Enzyme Secreting Yeast


Project Number
IWBT-Y 08-05

Project title
Enzyme secreting yeast

Project leader
Divol, B

Institution
University of Stellenbosch. Faculty of AgriSciences. Institute for Wine Biotechnology

Team members
Bauer, F F
Divol, B
Van Rensburg, P
Van Wyk, H

Project description
The secretion of enzymes of enological interest by wine yeast is usually poor under winemaking conditions. For this reason, the addition of enzymes by wine makers during alcoholic fermentation has become a common practice. These enzymes are of different nature, but mostly combine enzymes breaking the network of grape cell walls in order to release more aromas and eventually to facilitate filtration and other clarification practices.

This project deals with the improvement of enzymes secretion by wine yeasts during alcoholic fermentation in order to decrease or suppress the addition of commercial enzymes.

Two main projects are included in this main project.
1. Recovery of endo-polygalacturonase activity in wine strains of Saccharomyces cerevisiae devoid in this enzymatic activity. Many strains of Saccharomyces cerevisiae, especially wine strains, are devoid in pectinase activity. For few strains, this absence is due to the natural loss of a gene. This project aims to reintroduce this gene in these particular strains while keeping their strong enological properties.
2. Secretion of ß-glucosidase by wine strains of Saccharomyces cerevisiae. It has been noticed that the secretion of ß-glucosidase enzymes by Saccharomyces cerevisiae during alcoholic fermentation is not sufficient and/or not effective enough under winemaking conditions. We propose here to clone and express the ß-glucosidase-encoding gene of Debaryomyces pseudopolymorphus which has recently been described as more effective in a wine strain of Saccharomyces cerevisiae.

Poster(s)
Van Wyk, H and Divol, B. 2008. Recovery of endo-polygalacturonase activity in wine yeast strains and its effect on wine aroma. Poster presented at the 31st National Congress of the South African Society for Enology and Viticulture. 11-14 November, Somerset West, South Africa.

Presentation(s)
Van Wyk, H and Divol, B. 2008. Recovery of endo-polygalacturonase activity in recombinant wine strains of Saccharomyces cerevisiae. Paper presented at the International Symposium Food Micro 2008. 1-4 September 2008, Aberdeen, Scotland, United Kingdom.

Eschsteuth, A and Divol, B. 2010. Altering wine bouquet by overexpressing non-Saccharomyces yeasts ß-glucosidases. Paper presented at Genetics of Industrial Micro-organisms. Melbourne, Australia.

Eschstruth, A and Divol, B. 2011. Expression of Saccharomyces cerevisiae and Saccharomyces paradoxus endo-polygalacturonase-encoding genes enhances juice extraction without much alteration of wine composition. Paper presented at the 9th International Enology Symposium: OENO 2011. 15-17 June, Bordeaux, France.

Article
Van Wyk, H, Divol, G. 2010. Recovery of endo-polygalacturonase activity in wine yeast and its effect on wine aroma, FEMS Yeast Research, Mnth Feb v. 10 (1) (p. 58-71)

Van Wyk, H, Divol, B. 2010. Recovery of endo-polygalacturonase activity in wine yeast and its effect on wine aroma, FEMS Yeast Research, v. 10 (p. 58-71)
http://dx.doi.org/10.1111/j.1567-1364.2009.00588.x

Eschstruth, A, Divol, B. 2011. Comparative characterization of endo-polygalacturonase (Pgu1) from Saccharomyces cerevisiae and Saccharomyces paradoxus under winemaking conditions, Applied Microbiology and Biotechnology, v. 91 (p. 623-634)

Thesis
Van Wyk, H. 2009. Analysis of endo-polygalacturonase activity in recombinant yeast containing a reconstituted PGU1 gene. MScAgric (Grapevine and Wine Biotechnology) University of Stellenbosch, Stellenbosch, South Africa.

FinalReport.pdf

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