Genomic and phenomic analysis of Hanseniaspora vineae provides insights for understanding yeast fermentation flavors that contribute to wine quality.

Identifier:  imarina:5132420

Handle: https://hdl.handle.net/20.500.11797/imarina5132420

Authors:  Giorello, F; Valera, MJ; Martin, V; Parada, A; Salzman, V; Camesasca, L; Fariña, L; Boido, E; Medina, K; Dellacassa, E; Berna, L; Aguilar, PS; Mas, A; Gaggero, C; Carrau, F

Abstract:
Hanseniaspora is the main genus of the apiculate yeast group that represents about 70% of the grape-associated microflora. Hanseniaspora vineae is emerging as a promising species for quality wine production compared to other non-Saccharomyces. Wines produced by H. vineae with Saccharomyces cerevisiae consistently exhibit more intense fruity flavours and complexity than wines produced by S. cerevisiae alone. In this work, genome sequencing, assembling and phylogenetic analysis of two strains of H. vineae shows that it is a member of the Saccharomyces complex and it diverged before the Whole Genome Duplication (WGD) event from this clade. Specific flavour gene duplications and absences were identified in the H. vineae genome, as compared to 14 fully sequenced industrial S. cerevisiae genomes. The increased formation of 2-phenylethyl acetate and phenylpropanoids such as 2-phenylethyl and benzyl alcohols might be explained due to gene duplications of H. vineae aromatic amino acid aminotransferases (ARO8, ARO9) and phenylpyruvate decarboxylases (ARO10). Transcriptome and aroma profiles under fermentation conditions confirmed these genes were highly expressed at the beginning of stationary phase coupled to the production of their related compounds. The extremely high level of acetate esters produced by H. vineae compared to S. cerevisiae is consistent with the identification of six novel proteins with alcohol acetyltransferase (AATase) domains. The absence of the branched-chain-amino-acid transaminases (BAT2) and acyl-CoA/ethanol O-acyltransferases (EEB1) genes, correlates with H. vineae reduced production of branched-chain higher alcohols, fatty acids and ethyl esters, respectively. Our study provides sustenance to understanding and potentially utilizing genes that determine fermentation aromas. Importance The huge diversity of non-Saccharomyces yeasts in grapes is dominated by the apiculate genus Hanseniaspora. Two native strains of H. vineae applied to winemaking due to their high oenological potential in aroma and fermentation performance, were selected to obtain high quality genomes. Here, we present a phylogenetic analysis, and the complete transcriptome and aroma metabolome of H. vineae during three fermentation steps. This species produced significantly richer flavour compound diversity compared to Saccharomyces, such as benzenoids, phenylpropanoids, and acetate derived compounds. The identification of six proteins, different from S. cerevisiae ATF, with diverse acetyl transferase domains in H. vineae offers a relevant source of native genetic variants for this enzymatic activity. The discovery of benzenoid synthesis capacity in H. vineae provides a new eukaryotic model to dilucidate an alternative pathway to that catalysed by plants' phenylalanine lyases.