The phenotypic characterization of yeast strains to stresses inherent to wine fermentation in warm climates.

Abstract

Climate change is exerting an increasingly profound effect on grape composition, microbiology, chemistry and the sensory aspects of wine. Identification of autochthonous yeasts tolerant to stress could help to alleviate this effect. Tolerance to osmotic pressure, ethanol and pH of 94 Saccharomyces cerevisiae strains and 29 strains non-Saccharomyces from the warm climate region DO 'Vinos de Madrid' (Spain) using phenotypic microarray and their fermentative behaviour were studied. The screening highlighted 12 strains of S.cerevisiae isolated from organic cellars with improved tolerance to osmotic stress, high ethanol concentrations and suitable fermentative properties. Screening of non-Saccharomyces spp. such as Lanchacea thermotolerans, Torulaspora delbrueckii, Schizosaccharomyces pombe and Mestchnikowia pulcherrima also highlighted tolerance to these stress conditions. This study confirmed the adaptation of native strains to the climatic conditions in each area of production and correlated these adaptations with good fermentation properties. Screening has revealed that identifying yeast strains adapted to fermentation stresses is an important approach for making quality wines in very warm areas. The results have special relevance because it is a pioneering study that has approached the problem of climate change for wines from a microbiological aspect and has analysed the situation insitu in wineries from a warm climate zone. Resistant strains were found with good biological properties; studying these strains for their stress response mechanisms during fermentation will be of interest to the wine making industry.