Functional analysis of lipid metabolism genes in wine yeasts during alcoholic fermentation at low temperature.

Maria Lopez-Malo,Rosana Chiva,Jose Guillamon,Estefani Garcia-Rios

doi:10.15698/mic2014.11.174

Abstract

Wine produced by low-temperature fermentation is mostly considered to have improved sensory qualities. However few commercial wine strains available on the market are well-adapted to ferment at low temperature (10 - 15°C). The lipid metabolism of Saccharomyces cerevisiae plays a central role in low temperature adaptation. One strategy to modify lipid composition is to alter transcriptional activity by deleting or overexpressing the key genes of lipid metabolism. In a previous study, we identified the genes of the phospholipid, sterol and sphingolipid pathways, which impacted on growth capacity at low temperature. In the present study, we aimed to determine the influence of these genes on fermentation performance and growth during low-temperature wine fermentations. We analyzed the phenotype during fermentation at the low and optimal temperature of the lipid mutant and overexpressing strains in the background of a derivative commercial wine strain. The increase in the gene dosage of some of these lipid genes, e.g., PSD1, LCB3, DPL1 and OLE1, improved fermentation activity during low-temperature fermentations, thus confirming their positive role during wine yeast adaptation to cold. Genes whose overexpression improved fermentation activity at 12°C were overexpressed by chromosomal integration into commercial wine yeast QA23. Fermentations in synthetic and natural grape must were carried out by this new set of overexpressing strains. The strains overexpressing OLE1 and DPL1 were able to finish fermentation before commercial wine yeast QA23. Only the OLE1 gene overexpression produced a specific aroma profile in the wines produced with natural grape must.

Highlights

Temperature is one of the most important parameters to affect the length and rate of alcoholic fermentation and final wine quality
We identified the genes of the phospholipid, sterol and sphingolipid pathways, which impacted on growth capacity at low temperature
We analyzed the phenotype during fermentation at the low and optimal temperature of the lipid mutant and overexpressing strains in the background of a derivative commercial wine strain

Summary

Introduction

Temperature is one of the most important parameters to affect the length and rate of alcoholic fermentation and final wine quality. Many winemakers prefer lowtemperature fermentation (10 - 15°C) for the production of white and rosé wine because it improves taste and aroma characteristics This improved quality can be attributed to the prevention of volatilization of primary aromas, and to the increased synthesis of secondary aromas. The final wine possesses greater terpenes retention, reduced higher alcohols and an increased proportion of ethyl and acetate esters in the total volatile compounds [1,2,3,4]. Another positive aspect is that low temperatures reduce the growth of acetic and lactic bacteria, making it easier to control alcoholic fermentation. The quality of those wines produced at low temperature depends on the yeast’s ability to adapt to cold

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