Wine arises from the interaction of a complex microbial ecosystem with the physical-chemical matrix of grape must. Both aspects are highly determined by geographic, climatic, and vineyard and winery operational aspects. Tens to hundreds of different microbial (yeast and bacteria) species are involved in wine fermentations, and the diversity of microbial species and metabolisms taking part in the fermentation process will have a direct impact on the sensorial properties of the final wine. Spontaneous wine fermentations allow the full and progressive development of this microbial consortia through a progressive succession of species. However, as a deterministic process, Saccharomyces cerevisiae will always be the dominating yeast that will lead to the complete depletion of fermentable sugars from grape must, finishing the alcoholic fermentation.
The complexity of this microbial process has forced wine industries to use commercial inocula of selected S. cerevisiae yeast strains for a forced control of this microbial succession, with the aim to guarantee an adequate fermentation kinetics, avoiding fermentation stuck or microbial-derived wine spoilages. However, this has led to the production of highly standardized and homogenous wines worldwide, which contravenes the current consumers’ demands of wines with exalted regional characteristics, usually known as terroir-driven wines. Thus, wine industry needs a better understanding of the microbial, environmental and operational determinants of wine fermentations performance, in order to predict successful or failed processes and, thus, to take decisions based on data following precision oenology trends.
This project aims to understand, through a systems biology approach, the microbial ecosystem assembly and functioning in wine fermentations, considering the impact of the vineyard management (conventional vs. organic farming), and some winery aspects (grape must pH, SO2 addition or fermentation temperature). This will be addressed through the understanding of the microbial interactions patterns in different winemaking conditions and the molecular basis of these interactions at a transcriptional and metabolic level. Using the networks theory, we will define global interspecies interactions patterns, identifying keystone species for wine microbiome assembly, and how facilitator and competitor species may cause synergism or antagonism effects in S. cerevisiae performance. Thus, following a mixed approach of observational and mechanistic studies at macro-, meso- and microcosms levels, this project aims to model wine fermentations performance to predict the microbial dynamics, fermentation kinetics and the production of some aroma-impact wine metabolites using data from the grape must microbiome and its basic physical-chemical properties.