Microbial terroir of Helan Mountain east foothill: The role of indigenous yeasts in shaping regional wine flavor during spontaneous fermentation

Indigenous microbial communities are essential in shaping regional wine flavor during spontaneous fermentation. In this study, spontaneously fermented Cabernet Sauvignon and Marselan wines were collected from seven sub-regions in the eastern foothills of the Helan Mountains, Ningxia. We analyzed the succession patterns of yeasts and their associations with flavor compounds to reveal how microbial dynamics drive flavor development. A total of 29 yeast species from 19 genera were isolated. Saccharomyces cerevisiae , Hanseniaspora uvarum , and Starmerella bacillaris dominated the early stage of fermentation. Yeast community structures showed significant temporal and regional variation. 9 organic acids and 24 monomeric phenols were identified by high-performance liquid chromatography–mass spectrometry (HPLC–MS). 26 core volatile compounds were characterized through headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) and odor activity value (OAV) analysis. Sensory analysis confirmed that each region exhibited distinct aroma markers. Correlation analysis demonstrated strong associations between specific yeast species and physicochemical parameters, phenolic compositions, and volatile compounds. For example, Saccharomyces cerevisiae correlated positively with alcohol and volatile acids, and negatively with residual sugar and total acidity. Specific non- Saccharomyces yeasts may contribute significantly to regional wine character. This study provides a theoretical foundation for understanding indigenous yeasts' roles in regional wine flavor differentiation.