The use of sulfur dioxide as an antimicrobial in winemaking is a well-established, common practice. While much is known about its antimicrobial effects at single doses, little is known about its effects on microbial dynamics across a range of doses in conjunction with yeast inoculation. We investigated the cumulative impacts of yeast inoculation and sulfur dioxide treatments across a broad dose range (0–150 μg/L SO2) on the bacterial and fungal communities of wine fermentations using high-throughput marker-gene sequencing. Results reveal a dose-dependent effect, with lactic acid bacteria and Gluconobacter proliferating in fermentations receiving < 25 μg/L SO2, but other bacteria and fungi were unaffected by treatment. Microbial profiles were stabilized at doses ≥25 μg/L SO2, and fermentation performance decreased at higher doses (100–150 μg/L SO2). Yeast inoculation alone conferred a stabilizing effect, reducing the bacterial growth seen in unsulfited fermentations, but this effect was not additive in conjunction with SO2 additions.
- ©2014 by the American Society for Enology and Viticulture