Deciphering wine fermentation through microbiota transplantation and synthetic yeast communities.

Microbial communities play a central role in fermentation dynamics and in wine quality, by driving the fermentation process and shaping the sensory and chemical profiles of wine. Consequently, although considerable attention has been given to inoculation strategies, including commercial starter cultures, pied-de-cuve, and spontaneous fermentation, the impact of transplanting an entire microbial community independently of its original matrix has not yet been evaluated. This study compared grape berry surface microbiota transplantation by berry rinsing with the traditional pied-de-cuve approach, using two grape varieties, Artaban and Carignan. Mycobiota dynamics were monitored by ITS metabarcoding throughout fermentation, complemented by synthetic microbial consortia (SynComs), fermentation kinetics, stress tolerance assays, and volatile aroma analyses. Grape cultivar was the main driver of microbial community composition, followed by inoculation strategy. Berry-rinse fermentations preserved a richer and more diverse microbiota, whereas pied-de-cuve inoculation enriched fermentative yeasts, accelerated microbial succession, and promoted earlier establishment of Saccharomyces cerevisiae. These differences were associated with distinct fermentation kinetics and volatile aroma profiles, with pied-de-cuve fermentation tending to produce higher concentrations of volatile compounds. In parallel, SynComs were assembled to investigate the ecological behavior and fermentation performance of dominant indigenous fermentative yeasts under controlled conditions. Hanseniaspora opuntiae exhibited greater persistence during fermentation than Hanseniaspora uvarum, consistent with its higher ethanol tolerance. Although both species produced broadly similar volatile profiles, subtle differences were observed for specific aroma compounds. In addition, the greater ecological fitness of H. opuntiae, particularly under elevated temperature conditions, suggests that this species may become increasingly important under future climate conditions.