Non-canonical regulation of glutathione and trehalose biosynthesis characterizes non-Saccharomyces wine yeasts with poor performance in active dry yeast production.

Esther Gamero-Sandemetrio,Emilia Matallana,Rocío Gómez-Pastor,Lucía Payá-Tormo,Agustín Aranda

doi:10.15698/mic2018.04.624

Abstract

Several yeast species, belonging to Saccharomyces and non-Saccharomyces genera, play fundamental roles during spontaneous must grape fermentation, and recent studies have shown that mixed fermentations, co-inoculated with S. cerevisiae and non-Saccharomyces strains, can improve wine organoleptic properties. During active dry yeast (ADY) production, antioxidant systems play an essential role in yeast survival and vitality as both biomass propagation and dehydration cause cellular oxidative stress and negatively affect technological performance. Mechanisms for adaptation and resistance to desiccation have been described for S. cerevisiae, but no data are available on the physiology and oxidative stress response of non-Saccharomyces wine yeasts and their potential impact on ADY production. In this study we analyzed the oxidative stress response in several non-Saccharomyces yeast species by measuring the activity of reactive oxygen species (ROS) scavenging enzymes, e.g., catalase and glutathione reductase, accumulation of protective metabolites, e.g., trehalose and reduced glutathione (GSH), and lipid and protein oxidation levels. Our data suggest that non-canonical regulation of glutathione and trehalose biosynthesis could cause poor fermentative performance after ADY production, as it corroborates the corrective effect of antioxidant treatments, during biomass propagation, with both pure chemicals and food-grade argan oil.

Highlights

Grape must fermentation is a complex biochemical process in which diverse yeasts, including Saccharomyces and nonSaccharomyces species, play fundamental roles in transforming grape sugars into ethanol, carbon dioxide, and hundreds of other secondary products
We recently identified a set of biochemical parameters, analyzed after dehydration, which allowed the prediction of physiologically relevant phenotypes for wine S. cerevisiae strains [11], and we demonstrated that a low level of oxidative defense characterizes deficiently performing strains
Deficient oxidative defenses in non-Saccharomyces species cause inappropriate fermentative performance for active dry wine yeast production Five non-Saccharomyces wine yeast strains were selected according to their physiology and potential contribution to wine organoleptic properties, and were tested for performance during and after active dry yeast (ADY) production by assaying biomass yield and fermentation capacity in comparison to the efficient commercial S. cerevisiae wine strain T73 (Table 1)

Summary

Introduction

Grape must fermentation is a complex biochemical process in which diverse yeasts, including Saccharomyces and nonSaccharomyces species, play fundamental roles in transforming grape sugars into ethanol, carbon dioxide, and hundreds of other secondary products. Non-Saccharomyces ADY usually displays poor fermentative capacity, and the production process in molasses medium gives low biomass yields Both biomass propagation and dehydration in industrial ADY production of S. cerevisiae strains have been reported to cause cellular oxidative stress, and negatively affect performance [810]. We proposed using three pure antioxidant molecules (ascorbic, caffeic and oleic acids), and argan oil as a foodgrade natural antioxidant, in industrial processes that involve high cellular oxidative stress, such as the biotechnological production of dry starters [14]. Antibacterial, antiviral, anti-inflammatory, anticancer and antioxidant activities have been described for caffeic acid in several organisms [17,18,19,20] At low doses, it suppresses lipid peroxidation [17] and blocks ROS [19]. Argan oil is an example of a natural product rich in antioxidants, which is commercialized in both cosmetic and food grades, and displays antiproliferative, antidiabetic and cardiovascular risk-preventive effects [2425]

Objectives

Methods

Results

Conclusion