Metabolic, Organoleptic and Transcriptomic Impact of Saccharomyces cerevisiae Genes Involved in the Biosynthesis of Linear and Substituted Esters

Esters constitute a wide family of volatile compounds impacting the organoleptic properties of many beverages including wine and beer. They can be classified according to their chemical structure. Higher Alcohols Acetate differ from Fatty Acids Ethyl Esters whereas a third group, Substituted Ethyl Esters, contributes to the fruitiness of red wines. Derived from yeast metabolism, the biosynthesis of Higher Alcohols Acetates and Fatty Acids Ethyl Esters has been widely in-vestigated at the enzymatic and genetic level. In this work, we confirmed their effective contri-bution in the fruity perception in young red wines by evaluating the effect of their depletion by chemical and sensorial analyses. As previously reported, two pairs of esterases respectively en-coded by the paralogue genes (ATF1, ATF2) and (EEB1 and EHT1) are mostly involved in the bi-osynthesis of Acetate of Higher alcohols and Fatty Acids Ethyl Esters. However, those esterases have a moderate effect on the biosynthesis of Substituted Ethyl Esters that depends to another pair of genes, MGL2 and YJU3 encoding for mono-acyl lipases. These new findings complete our un-derstanding of esters metabolism in the context of wine alcoholic fermentation. In order to evaluate the sensorial impact of esters we attempted to produce a red wine without esters by generating a multiple deletion strain. Surprisingly, we failed to abolish all the esterase activities revealing unsuspected physiological consequences of ester biosynthesis routes. A preliminary RNA-seq analysis depicted the overall impact of the multiple deletion of ATF1, ATF2, EEB1 and EHT1 that triggers the expression shift of 1124 genes involved in nitrogen and lipid metabolism but also chromatin organization and histone acetylation, suggesting an unsuspected regulatory role of ester metabolism