Project description:To better understand how yeast adapt and respond to sequential stressors, an industrial yeast strain, URM 6670 (also known as BT0510), which is highly flocculent, tolerant to ethanol, osmotic and heat shock stresses, was subjected to three different treatments: 1. osmotic stress followed by ethanol stress, 2. oxidative stress followed by ethanol stress, 3. glucose withdrawal followed by ethanol stress. Samples were collected before the first stress (control), after the first stress and after the second stress (ethanol). RNA was extracted and analyzed by RNAseq.
Project description:The modification of the The modification of the tolerance of xylose-fermenting yeast is an urgent issue for improving ethanol production. In this study, multiple genes involving in superoxide dismutase, glutathione biosynthesis, NADPH regeneration and acetic acid degradation were overexpressed using stress-induced promoters, which is selected from the transcriptome data. Stress-induced promoters were used to realize the feedback control of the tolerant genes, which can ultimately improve the tolerance and ethanol production. We reported the stress-induced promoters for overexpressing tolerant genes and increasing yeast tolerance in a feedback manner
Project description:The main objective was to identify genes regulated after the BY4742 yeast cells were exposed to 0.125% for 5 or 10 min. The experiment was further valited by microbiological assays. The control for this experiment that used 0.125% propolis as a treatment have 0.68% ethanol for 5 or 10 min (what corresponds to 60% alcoholic extract for 0.125% propolis). For analysis, the cells were exposed to 0.125% for 5 or 10 min were compared to the control.
Project description:Second fermentation in a bottle supposes such specific conditions that undergo yeasts to a set of stress situations like high ethanol, low nitrogen, low pH or sub-optimal temperature. Also, yeast have to grow until 1 or 2 generations and ferment all sugar available while they resist increasing CO2 pressure produced along with fermentation. Because of this, yeast for second fermentation must be selected depending on different technological criteria such as resistance to ethanol, pressure, high flocculation capacity, and good autolytic and foaming properties. All of these stress factors appear sequentially or simultaneously, and their superposition could amplify their inhibitory effects over yeast growth. Considering all of the above, it has supposed interesting to characterize the adaptive response of commercial yeast strain EC1118 during second-fermentation experiments under oenological/industrial conditions by transcriptomic profiling. We have pointed ethanol as the most relevant environmental condition in the induction of genes involved in respiratory metabolism, oxidative stress, autophagy, vacuolar and peroxisomal function, after comparison between time-course transcriptomic analysis in alcoholic fermentation and transcriptomic profiling in second fermentation. Other examples of parallelism include overexpression of cellular homeostasis and sugar metabolism genes. Finally, this study brings out the role of low-temperature on yeast physiology during second-fermentation.
Project description:In this study, using DNA microarray analysis, we compared the comprehensive expression profiles of two yeast trains, i.e, the previously obtained ethanol-adapted yeast strain and the parental strain as control (FY834), under the ethanol stress condition (YPD medium contained 10% ethanol). As a result, we identified certain genes and functional categories of the genes that are possible involved in growth under the ethanol stress condition.
Project description:Second fermentation in a bottle supposes such specific conditions that undergo yeasts to a set of stress situations like high ethanol, low nitrogen, low pH or sub-optimal temperature. Also, yeast have to grow until 1 or 2 generations and ferment all sugar available while they resist increasing CO2 pressure produced along with fermentation. Because of this, yeast for second fermentation must be selected depending on different technological criteria such as resistance to ethanol, pressure, high flocculation capacity, and good autolytic and foaming properties. All of these stress factors appear sequentially or simultaneously, and their superposition could amplify their inhibitory effects over yeast growth. Considering all of the above, it has supposed interesting to characterize the adaptive response of commercial yeast strain EC1118 during second-fermentation experiments under oenological/industrial conditions by transcriptomic profiling. We have pointed ethanol as the most relevant environmental condition in the induction of genes involved in respiratory metabolism, oxidative stress, autophagy, vacuolar and peroxisomal function, after comparison between time-course transcriptomic analysis in alcoholic fermentation and transcriptomic profiling in second fermentation. Other examples of parallelism include overexpression of cellular homeostasis and sugar metabolism genes. Finally, this study brings out the role of low-temperature on yeast physiology during second-fermentation. S. cerevisiae EC1118 pre-adapted to ethanol cells and sucrose (20 g/L) were added to 20 L of base wine (Cavas Freixenet, Sant Sadurní D’Anoia, Spain). Complete volume was bottled with 350 mL each one. All were sealed and incubated in static conditions at 16ºC for approximately 40 days after tirage. Three samples were taken during the process for transcriptional study of the physiological adaptation of yeast cells to industrial second fermentation conditions. A sample corresponding to exponential-growth phase under unstressed conditions (in YPD at 28ºC) was used as an external reference. Three timepoints from second-fermentation were monitored and three biological replicates from each timepoint were analyzed.