The phenotypic heterogeneity of saccharomyces cerevisiae strains from natural environments

Abstract

Saccharomyces cerevisiae is the model organism par excellence and stands today at the forefront of molecular biology, genetics and genomics. However, as for many other laboratory model organisms, understanding of the ecological, evolutionary and population genetic features that shaped the biology of S. cerevisiae is underscored by a wealth of knowledge on molecular and cellular biology, mainly obtained from a very limited number of reference laboratory strains. In the last few years, yeast researchers developed a keen interest to identify genomic variability between wild-type yeast strains from different ecological niches or strains that are used for different technological applications. The aim of the present work was to constitute a S. cerevisiae wine yeast strain collection for the conservation of biodiversity, sustainable development of genetic resources and for the identification of strains for biotechnological applications. The S. cerevisiae strains that constitute our strain collection were obtained from grape varieties collected in the Vinho Verde appellation of origin in Portugal. Grape samples were collected in consecutive years since 2001, from multiple sampling sites of several vineyards at harvest time. A total of 2520 yeast isolates were obtained during 2001 – 2006, and were assigned to 350 different strains, based on genetic analysis by a set of highly polymorphic microsatellites. Using neural networks, a subset of 103 genetically most diverse strains was chosen for phenotypic analysis, that included growth in synthetic must media at various temperatures, utilization of carbon sources (glucose, ribose, arabinose, xylose, saccharose, galactose, rafinose, maltose, glycerol, potassium acetate and pyruvic acid), growth in ethanol containing media, evaluation of osmotic and oxidative stress resistance, H2S production and utilization of different nitrogen sources. Significant heterogeneity was apparent among strains and we identified numerous strains with the capability to grow in media containing ribose, arabinose and xylose, not previously described for S. cerevisiae.