TASTY

Interactions between microorganisms are at the heart of the dynamics of microbial ecosystems, as they determine both the behavior of populations and the properties of final products, as in the case of the impact of yeasts on oenological fermentation, which will serve as a model in this project. These interactions, whether positive, neutral or negative, are governed by various underlying mechanisms that are still poorly understood. This is even more complex as they may depend on genetic diversity, not only between species, but also within species. Whether it's the species level or the strain level that exerts the greatest influence. The answer to this question is of crucial importance for the efficient design of fermentation starters. Moreover, accurately identifying the nature and magnitude of interactions is a challenge, especially when they occur at low intensities. Distinguishing subtle positive interactions from simple additive effects is particularly difficult in transient regimes. As such, our project aims to use enology as an experimental method to systematically explore the relationships between a multitude of yeast strains, species and genera, while examining the impact of environmental constitution on these interactions. To achieve this goal, we will combine experimental protocols with modeling. The modeling approach consists of 1) a statistical study of the differences between models without interaction and observed data to infer new interaction terms, 2) a qualitative analysis of the dynamics of the assemblages for models with these interaction terms, and 3) back and forth between quantitative calibration of the proposed models and experiments on new consortia. This will guide us towards the most relevant choices of assemblies to test, and the optimization of the initial composition of these consortia as well as the additions of strains over time, to identify the best-performing assemblies and their operating conditions. This approach will be developed in such a way as to be applicable to other microbial systems, thus serving as a solid basis for developing a robust ecological engineering approach for yeast.