Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/97444
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Type: Journal article
Title: Genome-wide identification of the Fermentome; genes required for successful and timely completion of wine-like fermentation by Saccharomyces cerevisiae
Author: Walker, M.
Nguyen, T.
Liccioli, T.
Schmid, F.
Kalatzis, N.
Sundstrom, J.
Gardner, J.
Jiranek, V.
Citation: BMC Genomics, 2014; 15(1):552-1-552-17
Publisher: BioMed Central
Issue Date: 2014
ISSN: 1471-2164
1471-2164
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Michelle E Walker, Trung D Nguyen, Tommaso Liccioli, Frank Schmid, Nicholas Kalatzis, Joanna F Sundstrom, Jennifer M Gardner and Vladimir Jiranek
Abstract: BACKGROUND: Wine fermentation is a harsh ecological niche to which wine yeast are well adapted. The initial high osmotic pressure and acidity of grape juice is followed by nutrient depletion and increasing concentrations of ethanol as the fermentation progresses. Yeast's adaptation to these and many other environmental stresses, enables successful completion of high-sugar fermentations. Earlier transcriptomic and growth studies have tentatively identified genes important for high-sugar fermentation. Whilst useful, such studies did not consider extended growth (>5 days) in a temporally dynamic multi-stressor environment such as that found in many industrial fermentation processes. Here, we identify genes whose deletion has minimal or no effect on growth, but results in failure to achieve timely completion of the fermentation of a chemically defined grape juice with 200 g L-1 total sugar. RESULTS: Micro- and laboratory-scale experimental fermentations were conducted to identify 72 clones from ~5,100 homozygous diploid single-gene yeast deletants, which exhibited protracted fermentation in a high-sugar medium. Another 21 clones (related by gene function, but initially eliminated from the screen because of possible growth defects) were also included. Clustering and numerical enrichment of genes annotated to specific Gene Ontology (GO) terms highlighted the vacuole's role in ion homeostasis and pH regulation, through vacuole acidification. CONCLUSION: We have identified 93 genes whose deletion resulted in the duration of fermentation being at least 20% longer than the wild type. An extreme phenotype, 'stuck' fermentation, was also observed when DOA4, NPT1, PLC1, PTK2, SIN3, SSQ1, TPS1, TPS2 or ZAP1 were deleted. These 93 Fermentation Essential Genes (FEG) are required to complete an extended high-sugar (wine-like) fermentation. Their importance is highlighted in our Fermentation Relevant Yeast Genes (FRYG) database, generated from literature and the fermentation-relevant phenotypic characteristics of null mutants described in the Saccharomyces Genome Database. The 93-gene set is collectively referred to as the 'Fermentome'. The fact that 10 genes highlighted in this study have not previously been linked to fermentation-related stresses, supports our experimental rationale. These findings, together with investigations of the genetic diversity of industrial strains, are crucial for understanding the mechanisms behind yeast's response and adaptation to stresses imposed during high-sugar fermentations.
Keywords: Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Genetic Engineering; Gene Deletion; Fermentation; Genes, Fungal; Hydrogen-Ion Concentration; Wine; Transcriptome
Rights: © 2014 Walker et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
RMID: 0030010217
DOI: 10.1186/1471-2164-15-552
Appears in Collections:Agriculture, Food and Wine publications

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