title: The effect of increased branched-chain amino acid transaminase activity in yeast on the production of higher alcohols and on the flavour profiles of wine and distillates.
abstract: In Saccharomyces cerevisiae, branched-chain amino acid transaminases (BCAATases) are encoded by the BAT1 and BAT2 genes. BCAATases catalyse the transfer of amino groups between those amino acids and alpha-keto-acids. alpha-Keto-acids are precursors for the biosynthesis of higher alcohols, which significantly influence the aroma and flavour of yeast-derived fermentation products. The objective of this study was to investigate the influence of BAT-gene expression on general yeast physiology, on aroma and flavour compound formation and on the sensory characteristics of wines and distillates. For this purpose, the genes were overexpressed and deleted in a laboratory strain, BY4742, and overexpressed in an industrial wine yeast strain, VIN13. The data show that, with the exception of a slow growth phenotype observed for the BAT1 deletion strain, the fermentation behaviour of the strains was unaffected by the modifications. The chemical and sensory analysis of fermentation products revealed a strong correction between BAT gene expression and the formation of many aroma compounds. The data suggest that the adjustment of BAT gene expression could play an important role in assisting winemakers in their endeavour to produce wines with specific flavour profiles.
authors.affiliation: Institute for Wine Biotechnology, Stellenbosch University, Victoria Street, Stellenbosch, South Africa.
authors.forename: Mariska
authors.initials: M
authors.lastname: Lilly
authors.forename: Florian F
authors.initials: FF
authors.lastname: Bauer
authors.forename: Gustav
authors.initials: G
authors.lastname: Styger
authors.forename: Marius G
authors.initials: MG
authors.lastname: Lambrechts
authors.forename: Isak S
authors.initials: IS
authors.lastname: Pretorius
mesh_terms: D000438:Alcohols / Q000378:metabolism*; D005285:Fermentation; D005421:Flavoring Agents / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000502:physiology*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D000637:Transaminases / Q000502:physiology*; D014920:Wine
chemical_list: D000438:Alcohols; D005421:Flavoring Agents; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; D000637:Transaminases; C101168:BAT1 protein, S cerevisiae; C101127:BAT2 protein, S cerevisiae