Apresentação efectuada na Reunião Geral da " Organisation International de la Vigne et du Vin", 83, Paris, 2003.In order to obtain a better understanding of potential environmental risks associated to the use of genetically engineered winery yeast strains, a large-scale study was realized to assess their fate in the natural environment in different geographical localizations, using non-modified commercially available yeast strains as a model. The present study aims to evaluate the industrial starter yeasts’ ability to survive and spread in nature, and become part of the natural microflora of musts. In 6 different vineyards (3 in Portugal and 3 in France) that used the same industrial yeast strain(s) continuously in the last 5 years, sampling sites were chosen and grapes were collected in a pre- and post-harvest campaign. Towards the end of the spontaneous fermentations, the composition of the yeast flora was determined by different typing methods (PCR-amplification of ∂-sequences, pulse field electrophoresis, RFLP of mitochondrial DNA, and microsatellite typing). The overall duration of these studies is 3 years, and the results obtained for the first two years showed that in Portugal, about 27% of the 930 isolates collected in 2001 and 2002 had identical typing patterns to the winery’s starter yeast, but those isolates were derived from sites in proximity to the winery (20 – 40 m), close to sites with water runoff coming from the wineries. In France, where the samples were collected in a distance of 100 to 1000 m from the winery, only 2% of 1710 isolates collected in 2001 and 2002 revealed identical genetic patterns to the used industrial yeasts. In global terms the obtained results showed that the dissemination of commercial strains in the ecosystem of a vineyard occurs in a limited space and time frame.Instituto de Cooperação Cientifica e Tecnológica Internacional
French Embassy in Lisbon (Project n.º 657C2)
