Increasing the robustness of wine yeasts
Background
Without doubt, Australian wine producers will benefit from improvements in the performance and consistency of commercial fermentations. Despite an increased understanding of the nutritional requirements of yeast and an improved understanding of the composition of must, fermentation performance continues to be a cause for concern for producers, with requests for literature on stuck and sluggish fermentations constituting one of the AWRI Information Services’ top five enquiries.
Progress
Yeast stress, due to changing conditions in grape must during vinification, is likely to be one of the main contributors to poor fermentation performance. Of the many factors that cause this stress, ethanol accumulation is thought to be one of the most important; for example, increased ethanol concentration has a drastic impact on sugar utilisation in wine yeast.
The contribution of stress tolerance in general, and ethanol tolerance in particular, to fermentation performance is being investigated through a program of strain improvement which aims to generate more robust wine yeasts via the selection of wine yeast isolates with increased stress tolerance.
In a collaborative project between the AWRI, Grant Stanley (Victoria University) and Miguel de Barros-Lopes (University of South Australia) we are also attempting to understand the genetic basis of ethanol tolerance by comparing evolved ethanol-tolerant laboratory strains to parental strains.
Project leader: Dr Paul Chambers
Project team members:
Publications:
Chambers P.J., Bellon J.R., Schmidt S.A., Varela C. and Pretorius I.S. (2007) Non-Genetic engineering approaches to isolating and generating novel yeasts for industrial application. In Diversity and Potential Biotechnological Applications of Yeasts 2008 Ed. Satyanarayana, T., Kunze G. Springer-Verlag, Berlin–Heidelberg–New York, in press.
994 Bartowsky, E., Bellon, J., Borneman, A., Chambers, P., Cordente, A. Costello, P., Curtin, C., Forgan, A., Henschke, P., Kutyna, D., McCarthy, J., Macintyre, O., Schmidt, S., Tran, T., Swiegers, H., Ugliano, M., Varela, C., Willmott, R., Pretorius, S. (2007) Not all wine yeasts are equal. Microbiology Australia 28(2):55-58 (click here to order).
952 Schmidt, S.A., Tran, T., Chambers, P.J., Herderich, M.J., Pretorius, I.S. (2006) Developing indicators of wine yeast performance: the impact of ethanol stress. Aust. N.Z. Wine Ind. J. 21(5):24-30 (click here to order).