Yeast Biodiversity from DOQ Priorat Uninoculated Fermentations

Area of Science:

• Oenology and Viticulture
• Microbiology
• Environmental Science

Background:

• Terroir, encompassing climate, soil, and grape variety, defines wine origin appellations.
• Grape microbiota, influenced by terroir, contributes a microbial footprint to wine characteristics.
• Understanding vineyard yeast populations is crucial for winemaking and tracing microbial origins.

Purpose of the Study:

• To characterize the yeast microbiota associated with Grenache and Carignan grapes from the DOQ Priorat region.
• To analyze yeast population dynamics during spontaneous alcoholic fermentation at a laboratory scale.
• To correlate vineyard yeast diversity with potential contributions to wine terroir.

Main Methods:

• Sampling of Grenache and Carignan grapes from four distinct DOQ Priorat vineyards.
• Conducting eight small-scale spontaneous alcoholic fermentations using single-variety, single-origin grape must.
• Yeast identification via RFLP-PCR of the 5.8S-ITS region and D1/D2 26S rRNA gene sequencing.
• Monitoring fermentation kinetics and yeast population dynamics throughout the process.

Main Results:

• Fermentation kinetics showed no significant differences between grape varieties or vineyards.
• Approximately 1,400 yeast isolates were identified, revealing high species richness in some fermentations.
• Dominant genera included Hanseniaspora (approx. 60%), Saccharomyces (16%), and Candida (11%).
• Saccharomyces cerevisiae predominantly appeared late in fermentation, while Aureobasidium pullulans was found early in some fermentations.

Conclusions:

• The vineyard ecosystem exhibits significant yeast diversity, with various species contributing to fermentation.
• Identifying native microbiota can aid in selecting yeast strains for producing high-quality wines that express Priorat's unique terroir.
• This research underscores the importance of vineyard-specific yeast populations in shaping wine characteristics.