Project description:Investigation of whole genome gene expression level changes in three S. cerevisiae Y55 mutants, compared to the wild-type strain. The UV-induced mutations enable the mutant strains to ferment high-gravity maltose faster than the WT. The mutants analyzed in this study are further described in Baerends, R.J.S., J.L. Qiu, L. Gautier, and A. Brandt. A high-throughput system for screening of fast-fermenting Saccharomyces cerevisiae strains. Manuscript in preparation. A single-dye 12-plex array chip study using double-stranded DNA prepared from messenger RNA purified from total RNA recovered from three separate Saccharomyces cerevisiae Y55 wild-type cultures and 3x three separate cultures each corresponding to a fast-fermenting UV-induced mutant (mutant 1, 2 and 3), during fermentation of high-gravity maltose at day 2. Each array on the 12-plex chip measures the expression level of 5,777 genes from Saccharomyces cerevisiae S288C with eight 60-mer probes per gene, with three-fold technical redundancy.
Project description:The implementation of a cost-effective lignocellulosic ethanol production requires developing efficient high gravity processes (i.e. working at high substrate concentrations). During the fermentation processes, the presence of high concentration of insoluble solids leads to lower glucose consumption rates, reduced ethanol volumetric productivities, and the accumulation of intracellular reactive oxygen species (ROS). Major repressed biological processes include cell cycle progression, trehalose and glycogen biosynthesis, DNA repair mechanisms, and certain genes involved in the general cell stress response. On the other hand, genes related to the glutathione, thioredoxin and methionine scavenging systems are induced.
Project description:To further study the transcription profile of mutant M1 and its control (BY-P41K-RPB7), we have employed whole genome microarray expression profiling as a discovery platform to identify differentially expressed genes in YPAD medium under OD600 reached 1 and after 12 VHG fermentation.
Project description:To further study the transcription profile of mutant M1 and its control (BY-P41K-RPB7), we have employed whole genome microarray expression profiling as a discovery platform to identify differentially expressed genes in YPAD medium under OD600 reached 1 and after 12 VHG fermentation. Total cellular RNAs were extracted from both the mutant and the control using RNeasy® Mini Kit and RNase-Free DNase Set (Qiagen,Hilden, Germany) under the following two conditions: i) when cells reached early exponential phase (OD600 ~1.0) in YPAD; ii) after 12h VHG fermentation. RNA quality and integrity was verified by gel electrophoresis, as well as by measuring 260/230 ratios with a NanoDrop 1000 spectrophotometer (Thermo Scientific, MA, USA). Two biological replicates of each sample were sent to Genomax Technologies (Singapore) for DNA microarray assay using Yeast (V2) Gene Expression Microarray, 8�15K Microarrays (Agilent technologies, USA). The obtained data was analyzed by Agilent Genespring GX software and the p-values were calculated by unpaired Student t-test.
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:During fermentation Saccharomyces yeast produces various aroma-active metabolites determining the different characteristics of aroma and taste in fermented beverages. Amino acid utilization by yeast during brewer´s wort fermentation is seen as linked to flavour profile. To better understand the relationship between the biosynthesis of aroma relevant metabolites and the importance of amino acids, DNA microarrays were performed for Saccharomyces cerevisiae strain S81 and Saccharomyces pastorianus var. carlsbergensis strain S23, respectively. Thereby, changes in transcription of genes were measured, which are associated with amino acid assimilation and its derived aroma-active compounds during fermentation.
Project description:Investigation of whole genome gene expression level changes in three S. cerevisiae Y55 mutants, compared to the wild-type strain. The UV-induced mutations enable the mutant strains to ferment high-gravity maltose faster than the WT. The mutants analyzed in this study are further described in Baerends, R.J.S., J.L. Qiu, L. Gautier, and A. Brandt. A high-throughput system for screening of fast-fermenting Saccharomyces cerevisiae strains. Manuscript in preparation.
Project description:The main objective was to identify genes regulated during different stages of fermentation: bottom of the fermentor, feeding and the fermentation stage. The experiment was further validated by microbiological assays.
Project description:The main objective was to identify genes regulated during different stages of fermentation: bottom of the fermentor, feeding and the fermentation stage. The experiment was further validated by microbiological assays.