Comparative 'omic' profiling of industrial wine yeast strains

[摘要] The main goal of this project was to elucidate the underlying genetic factors responsible for thedifferent fermentation phenotypes and physiological adaptations of industrial wine yeast strains. Toaddress this problem an 'omic' approach was pursued: Five industrial wine yeast strains, namelyVIN13, EC1118, BM45, 285 and DV10, were subjected to transcriptional, proteomic and exometabolomicprofiling during alcoholic fermentation in simulated wine-making conditions. The aimwas to evaluate and integrate the various layers of data in order to obtain a clearer picture of thegenetic regulation and metabolism of wine yeast strains under anaerobic fermentative conditions.The five strains were also characterized in terms of their adhesion/flocculation phenotypes,tolerance to various stresses and survival under conditions of nutrient starvation.Transcriptional profiles for the entire yeast genome were obtained for three crucial stages duringfermentation, namely the exponential growth phase (day 2), early stationary phase (day 5) and latestationary phase (day 14). Analysis of changes in gene expression profiles during the course offermentation provided valuable insights into the genetic changes that occur as the yeast adapt tochanging conditions during fermentation. Comparison of differentially expressed transcriptsbetween strains also enabled the identification of genetic factors responsible for differences in themetabolism of these strains, and paved the way for genetic engineering of strains with directedmodifications in key areas. In particular, the integration of exo-metabolite profiles and geneexpression data for the strains enabled the construction of statistical models with a strong predictivecapability which was validated experimentally.Proteomic analysis enabled correlations to be made between relative transcript abundance andprotein levels for approximately 450 gene and protein pairs per analysis. The alignment oftranscriptome and proteome data was very accurate for interstrain comparisons. For intrastraincomparisons, there was almost no correlation between trends in protein and transcript levels, exceptin certain functional categories such as metabolism. The data also provide interesting insights intomolecular evolutionary mechanisms that underlie the phenotypic diversity of wine yeast strains.Overall, the systems biology approach to the study of yeast metabolism during alcoholicfermentation opened up new avenues for hypothesis-driven research and targeted engineeringstrategies for the genetic enhancement/ modification of wine yeast for commercial applications.

[发布机构] Stellenbosch University