High-Throughput Sequencing Approach to Analyze the Effect of Aging Time and Barrel Usage on the Microbial Community Composition of Red Wines.

Dimitrios Kioroglou,Albert Mas,Maria C Portillo

doi:10.3389/fmicb.2020.562560

Abstract

Wine aged in barrels or bottles is susceptible to alteration by microorganisms that affect the final product quality. However, our knowledge of the microbiota during aging and the factors modulating the microbial communities is still quite limited. The present work uses high-throughput sequencing (HTS) techniques to deal with the meta-taxonomic characterization of microbial consortia present in red wines along 12 months aging. The wines obtained from two different grape varieties were aged at two different cellars and compared based on time of wine aging in the barrels, previous usage of the barrels, and differences between wine aging in oak barrels or glass bottles. The aging in barrels did not significantly affect the microbial diversity but changed the structure and composition of fungal and bacterial populations. The main microorganisms driving these changes were the bacterial genera Acetobacter, Oenococcus, Lactobacillus, Gluconobacter, Lactococcus, and Komagataeibacter and the fungal genera Malassezia, Hanseniaspora, and Torulaspora. Our results showed that the oak barrels increased effect on the microbial diversity in comparison with the glass bottles, in which the microbial community was very similar to that of the wine introduced in the barrels at the beginning of the aging. Furthermore, wine in the bottles harbored higher proportion of Lactobacillus but lower proportion of Acetobacter. Finally, it seems that 1 year of previous usage of the barrels was not enough to induce significant changes in the diversity or composition of microbiota through aging compared with new barrels. This is the first meta-taxonomic study on microbial communities during wine aging and shows that the microorganism composition of barrel-aged wines was similar at both cellars. These results hint at the possibility of a common and stable microbiota after aging in the absence of exogenous alterations. Further corroborations on the current outcome would be valuable for the comparison and detection of microbial alterations during aging that could potentially prevent economic losses in the wine industry.

Highlights

Winemaking is a process in which Saccharomyces cerevisiae is the main yeast responsible for the alcoholic fermentation of grape must to produce wine
In FB, grape variety was Carignan, which is the main and characteristic variety in DOQ Priorat, and the wine samples were collected at the end of malolactic fermentation inoculated with an autochthonous strain of Oenococcus oeni, completed inside BAO and BAN and denoted as 0 time point, at the time points of 3, 6, and 9 months of barrel aging from both barrels, and at the 12-month time point from BAN only, as BAO was accidentally used to refill other barrels due to common practices in the cellar
After performing principal coordinate analysis (PCoA) based on Bray–Curtis distance metric, bacterial communities presented a separation between early (9) maturation wine samples across the first principal component for FB (Figure 3A) accompanied by statistical significance (p-value 0.05) for the factor time

Summary

Introduction

Winemaking is a process in which Saccharomyces cerevisiae is the main yeast responsible for the alcoholic fermentation of grape must to produce wine. A wide diversity of yeast and bacterial species from the grape surfaces, the field, or the cellar facilities and equipment might contribute to the final wine quality (Ribéreau-Gayon et al, 2006; Bokulich et al, 2016). These microorganisms can exert a positive or negative influence through all the winemaking process including wine maturation and aging (Renouf et al, 2005; Moreno-Arribas and Carmen Polo, 2008). The wood barrel aging is a common practice in winemaking for wine maturation of higher red quality wine (Ortega-Heras et al, 2007). Bottle aging is susceptible to undesirable microbial growth even though fining or racking (filtration and clarification) are applied with the aim of microbiological stabilization (Du Toit et al, 2005; Renouf et al, 2005)

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Discussion

Conclusion