A rapid growth rate underpins the dominance of Hanseniaspora uvarum in spontaneous grape juice fermentations

Hanseniaspora uvarum is consistently observed as the dominant non-Saccharomyces species in spontaneous grape juice fermentations. However, the physiological mechanisms and physicochemical variables influencing the prevalence of H. uvarum over other non-Saccharomyces species remain unclear. We tested the physicochemical parameters contributing to H. uvarum dominance by inoculating a chemically diverse set of grape juices with a mock community whose composition was defined following a comprehensive microbial survey of spontaneous fermentations. Our findings indicated that the chemical composition of grape juice had minimal impact on the microbial dynamics of fermentation, with H. uvarum emerging as the dominant non-Saccharomyces species in nearly all conditions tested. Grape juice composition primarily influenced the total yeast abundance of the mock community. Flow cytometry analysis confirmed that H. uvarum has a faster growth rate than Saccharomyces cerevisiae and several other Hanseniaspora spp.. Moreover, its growth was not affected by the presence of S. cerevisiae, explaining its rapid dominance in spontaneous fermentations. The rapid growth of H. uvarum negatively impacted the growth of S. cerevisiae, with significant implications for fermentation performance and sugar consumption. The results of this study suggest that the fast growth rate of H. uvarum enables it to quickly dominate the grape juice environment during the early stages of fermentation. This physiological advantage indicates that the initial abundance of H. uvarum may be critical to the outcome of spontaneous fermentations, as evidenced by its direct impact on the growth of S. cerevisiae and fermentation performance.