Unveiling the fungal diversity of Falanghina grapes and the role of autochthonous Saccharomyces and non-Saccharomyces yeasts in wine fermentation

Abstract

Falanghina, a typical wine from the Sannio (Campania region, Italy), hosts a complex fungal microbiota that significantly influences both fermentation dynamics and sensory characteristics. This study aimed to compare different metabarcoding markers for profiling fungal communities and to characterize the diversity and role of non-Saccharomyces yeasts in natural fermentations. To assess fungal diversity, three DNA barcode markers (ITS1, ITS2, and D1/D2 of 26S rDNA) [1, 2, 3] were evaluated across six Falanghina grape samples and their corresponding musts at different fermentation stages. ITS2 provided the most comprehensive taxonomic resolution, identifying 63 fungal genera, whereas ITS1 and 26S revealed 20 and 17 genera, respectively. The predominant mycobiota included Metschnikowia, Hanseniaspora, Saccharomyces, Pichia, Aureobasidium, and Starmerella. However, culture-based methods enabled the identification of additional genera, such as Candida, Wickerhamomyces, Rhodotorula, and Sarocladium, reinforcing the importance of integrating molecular and traditional approaches. A complementary study focused on the isolation and characterization of non-Saccharomyces yeasts from these fermentations. Fifty-seven biotypes were distinguished based on morpho-physiological traits and enzymatic activities, including β-glucosidase production and ethanol tolerance. ITS sequencing (ITS1-5.8S-ITS2 rDNA) [4] of strains confirmed the presence, in addition to Saccharomyces (S.) cerevisiae, of 13 non-Saccharomyces species, with Metschnikowia (M.) pulcherrima and Hanseniaspora guilliermondii being the most frequently occurring. Notably, microbial composition varied according to the grape’s terroir. Autochthonous selected strains of M. pulcherrima (MP12 and MP24) and S. cerevisiae (BIO3) in 120L vinification trials were tested. Sensory analysis revealed distinct aroma profiles: wines fermented with BIO3 alone exhibited pronounced banana notes, while MP12+BIO3 enhanced pear and exotic fruit aromas, and MP24+BIO3 contributed citrus, grapefruit, floral, and vegetal nuances. These findings highlight the value of ITS2 as a metabarcoding marker for fungal diversity analysis in wine and underscore the potential of non-Saccharomyces yeasts in modulating sensory attributes. Co-inoculation strategies with S. cerevisiae offer promising applications to improve fermentation performance and enhance the aromatic complexity of Falanghina wines.

References

[1] Rué, O., Coton, M., Dugat-Bony, E., Howell, K., Irlinger, F., Legras, J. L., Sicard, D. (2023). Peer Comm. J., 3.

[2] Bokulich, NA.; Mills, DA. (2013). Appl. Environ. Microbiol., (79:2519-2526).

[3] Figueroa-Hernández, C., Mota-Gutierrez, J., Ferrocino, I., Hernández-Estrada, Z. J., González-Ríos, O., Cocolin, L., & Suárez-Quiroz, M. L. (2019).  Int. J. Food Microbiol., 301, 41-50.

[4] Esteve-Zarzoso, B., Belloch, C., Uruburu, F., & Querol, A. (1999). Int. J. Syst. Bacteriol., 49(1), 329-337.