Rethinking mixed fermentations: why yeast-yeast interactions matter in wine

Abstract

Yeast interactions during microbial fermentations represent a central topic in understanding the dynamics of microbial populations including their metabolic exchanges and the consequences for the final composition of wine. Recent studies have shown that metabolomes produced in co-cultures do not simply reflect the addition of individual metabolisms, they exhibit interaction-specific metabolic signatures. High-resolution metabolomic analyses have revealed non volatiles compounds that are absent in pure cultures, providing direct evidence of emergent metabolic responses resulting from yeast coexistence1-4. Additionally, through their metabolic interactions, yeast coexistence leads to a significant diversification of the aromatic profile of wines, characterized by both quantitative and qualitative changes in fermentative volatile compounds, resulting in perceivable sensory differences and increased wine complexity4. Esters, fatty acids and phenol families were identified as affected. One of the yeast interactions revealed through metabolomic analysis is the competition for nutrient. Indeed, the redistribution of fluxes through the central nitrogen metabolism occurring as part of interactions between yeast have been shown2. Our investigations further demonstrate that parameters often considered secondary, such as the initial physiological state of the yeasts, the mode and timing of inoculation, and the requirement for physical cell contact, actually play a major role in interaction expression1–6. Importantly, the impact of yeast interactions varies not only between species but also within a single species, including both Saccharomyces and non-Saccharomyces yeasts4–7. The divergent metabolic responses and fermentation trajectories observed highlight a previously underappreciated level of intra-specific variability challenging current strain selection strategies in mixed fermentations. Together these findings demonstrate that yeast interactions cannot be predicted from species identity alone. Overall, these results demonstrate that yeast interactions strongly influence microbial dynamics and the final composition of wines including non volatile, volatile and sensory profiles. They open new perspectives for optimizing mixed fermentations according to technological or sensory objectives and underscore the need for integrative, systems-level approaches to fully understand microbial interactions.

References

(1) Bordet, F.; Romanet, R.; Bahut, F.; Ferreira, V.; Peña, C.; Julien-Ortiz, A.; Roullier-Gall, C.; Alexandre, H. Impact of Saccharomyces Cerevisiae Yeast Inoculation Mode on Wine Composition. Food Chem. 2024, 441, 138391.

(2) Bordet, F.; Romanet, R.; Bahut, F.; Ballester, J.; Eicher, C.; Peña, C.; Ferreira, V.; Gougeon, R.; Julien-Ortiz, A.; Roullier-Gall, C. Expanding the Diversity of Chardonnay Aroma through the Metabolic Interactions of Saccharomyces Cerevisiae Cocultures. Front. Microbiol. 2023, 13, 1032842.

(3) Petitgonnet, C.; Klein, G. L.; Roullier-Gall, C.; Schmitt-Kopplin, P.; Quintanilla-Casas, B.; Vichi, S.; Julien-David, D.; Alexandre, H. Influence of Cell-Cell Contact between L. Thermotolerans and S. Cerevisiae on Yeast Interactions and the Exo-Metabolome. Food Microbiol. 2019, 83, 122–133. https://doi.org/10.1016/j.fm.2019.05.005.

(4) Roullier-Gall, C.; Bordet, F.; David, V.; Schmitt-Kopplin, P.; Alexandre, H. Yeast Interaction on Chardonnay Wine Composition: Impact of Strain and Inoculation Time. Food Chem. 2022, 374, 131732.

(5) Roullier-Gall, C.; David, V.; Hemmler, D.; Schmitt-Kopplin, P.; Alexandre, H. Exploring Yeast Interactions through Metabolic Profiling. Sci. Rep. 2020, 10 (1), 6073. https://doi.org/10.1038/s41598-020-63182-6.

(6) Puyo, M.; Scalabrino, L.; Romanet, R.; Simonin, S.; Klein, G.; Alexandre, H.; Tourdot-Maréchal, R.; Puyo, M.; Scalabrino, L.; Romanet, R.; Simonin, S.; Klein, G.; Alexandre, H.; Tourdot-Maréchal, R. Competition for Nitrogen Resources: An Explanation of the Effects of a Bioprotective Strain Metschnikowia Pulcherrima on the Growth of Hanseniaspora Genus in Oenology. Foods 2024, 13 (5). https://doi.org/10.3390/foods13050724.

(7) Bordet, F.; Roullier-Gall, C.; Ballester, J.; Vichi, S.; Quintanilla-Casas, B.; Gougeon, R. D.; Julien-Ortiz, A.; Kopplin, P. S.; Alexandre, H. Different Wines from Different Yeasts?“Saccharomyces Cerevisiae Intraspecies Differentiation by Metabolomic Signature and Sensory Patterns in Wine.” Microorganisms 2021, 9 (11), 2327.