Proteomic characterisation of wine yeast\nstrains for the expression of arginases\ninvolved in urea formation during\nfermentation
Bibliographic record
Abstract
Wine is a fermented beverage widely consumed all over the world as a recreational drink, but is known for its health benefits to humans.However, wine contain urea, a by-product of arginine hydrolysis by arginases expressed during fermentation by the wine yeast Saccharomyces cerevisiae, which reacts spontaneously with ethanol to form ethyl carbamate (EC).Ethyl carbamate was implicated in toxicity and carcinogenicity.Subsequently, small scale (18 L) Sauvignon Blanc and Cabernet Sauvignon winemaking trials using commercial wine yeasts were initialised during the 2014 and 2015 vintages to measure urea in final wines.The overall aim of this study was to investigate wine yeast protein expression during alcoholic fermentation and establish a possible correlation between urea formation by wine yeast and up/down regulated yeast proteins.Ion-exchange chromatography in conjunction with spectrophotometry was used to measure urea levels in bottled wines.The yeast strain, Prise de Mousse (PdM) was shown to be the lowest urea producer in both Sauvignon Blanc and Cabernet Sauvignon wines.The highest urea producing yeast strain i.e.UCD522 produced Cabernet Sauvignon and Sauvignon Blanc wines with urea exceeding 2 mg/L.Therefore, urea levels in these wines are above the Canadian legal limit, but comply with the USA voluntary limit (5 mg/L).Chemical analyses showed that all wines fermented to dryness and the sensory evaluations showed that none of the wines were negatively perceived by the judges.Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed differential protein expression for the various yeast strains.Proteins of interest were, therefore, excised and characterised using matrixassisted laser desorption ionisation time of flight mass spectrometry (MALDI-TOF/MS).Characterisation of the proteins released from seven Saccharomyces yeasts during alcoholic fermentation were performed, by visualizing the protein profile on SDS-PAGE and identifying the differential expressed proteins in the fermentations with MALDI-TOF.It was observed that the yeast EC1118 that produced Sauvignon Blanc and Cabernet Sauvignon wines with a positive association with volatile acidity (VA), upregulated the protein HSC82 associated with stress response.Therefore, this observation compliments previous research, since VA is known to be produced by wine yeast in response to stressful environments.It is also noteworthy, that the high urea producing reference UCD522 that produced Sauvignon Blanc wines with a negative association with VA also expressed the HSC82 stress response http://etd.uwc.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".