Project description:Adaptive laboratory evolution is highly effective for improving desired traits through natural selection. However, its applicability is inherently constrained to growth-correlated traits precluding traits of interest that incur a fitness cost, such as metabolite secretion. Here, we introduce the concept of tacking trait enabling natural selection of fitness-costly metabolic traits. The concept is inspired from the tacking maneuver used in sailing for traversing upwind. We use first-principle metabolic models to design an evolution niche wherein the tacking trait and fitness become correlated. Adaptive evolution in this niche, when followed by the reversal to the original niche, manifests in the improvement of the desired trait due to biochemical coupling between the tacking and the desired trait. We experimentally demonstrated this strategy, termed EvolveX, by evolving wine yeasts for increased aroma production. RNA-sequencing was performed for parental and evolved strains in the respective evolution niche and in natural grape must.
Project description:Adaptive laboratory evolution is highly effective for improving desired traits through natural selection. However, its applicability is inherently constrained to growth-correlated traits precluding traits of interest that incur a fitness cost, such as metabolite secretion. Here, we introduce the concept of tacking trait enabling natural selection of fitness-costly metabolic traits. The concept is inspired from the tacking maneuver used in sailing for traversing upwind. We use first-principle metabolic models to design an evolution niche wherein the tacking trait and fitness become correlated. Adaptive evolution in this niche, when followed by the reversal to the original niche, manifests in the improvement of the desired trait due to biochemical coupling between the tacking and the desired trait. We experimentally demonstrate this strategy, termed EvolveX, by evolving wine yeasts for increased aroma production. Our results pave the way for precision laboratory evolution for biotechnological and ecological applications.
Project description:Fuel ethanol is now considered a global energy commodity that is fully competitive with gasoline. We have determined genome copy number differences that are common to five industrially important fuel ethanol yeast strains responsible for the production of billions of gallons of fuel ethanol per year from sugarcane. The fuel strains used were CAT1, BG1, PE2, SA1, and VR1 (note that two independent isolates were analyzed, denoted by "-1" and "-2"). These array-CGH data were compared with array-CGH data from nine other non-fuel industrial yeasts: An ale brewing strain ("Sc-ale"), four wine strains (GSY2A, GSY3A, GSY10A, GSY11B), and 4 bakers' yeast strains (GSY149, GSY150, GSY154, GSY155). Our results reveal significant amplifications of the telomeric SNO and SNZ genes only in the fuel strains, whose protein products are involved in the biosynthesis of vitamins B6 (pyridoxine) and B1 (thiamin). We show that these amplifications allow these yeasts to grow efficiently, especially at high sugar concentrations, regardless of the presence or absence of either of the two vitamins. Our results reveal important genetic adaptations that have been selected for in the industrial environment, which may be required for the efficient fermentation of biomass-derived sugars from other renewable feedstocks. A strain or line experiment design type assays differences between multiple strains, cultivars, serovars, isolates, lines from organisms of a single species. Strain Name: fuel strains used for aCGH Strain_or_line_design
Project description:The goal of this study was to compare the expression level of the whole genome of two wine yeast strains highly differing in their sulfite production (High producer strain: 10281A; Low producer strain: 1764A). Conditions maximizing SO2 production were selected: nitrogen rich media (425 mg/l assimilable nitrogen) and low temperature (16°C). This transcriptomic analysis was performed during the sulfite production phase, just after the entry in stationary phase. This analysis is part of a global work, aiming at the identification of the molecular basis of sulfite production by wine yeasts through physiologic, transcriptomic and genetic studies.
Project description:Fuel ethanol is now considered a global energy commodity that is fully competitive with gasoline. We have determined genome copy number differences that are common to five industrially important fuel ethanol yeast strains responsible for the production of billions of gallons of fuel ethanol per year from sugarcane. The fuel strains used were CAT1, BG1, PE2, SA1, and VR1 (note that two independent isolates were analyzed, denoted by "-1" and "-2"). These array-CGH data were compared with array-CGH data from nine other non-fuel industrial yeasts: An ale brewing strain ("Sc-ale"), four wine strains (GSY2A, GSY3A, GSY10A, GSY11B), and 4 bakers' yeast strains (GSY149, GSY150, GSY154, GSY155). Our results reveal significant amplifications of the telomeric SNO and SNZ genes only in the fuel strains, whose protein products are involved in the biosynthesis of vitamins B6 (pyridoxine) and B1 (thiamin). We show that these amplifications allow these yeasts to grow efficiently, especially at high sugar concentrations, regardless of the presence or absence of either of the two vitamins. Our results reveal important genetic adaptations that have been selected for in the industrial environment, which may be required for the efficient fermentation of biomass-derived sugars from other renewable feedstocks. A strain or line experiment design type assays differences between multiple strains, cultivars, serovars, isolates, lines from organisms of a single species. Strain Name: fuel strains used for aCGH
2009-09-24 | GSE13875 | GEO
Project description:Wine yeasts of different samples
Project description:The yeast Dekkera bruxellensis is as ethanol tolerant as Saccharomyces cerevisiae and may be found in bottled wine. It causes the spoilage of wine, beer, cider and soft drinks. In wines, the metabolic products responsible for spoilage by Dekkera bruxellensis are mainly volatile phenols. These chemical compounds are responsible for the taints described as ‘‘medicinal’’ in white wines (due to vinyl phenols) and as ‘‘leather’’, ‘‘horse sweat’’ and ‘‘stable’’ in red wines (due to ethyl phenols mainly 4-ethylphenol). Apart from the negative aroma nuances imparted by these yeasts, positive aromas such as ‘smoky’, ‘spicy’ and ‘toffee’ are also cited. Our goal was to identify the impact that the wine spoilage yeast Dekkera bruxellensis has on fermenting S. cerevisiae cells, especially on its gene expression level. To this end we co-inoculated both yeast species at the start of fermentation in a synthetic wine must, using S. cerevisiae-only fermentations without Dekkera bruxellensis as a control. All fermentations were employed in special membrane reactors (1.2 um pore size cut-off) physically separating Dekkera bruxellensis from wine yeast S. cerevisiae. Biomass separation with this membrane was done to abolish the possibility of hybridizing also D. bruxellensis probes on Agilent V2 (8x15K format) G4813 DNA microarrays designed just for S. cerevisiae ORF targets. The 1.2 um pore membrane separating both yeasts allowed the exchange of ethanol, metabolites and sugars during the fermentation.