Must Microbiomes in Vino Nobile di Montepulciano DOCG Terroir
The microbial terroir of wine is increasingly recognized as a biological component of Protected Designation of Origin (PDO) identity, yet its direct contribution to wine composition remains poorly understood. Here, we combined shotgun metagenomics, genome-resolved analyses, culture-dependent microbial isolation, comparative metagenomics, and untargeted metabolomics to characterize grape must microbiomes from Vino Nobile di Montepulciano DOCG, a historic wine-producing region recently subdivided into twelve Additional Geographic Units. Comparative analyses with global grape must metagenomes identified a distinctive bacterial and eukaryotic signature that distinguished Montepulciano from other Italian and international wine regions. Within the production area, must microbiomes displayed geographic variation in both taxonomic composition and functional potential, with specific microbial lineages and enologically relevant enzymes showing spatially structured distributions across the territory. Functional profiling revealed the genomic potential for microbial functions associated with fermentation, aroma precursor release, ester formation, amino acid catabolism, and malolactic conversion. Integration of microbial functional profiles with metabolomic data from musts and corresponding wines showed a significant association between microbiome-encoded functional potential and wine chemical composition, independent of the initial must metabolome and fermentation strategy.  These findings indicate that geographically structured grape must microbiomes harbor distinct functional potential associated with wine chemical composition, supporting a potential biological contribution of microbial terroir to the distinctiveness of PDO wines.
The microbial terroir of wine is increasingly recognized as a biological component of Protected Designation of Origin (PDO) identity, yet its direct contribution to wine composition remains poorly understood. Here, we combined shotgun metagenomics, genome-resolved analyses, culture-dependent microbial isolation, comparative metagenomics, and untargeted metabolomics to characterize grape must microbiomes from Vino Nobile di Montepulciano DOCG, a historic wine-producing region recently subdivided into twelve Additional Geographic Units. Comparative analyses with global grape must metagenomes identified a distinctive bacterial and eukaryotic signature that distinguished Montepulciano from other Italian and international wine regions. Within the production area, must microbiomes displayed geographic variation in both taxonomic composition and functional potential, with specific microbial lineages and enologically relevant enzymes showing spatially structured distributions across the territory. Functional profiling revealed the genomic potential for microbial functions associated with fermentation, aroma precursor release, ester formation, amino acid catabolism, and malolactic conversion. Integration of microbial functional profiles with metabolomic data from musts and corresponding wines showed a significant association between microbiome-encoded functional potential and wine chemical composition, independent of the initial must metabolome and fermentation strategy.  These findings indicate that geographically structured grape must microbiomes harbor distinct functional potential associated with wine chemical composition, supporting a potential biological contribution of microbial terroir to the distinctiveness of PDO wines.