Controlled expression of the dominant flocculation genes FLO1, FLO5, and FLO11 in Saccharomyces cerevisiae
Date
2008
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Abstract
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. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Description
Keywords
Biochemical engineering, Cell culture, Clarification, Enhanced recovery, Flocculation, Forming, Genes, Strain, Yeast, And recoveries, Biofilm formations, Cell walls, Efficient, Gene combinations, Industrial fermentations, Industrial requirements, Molecular strategies, Noninvasive, S. cerevisiae, Saccharomyces cerevisiae, Stable expressions, Starter cultures, Substrate adhesions, Transcriptional controls, Yeast strains, Fermentation, heat shock protein 30, ADH2 protein, S cerevisiae, alcohol dehydrogenase, FLO1 protein, S cerevisiae, FLO5 protein, S cerevisiae, glucose, HSP30 protein, S cerevisiae, mannose, membrane protein, MUC1 protein, S cerevisiae, Saccharomyces cerevisiae protein, biofilm, fermentation, flocculation, food industry, gene expression, hydrophobicity, optimization, yeast, article, bacterial gene, controlled study, flo1 gene, FLO11 gene, flo5 gene, flocculation, gene expression, gene sequence, hydrophobicity, nonhuman, Saccharomyces cerevisiae, biofilm, biosynthesis, cell wall, chemistry, gene expression regulation, genetics, growth, development and aging, metabolism, methodology, microbiology, physiology, promoter region, Saccharomyces cerevisiae, Alcohol Dehydrogenase, Biofilms, Cell Wall, Flocculation, Gene Expression Regulation, Fungal, Glucose, HSP30 Heat-Shock Proteins, Hydrophobicity, Industrial Microbiology, Mannose, Membrane Proteins, Promoter Regions (Genetics), Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Citation
Applied and Environmental Microbiology
74
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74
19