Vitis-associated microbial communities shape the volatile profiles of fermented grape juices without altering grape varietal identity

Introduction: Vitis-specific microbial communities contribute to the volatile profile of Malbec (V. vinifera L.) early grape juice fermentations. We extended our studies to characterize the impact of alternative microbial consortia on the volatile profiles of fermenting Isabella (V. labrusca L.) grape juice.

Methods: Homologous (Isabella) or heterologous (Malbec) microbial communities were used to inoculate sterile Isabella grape juice. Volatile compounds were characterized and analyzed, at early fermentation stages, using GC-MS. Cultivable yeast species were identified using 5.8-ITS rDNA sequences.

Results: PCA analyses revealed that Vitis-specific microbial starters significantly affected the volatile profiles of fermenting Isabella grape juices. H. uvarum, H. opuntiae, and S. bacillaris were the predominant yeast species in these fermentations. PCA and HCA, based on data reported herein and in previous studies on Malbec, revealed that despite the pronounced impact of alternative microbial communities on aromatic profiles, the fermented products of Malbec and Isabella grapes retained their varietal aromatic identity.

Conclusions: Our innovative experimental approach allowed us to highlight the impact of the native grape microbiota on the volatile profile of fermented grape juices, and the dominance of grape varietal identity on these profiles. Our studies underscore the potential value of wine yeasts isolated from exotic Vitis ecosystems.