Project description:High concenHigh concentration acetic acid in the fermentation medium represses cell growth, metabolism and fermentation efficiency of Saccharomyces cerevisiae, which is widely used for cellulosic ethanol production. Our previous study proved that supplementation of zinc sulfate in the fermentation medium improved cell growth and ethanol fermentation performance of S. cerevisiae under acetic acid stress condition. However, the molecular mechanisms is still unclear. To explore the underlying mechanism of zinc sulfate protection against acetic acid stress, transcriptomic and proteomic analysis were performed. The changed genes and proteins are related to carbon metabolism, amino acid biosynthesis, energy metabolism, vitamin biosynthesis and stress responses. In a total, 28 genes showed same expression in transcriptomic and proteomic data, indicating that zinc sulfate affects gene expression at posttranscriptional and posttranslational levels.tration acetic acid in the fermentation medium represses cell growth, metabolism and fermentation efficiency of Saccharomyces cerevisiae, which is widely used for cellulosic ethanol production. Our previous study proved that supplementation of zinc sulfate in the fermentation medium improved cell growth and ethanol fermentation performance of S. cerevisiae under acetic acid stress condition. However, the molecular mechanisms is still unclear. To explore the underlying mechanism of zinc sulfate protection against acetic acid stress, transcriptomic and proteomic analysis were performed. The changed genes and proteins are related to carbon metabolism, amino acid biosynthesis, energy metabolism, vitamin biosynthesis and stress responses. In a total, 28 genes showed same expression in transcriptomic and proteomic data, indicating that zinc sulfate affects gene expression at posttranscriptional and posttranslational levels.
Project description:The present work aimed to compare the transcriptome of three major ethanol-producer Saccharomyces cerevisiae strains in Brazil when fermenting sugarcane juice for fuel ethanol production. This was motivated by the reports presenting physiological and genomics differences among them, and by the attempt to identify genes that could be related to their fermentation capacity and adaptation for different industrial processes.
Project description:We used genome-wide expression analyses to study the response of Saccharomyces cerevisiae to stress throughout a 15-day wine fermentation. Forty percent of the yeast genome significantly changed expression levels to mediate long-term adaptation to an environment in which ethanol is both a stressor and a carbon source. Within this set, we identify a group of 223 genes, designated as the Fermentation Stress Response (FSR), that are dramatically and permanently induced; FSR genes exhibited changes ranging from four-to eighty-fold. The FSR is novel; 62% of the genes involved have not been implicated in global stress responses and 28% of the genes have no functional annotation. Genes involved in respiratory metabolism and gluconeogenesis were expressed during fermentation despite the presence of high concentrations of glucose. Ethanol, rather than nutrient depletion, was responsible for entry of yeast cells into stationary phase. Ethanol seems to regulate yeast metabolism through hitherto undiscovered regulatory networks during wine fermentation. Keywords: time course, stress response, fermentation
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:The environmental stresses and inhibitors encounted by Saccharomyces cerevisiae strains are main limiting factors in bioethanol fermentation. Investigation of the molecular mechanisms underlying the stresses-related phenotypes diversities within and between S. cerevisiae populations could guide the construction of yeast strains with improved stresses tolerance and fermentation performances. Here, we explored the genetic characteristics of the bioethanol S. cerevisiae strains, and elucidated the genetic variations correlated with its advantaged traits (higher ethanol yield under sever conditions and better tolerance to multiple stresses compared to an S288c derived laboratory strain BYZ1). Firstly, pulse-field gel electrophoresis combined with array-comparative genomic hybridization was used to compare the genome structure of industrial strains and the laboratory strain BYZ1.
Project description:Populations of engineered metabolite-producing microorganisms are prone to evolutionary production declines during industrial-scale cultivations. In this study, we develop a synthetic product addiction system in E coli that addicts mevalonic acid production cells to mevalonic acid. Through experimentally simuluated long-term fermentation, we investigate how product-addicted organisms remain stable and avoid formation of genetic subpopulations of fit, non-producing cells.
Project description:Ethanol-stressed conditions were applied to ε-polylysine fermentation to study the changes in protein levels of Streptomyces albicans under ethanol-stimulated conditions
Project description:we aimed to screen candidate kinase genes under the stress of phenolic aldehydes during ethanol fermentation for Zymomonas mobilis ZM4