Improving the Cryotolerance of Wine Yeast by Interspecific Hybridization in the Genus Saccharomyces.

Estéfani García-Ríos,Alba Guillén,Roberto De La Cerda,Amparo Querol,José M Guillamón,Laura Pérez-Través

doi:10.3389/fmicb.2018.03232

Abstract

Fermentations carried out at low temperatures (10–15°C) enhance the production and retention of flavor volatiles, but also increase the chances of slowing or arresting the process. Notwithstanding, as Saccharomyces cerevisiae is the main species responsible for alcoholic fermentation, other species of the genus Saccharomyces, such as cryophilic species Saccharomyces eubayanus, Saccharomyces kudriavzevii and Saccharomyces uvarum, are better adapted to low-temperature fermentations during winemaking. In this work, a Saccharomyces cerevisiae × S. uvarum hybrid was constructed to improve the enological features of a wine S. cerevisiae strain at low temperature. Fermentations of white grape musts were performed, and the phenotypic differences between parental and hybrid strains under different temperature conditions were examined. This work demonstrates that hybridization constitutes an effective approach to obtain yeast strains with desirable physiological features, like low-temperature fermentation capacity, which genetically depend on the expression of numerous genes (polygenic character). As this interspecific hybridization approach is not considered a GMO, the genetically improved strains can be quickly transferred to the wine industry.

Highlights

In winemaking, fermentation at lower temperatures correlates with a fresh character and fruity notes in wines (Beltran et al, 2002; Torija et al, 2003; Molina et al, 2007)
A phenotypic analysis was performed at different temperatures (12–40◦C) to evaluate the thermotolerance differences of a collection of yeast strains belonging to diverse environmental niches and species
In lab medium (LM), Cluster 1 was mainly integrated by the strains able to grow at 40◦C (Supplementary Table S2), that is, the most tolerant strains at high temperature

Summary

Introduction

Fermentation at lower temperatures correlates with a fresh character and fruity notes in wines (Beltran et al, 2002; Torija et al, 2003; Molina et al, 2007). The non-Saccharomyces yeasts, predominant in grape juice, are rapidly outcompeted by S. cerevisiae because of their poor adaptation to Hybridization for Improving Yeast Cryotolerance increasing concentrations of ethanol, impoverishing of nutrients and the lack of oxygen (Torija et al, 2001; Beltran et al, 2002). This population dynamic can be modified by dropping the fermentation temperature, favoring the growth and survival of non-Saccharomyces species for a longer period (Salvadó et al, 2011b)

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