Genetic and phenotypic intraspecific variability of non-Saccharomyces yeasts populations from La Rioja winegrowing region (Spain)

Abstract

Aims: To determine the intraspecific genetic diversity within five non-Saccharomyces yeast species and the diversity in phenotypic characteristic related to their technological properties. Methods and Results: Seventy-one non-Saccharomyces yeasts isolated from different fermentations and facilities of the DOCa Rioja (Spain) belonging to five different wine species (Torulaspora delbrueckii, Lachancea thermotolerans, Metschnikowia pulcherrima, Zygosaccharomyces bailii and Williopsis pratensis) were subjected to clonal characterization by RAPD-PCR, which evidenced wide diversity between them. They were also submitted to a screening for some oenological traits related to the improvement of the aroma of the wine and yeast development in musts. Strains within the same species showed different enzyme activities, tolerated different levels of SO2 and possessed different killer phenotypes. These characteristics made them adjust better or worse to specific vinification processes or wine quality criteria. Conclusions: A significant genetic and phenotypic variation within the non-Saccharomyces species studied was found, which makes necessary to carry out a selection process in each one. Significance and Impact of the Study: Williopsis pratensis, a species that has not been thoroughly explored, may deserve further consideration for oenological applications. Due to the wide range of variation within species, the strains adaptation to the SO2 levels in musts has to be taken into account in selection processes.