Culture-independent and culture-dependent methods were used to determine the persistence of Hanseniaspora uvarum, Candida sp. EJ1, and Saccharomyces cerevisiae populations within wine fermentations treated with inhibitory levels of sulfur dioxide. Upon addition, SO2 completely inhibited growth of Hanseniaspora and Candida populations on enrichment media; however, PCR and RT-PCR signatures of each species persisted, in some cases, throughout the complete fermentation (as long as 20 days). PCR-DGGE and RT-PCR-DGGE profiles of yeasts present in the fermentations also indicated persistence of Hanseniaspora and Candida populations after their respective plating populations disappeared. This study demonstrates that molecular signatures of non-Saccharomyces yeasts can remain in wine fermentations treated with SO2 long after those populations become nonculturable.
Acknowledgments: The authors gratefully acknowledge the financial support of the American Vineyard Foundation, the California Competitive Grants Program for Research in Viticulture and Enology. The authors thank David Block for assistance with the HPLC analysis and Trevor Phister for initial review of the manuscript.
- Copyright 2003 by the American Society for Enology and Viticulture