Studies of Saccharomyces cerevisiae and Non-Saccharomyces Yeasts during Alcoholic Fermentation: Nitrogen Source Preferences and Mechanisms of Interactions
Research output: Book/Report › Ph.D. thesis › Research
The early death of non-Saccharomyces yeasts during mixed culture spontaneous wine fermentation has traditionally been attributed to the lower capacity of these yeast species to withstand high levels of ethanol, low pH, and other media properties that are a part of progressing fermentation. However, other yeast-yeast interactions, such as cell-cell contact mediated growth arrest and/or toxininduced death may also be a significant factor in the relative fragility of these non-Saccharomyces yeasts in mixed culture fermentation. In the present work we evaluate the combined roles of cell-cell contact and/or antimicrobial peptides on the early death of Lachancea thermotolerans during mixed culture fermentations with Saccharomyces cerevisiae. Using a specially designed double compartment fermentation system, we established that both cell-to-cell contact and antimicrobial peptides contribute to the early death of L. thermotolerans during mixed-culture alcoholic fermentation with S. cerevisiae. These data may be valuable for development of mixed- and sequential starter cultures for tailoring of wine quality and enhanced flavour profiles. As well, we studied the role of nitrogenous sources in completion of anaerobic alcoholic fermentation. For both S. cerevisiae and non-Saccharomyces yeasts, some 22 different nitrogenous sources were evaluated for effects on growth and fermentation ability during anaerobic alcoholic fermentation. The data revealed that nitrogen preference is a trait that is species-specific; as well, growth enhancement is also dependent upon the type of nitrogen supplementation for each yeast species. This work provides the first detailed analysis of appropriate nitrogen supplementation to improve yeast growth and alcoholic fermentative activity (i.e., glucose consumption and ethanol production) of Saccharomyces cerevisiae, Lacchancea thermotolerans, Metschnikowia pulcherrima, Hanseniaspora uvarum and Torulaspora delbrueckii. Given the ability of these non- Saccharomyces yeasts to enhance the wine flavour profile, improvement of culture conditions is of great potential value to the wine-making community. It is also possible that the double compartment fermentation system designed herein might be fruitfully applied at larger scale to permit co-utilization of non-Saccharomyces and Saccharomyces for enhanced flavour profiles of finished wines.
|Publisher||Department of Food Science, Faculty of Science, University of Copenhagen|
|Number of pages||145|
|Publication status||Published - 2015|