Tailoring yeast and bacterial consortia to modulate wine fermentation profiles

Wine results from complex interactions among microorganisms during fermentation, which produce a variety of metabolites, including secondary metabolites derived from aromatic amino acids (AADC) that influence wine quality, stability and bioactivity. Both yeast species and lactic acid bacteria (LAB) can contribute to the formation of these aromatic compounds, highlighting the need to study winemaking as a network of microbial interactions that shape wine's metabolic and analytical profiles. This study aimed to select yeast and LAB strains based on their potential to produce specific AADC compounds, such as tyrosol (TyrOH) and hydroxytyrosol (HT), and to design microbial consortia to enhance their production in wine. Individual screenings of multiple strains of S. cerevisiae, non-Saccharomyces (non-Sac) and LAB were carried out in synthetic must enriched fivefold with aromatic amino acids, quantifying TyrOH and HT production. Two strains each of S. cerevisiae, Zygosaccharomyces rouxii and Oenococcus oeni were selected for their higher AADC production and tested in mixed fermentation strategies combining these microorganisms. Fermentation approaches included single fermentations or co-inoculation of non-Sac and LAB strains, followed by sequential inoculation of S. cerevisiae. Organic acids, microbial population dynamics and AADC production were monitored across different proposed consortia. The combination of S. cerevisiae Lalvin CLOS and Z. rouxii CW96 produced the highest concentrations of HT. All co-inoculations with LAB completed malolactic fermentations efficiently, without increasing acetic acid levels. These results highlight the potential of controlled multi-species fermentations to modulate wine composition and support the development of microbial consortia aimed at improving functional and metabolic profiles.