Region-associated microbial signatures persist during inoculated fermentation of Nebbiolo grapes

ABSTRACT Wine fermentation is driven by dynamic microbial communities that influence fermentation kinetics and wine composition. During fermentation, both the dominant Saccharomyces cerevisiae and diverse non- Saccharomyces yeasts, along with bacteria, actively contribute to metabolite and aroma formation, potentially reflecting vineyard environmental and geographic characteristics. Despite growing interest in the spatial structuring of grape-associated microbiota, knowledge remains limited regarding the persistence of these microbial signatures during inoculated fermentations. This study characterized fungal and bacterial communities during inoculated fermentations of Vitis vinifera cv. Nebbiolo grapes from multiple vineyards, integrating chemical and volatilome data. The results revealed distinct temporal dynamics and region-associated patterns in fungal and bacterial communities, together with associated differences in chemical and volatile profiles. These findings indicate that geographical differentiation of grape-associated microbial communities is maintained throughout inoculated fermentation and is associated with distinct microbial succession patterns and chemical profiles. IMPORTANCE Yeast and bacterial population dynamics during alcoholic fermentation play a decisive role in shaping wine characteristics, and the composition of microbial communities present on grapes at harvest is known to influence the fermentation process. In this study, fungal and bacterial community patterns associated with vineyard geography remained detectable throughout standardized inoculated fermentations, despite the dominance of a commercial starter culture. These persistent microbial signatures were associated with differences in microbial succession, chemical composition, and wine volatilome, supporting the concept that regional microbial imprints can remain detectable under commercial winemaking conditions.