indigenous wine Saccharomyces cerevisiaediversity within the Comahue region in order to develop regional red wine starters. Six cellarslocated in four different winegrowing areas, Colorado (RC) and Negro (HC) River Upper Valleys, in Rio Negro Province, and El Chañar (Ch) and Añelo (Ñ) in Neuquen province, were selected and 19 spontaneous and conduced red wine fermentations carried out in them during 2002 to 2006 vintages were sampled at different stages. Yeasts were isolated onto YEPD agar plates and 523 isolates assigned to S. cerevisiae species using ITS1-5.8S-ITS2 PCR-RFLP method were characterized at the strain level using combined mtDNA-RFLP and killer behaviour againstK2 type toxin patterns. Twenty three commercial starters often used in the cellars were also characterized at strain level.Ninety six different combined patterns, i.e. 96 strains, were discriminated among the isolatesanalyzed from which eight corresponded to commercial strains and they represented the 45% ofthe total biomass (233 isolates). This results evidences that some commercial S. cerevisiaestrains are capable to remain in the environmental winery over a large period of time. On theother hand, the results showed a great diversity of enological indigenous strains of S. cerevisiae(88 different patterns among 290 isolates, R=3,29) and a higher variability within the S.cerevisiae population associated with CR area (R=2.08) than the ones associated with HC(R=3,53), Ch (R=3,84) and Ñ (R=7,00). Additionally, all spontaneous fermentations were carried out and completed by a limited number of dominating strains (two to three) associated with a variable number of secondary strains. Some of these dominant indigenous strains remained in the environmental cellar over the period of time studied and they were also identified inconduced fermentations. Finally, the evaluation of the relatedness among strains using PrincipalCoordinates Analysis from combined molecular and killer data allowed the clustering of theindigenous S. cerevisiae strains into four populations significantly related to their origin areas.This finding suggests the need to select specific strains from each particular area withinComahue region.