Design of microbial consortia to improve the production of aromatic amino acid derived compounds during wine fermentation

Abstract

Wine contains secondary metabolites derived from aromatic amino acids (AADC), which can determine quality, stability and bioactivity. Several yeast species, as well as some lactic acid bacteria (LAB), can contribute in the production of these aromatic compounds. Winemaking should be studied as a series of microbial interactions, that work as an interconnected network, and can determine the metabolic and analytical profiles of wine. The aim of this work was to select microorganisms (yeast and LAB) based on their potential to produce AADC compounds, such as tyrosol and hydroxytyrosol, and design a microbial consortium that could increase the production of these AADC compounds in wines. Individual screenings of different strains of S. cerevisiae, non-Saccharomyces (non-Sac) and LAB where carried out in synthetic must with 5x of aromatic amino acids. Production of tyrosol and hydroxytyrosol was determined through HPLC-MS/MS. Two strains of S. cerevisiae, two of Zygosaccharomyces rouxii and two ofOenococcus oeni were selected for producing higher concentrations of tyrosol and hydroxytyrosol. Selected strains were then tested in different strategies of mixed inocula fermentations, combining the three microorganisms. Fermentations were done by single or co-inoculation of non-Sac and LAB strains, followed by sequential inoculation of S. cerevisiae strain. Organic acids, population dynamics and production of AADC were evaluated in the eight proposed consortia. Consortia that presented S. cerevisiae Lalvin CLOS and Z. rouxii CW96 produced highest concentrations of hydroxytyrosol (up to 3 µg/L). Moreover, all co-inoculations with LAB completed rapidly malolactic fermentations, and O. oeni did not increase acetic acid production. This study provides information on potential microbial interactions in microbial consortia that can enhance metabolic profile in winemaking.

Acknowledgements: This work has been financed by the project PDI2019-108722RB-C3. AS holds a fellowship of the Ministry of Science and Innovation (PRE2020-096645) and PGS a “Margarita Salas, María Zambrano, Recualificación” grant Spanish Ministry of Universities financed with European Union NextGenerationEU.