Alternative Glycerol Balance Strategies among Saccharomyces Species in Response to Winemaking Stress.

Roberto Pérez-Torrado,Jana Zemančíková,Amparo Querol,Hana Sychrová,Bruno M Oliveira

doi:10.3389/fmicb.2016.00435

Abstract

Production and balance of glycerol is essential for the survival of yeast cells in certain stressful conditions as hyperosmotic or cold shock that occur during industrial processes as winemaking. These stress responses are well-known in S. cerevisiae, however, little is known in other phylogenetically close related Saccharomyces species associated with natural or fermentation environments such as S. uvarum, S. paradoxus or S. kudriavzevii. In this work we have investigated the expression of four genes (GPD1, GPD2, STL1, and FPS1) crucial in the glycerol pool balance in the four species with a biotechnological potential (S. cerevisiae; S. paradoxus; S. uvarum; and S. kudriavzevii), and the ability of strains to grow under osmotic and cold stresses. The results show different pattern and level of expression among the different species, especially for STL1. We also studied the function of Stl1 glycerol symporter in the survival to osmotic changes and cell growth capacity in winemaking environments. These experiments also revealed a different functionality of the glycerol transporters among the different species studied. All these data point to different strategies to handle glycerol accumulation in response to winemaking stresses as hyperosmotic or cold-hyperosmotic stress in the different species, with variable emphasis in the production, influx, or efflux of glycerol.

Highlights

In the fermentation industry, especially winemaking, the resistance to osmotic stress and the ability to grow at low temperatures are required features for yeast strains (Pretorius et al, 2012)
Little is known about these stress responses in other Saccharomyces species associated with natural or fermentation environments such as S. uvarum (Naumov et al, 2002; Rementeria et al, 2003; Demuyter et al, 2004), S. paradoxus, isolated from Croatian vineyards (Redzepovic et al, 2002) or natural yeast hybrids between species of the genus Saccharomyces such as S. cerevisiae × S. kudriavzevii (Gonzalez et al, 2007) and S. cerevisiae × S. uvarum (Le Jeune et al, 2007; Pérez-Torrado et al, 2015) which may participate in the fermentative processes
In this work we studied intracellular glycerol pool balance and regulation in response to stresses that occur upon inoculating wine-related yeast species in grape musts

Summary

Introduction

Especially winemaking, the resistance to osmotic stress and the ability to grow at low temperatures are required features for yeast strains (Pretorius et al, 2012). It is known that S. cerevisiae seeks to increase intracellular glycerol content when subjected to osmotic stress or cold in vinification or standard laboratory growth conditions (Panadero et al, 2006; Petelenz-Kurdziel et al, 2013; Oliveira et al, 2014). This intracellular accumulation is very important for osmotic equilibrium during the first phase of fermentation and to act as key cryoprotector agent for adaptation to cold environments allowing cellular viability with. S. paradoxus, besides being a widely distributed yeast species mainly associated with natural environments and not very relevant in fermentations, is physiologically more similar to S. cerevisiae (Tronchoni et al, 2009)

Methods

Results

Conclusion