Dynamic changes in microbiota and mycobiota during spontaneous 'Vino Santo Trentino' fermentation.

Irene Stefanini,Davide Albanese,Claudio Donati,Agostino Cavazza,Elena Franciosi,Duccio Cavalieri,Carlotta De Filippo

doi:10.1111/1751-7915.12337

Abstract

Vino Santo is a sweet wine produced from late harvesting and pressing of Nosiola grapes in a small, well-defined geographical area in the Italian Alps. We used metagenomics to characterize the dynamics of microbial communities in the products of three wineries, resulting from spontaneous fermentation with almost the same timing and procedure. Comparing fermentation dynamics and grape microbial composition, we show a rapid increase in a small number of wine yeast species, with a parallel decrease in complexity. Despite the application of similar protocols, slight changes in the procedures led to significant differences in the microbiota in the three cases of fermentation: (i) fungal content of the must varied significantly in the different wineries, (ii) Pichia membranifaciens persisted in only one of the wineries, (iii) one fermentation was characterized by the balanced presence of Saccharomyces cerevisiae and Hanseniaspora osmophila during the later phases. We suggest the existence of a highly winery-specific 'microbial-terroir' contributing significantly to the final product rather than a regional 'terroir'. Analysis of changes in abundance during fermentation showed evident correlations between different species, suggesting that fermentation is the result of a continuum of interaction between different species and physical-chemical parameters.

Highlights

In oenology, the quality, taste and style of wine are traditionally considered to be influenced by the cultivar of the fermented grapes, geographical factors such as the vineyard mesoclimate, topoclimate and microclimate, soil geology and pedology, and the agronomic approach used (Van Leeuwen & Seguin, 2006)
To examine the dynamic changes in microbial populations driving must fermentation, three Vino Santo products were investigated from the beginning to the end of fermentation (3 months), at the Poli, Pisoni and Pedrotti wineries located in the Valle dei Laghi in Trentino, Italy
Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology, Microbial Biotechnology, 9, 195–208

Summary

Introduction

The quality, taste and style of wine are traditionally considered to be influenced by the cultivar of the fermented grapes, geographical factors such as the vineyard mesoclimate, topoclimate and microclimate, soil geology and pedology, and the agronomic approach used (Van Leeuwen & Seguin, 2006). The microbial population involved in the fermentation process has been shown to play a pre-eminent role in determining the properties of wine (Carreto et al, 2008; Renouf et al, 2002) through the production of secondary metabolites that contribute to wine aromas (Calabretti et al, 2012). Several studies have shown that the microbial population present at the moment of grape harvesting and during early fermentation belongs to the vineyard (Polsinelli et al, 1996; Barata et al, 2012), providing an alternative mechanism through which the environment may influence wine quality and taste (Lopes et al, 2002; Renouf et al, 2002; Carreto et al, 2008). Despite the fact that a part of this early stage microbiota does not survive the stressful conditions of late must fermentation, it still plays a role in shaping the entire process (Heard and Fleet, 1988)

Results

Discussion

Conclusion