Phenotypic characterization of strains of S. cerevisiae with higher production of aromatic alcohols.

Identifier:  TFG:2233

Handle: https://hdl.handle.net/20.500.11797/TFG2233

Authors:  Ferré Alañá, Dária

Abstract:
Saccharomyces cerevisiae it’s a unicellular yeast commonly used in biotechnology research. The aim of this study was to characterize two strains of S. cerevisiae (B and C) phenotypically which provide from the same parental strain, A. These strains are known to produce a high quantity of aromatic alcohols: as 2-pheniletanol (2-PheOH), Triptophol (TrpOH) and Tyrosol (TyrOH), respectively. Our research was carried out with different fermentations in order to evaluate their growth kinetics depending on two different musts (one under standard conditions and another under a high concentration of aromatic precursors (5x)). Moreover, to see whether a high production of aromatic alcohols induced a change on their behaviour, a study of the filament growth was also realised. Finally, we also determined the presence of melatonin, a compound derived from Tryptophan and which has recently been related to yeasts. Our results have shown a high production of 2-PheOH in both strains, and TrpOH in B and TyrOH in C, hence an increase in the synthesis of these alcohols have been specifically reported in musts under precursors 5x conditions. Consequently, the presence of 2-PheOH enhances the final characteristics of the wine as it provides floral aromas to it. On the other hand, the presence of melatonin was not detected and our studies have shown that all strains form pseudo-hyphae when cultivated in a medium with low nitrogen concentration as well as when they invade. To conclude, the improved strains have been reported to be interesting in oenological applications due to their capacity to enhance organoleptic characteristics in rose and white wines.