Phenotypic and genomic differences among S. cerevisiae strains in nitrogen requirements during wine fermentations

Ying Su,Laura G Macías,José María Heras,Amparo Querol,José Manuel Guillamón

doi:10.1016/j.fm.2020.103685

Abstract

Nitrogen requirements by S. cerevisiae during wine fermentation are highly strain-dependent. Different approaches were applied to explore the nitrogen requirements of 28 wine yeast strains. Based on the growth and fermentation behaviour displayed at different nitrogen concentrations, high and low nitrogen-demanding strains were selected and further verified by competition fermentation. Biomass production with increasing nitrogen concentrations in the exponential fermentation phase was analysed by chemostat cultures. Low nitrogen-demanding (LND) strains produced a larger amount of biomass in nitrogen-limited synthetic grape musts, whereas high nitrogen-demanding (HND) strains achieved a bigger biomass yield when the YAN concentration was above 100 mg/L. Constant rate fermentation was carried out with both strains to determine the amount of nitrogen required to maintain the highest fermentation rate. Large differences appeared in the analysis of the genomes of low and high-nitrogen demanding strains showed for heterozygosity and the amino acid substitutions between orthologous proteins, with nitrogen recycling system genes showing the widest amino acid divergences. The CRISPR/Cas9-mediated genome modification method was used to validate the involvement of GCN1 in the yeast strain nitrogen needs. However, the allele swapping of gene GCN1 from low nitrogen-demanding strains to high nitrogen-demanding strains did not significantly influence the fermentation rate.

Highlights

In modern oenology, a common practice followed to conduct wine fermentation is inoculating commercial wine yeast to grape must to ensure wine quality
The nitrogen sources that can be utilised by yeast to support growth and 35 fermentation are defined as yeast assimilable nitrogen (YAN)
Their nitrogen requirements were further verified by competition

Summary

Introduction

In modern oenology, a common practice followed to conduct wine fermentation is inoculating commercial wine yeast to grape must to ensure wine quality. strains are selected by experienced oenologists to serve difference fermentation purposes. Some of the most substantial features to be considered in yeast selection are their. The right yeast strains can 23 help oenologists to compensate any defects and enhance the merits of grape must. Nitrogen is one of the most important nutrients for yeast, and its availability in grape must is a key parameter for the wine fermentation progress. The nitrogen sources that can be utilised by yeast to support growth and 35 fermentation are defined as yeast assimilable nitrogen (YAN).

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