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Applied and Environmental Microbiology, October 2008, p. 6041-6052, Vol. 74, No. 19
0099-2240/08/$08.00+0     doi:10.1128/AEM.00394-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Controlled Expression of the Dominant Flocculation Genes FLO1, FLO5, and FLO11 in Saccharomyces cerevisiae{triangledown}

Patrick Govender,1,2 Jody L. Domingo,2 Michael C. Bester,2 Isak S. Pretorius,3 and Florian F. Bauer2*

Department of Biochemistry, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa,1 Institute for Wine Biotechnology, Faculty of AgriSciences, University of Stellenbosch, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa,2 The Australian Wine Research Institute, P.O. Box 197, Glen Osmond (Adelaide), South Australia 5064, Australia3

Received 16 February 2008/ Accepted 5 August 2008

In many industrial fermentation processes, the Saccharomyces cerevisiae yeast should ideally meet two partially conflicting demands. During fermentation, a high suspended yeast count is required to maintain a satisfactory rate of fermentation, while at completion, efficient settling is desired to enhance product clarification and recovery. In most fermentation industries, currently used starter cultures do not satisfy this ideal, probably because nonflocculent yeast strains were selected to avoid fermentation problems. In this paper, we assess molecular strategies to optimize the flocculation behavior of S. cerevisiae. For this purpose, the chromosomal copies of three dominant flocculation genes, FLO1, FLO5, and FLO11, of the haploid nonflocculent, noninvasive, and non-flor-forming S. cerevisiae FY23 strain were placed under the transcriptional control of the promoters of the ADH2 and HSP30 genes. All six promoter-gene combinations resulted in specific flocculation behaviors in terms of timing and intensity. The strategy resulted in stable expression patterns providing a platform for the direct comparison and assessment of the specific impact of the expression of individual dominant FLO genes with regard to cell wall characteristics, such as hydrophobicity, biofilm formation, and substrate adhesion properties. The data also clearly demonstrate that the flocculation behavior of yeast strains can be tightly controlled and fine-tuned to satisfy specific industrial requirements.

* Corresponding author. Mailing address: Institute for Wine Biotechnology, Faculty of AgriSciences, University of Stellenbosch, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa. Phone: 27 21 808 4346. Fax: 27 21 808 3771. E-mail: fb2{at}sun.ac.za

{triangledown} Published ahead of print on 15 August 2008.

Applied and Environmental Microbiology, October 2008, p. 6041-6052, Vol. 74, No. 19
0099-2240/08/$08.00+0     doi:10.1128/AEM.00394-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Rossouw, D., Olivares-Hernandes, R., Nielsen, J., Bauer, F. F. (2009). Comparative Transcriptomic Approach To Investigate Differences in Wine Yeast Physiology and Metabolism during Fermentation. Appl. Environ. Microbiol. 75: 6600-6612 [Abstract] [Full Text]  


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