CRISPRi reveals genes modulating yeast growth in lignocellulose hydrolysate
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ABSTRACT:
ORGANISM(S): synthetic construct
PROVIDER: GSE155590 | GEO | 2021/02/15
REPOSITORIES: GEO
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Project description:To reach an economically feasible bioethanol process from lignocellulose, efficient fermentation by yeast of all sugars present in the hydrolysate has to be achieved. However, when exposed to lignocellulosic hydrolysate, Saccharomyces cerevisiae is challenged with a variety of inhibitors that reduce yeast viability, growth and fermentation rate, and in addition damage cellular structures. In order to evaluate the yeast capability to adapt to lignocellulosic hydrolysates and to investigate the yeast molecular response to inhibitors, fed-batch cultivation of an industrial S. cerevisiae strain was performed using either spruce hydrolysate or a sugar medium as feed. The physiological effects of cultivating yeast in spruce hydrolysate was comprehensively studied by assessment of yeast performance in simultaneous saccharification and fermentation (SSF), measurement of furaldehyde reduction activity, assessment of conversion of phenolic compounds and genome wide transcription analysis. The yeast cultivated in spruce hydrolysate developed a rapid adaptive response to lignocellulosic hydrolysate, which significantly improved its fermentation performance in subsequent SSF experiments. Yeast adaptation to hydrolysate was shown to involve induction of NADPH-dependent aldehyde reduction activity and conversion of phenolic compounds during the fed-batch cultivation and these properties were correlated to the expression of several genes encoding oxido-reductase activities, notably AAD4, ADH6, OYE2/3 and YML131w. The other most significant transcriptional changes involved genes involved in transport mechanisms, such as YHK8, FLR1 or ATR1. A large set of genes were found to be associated to transcription factors involved in stress response (Msn2p, Msn4p, Yap1p but also cell growth and division (Gcr4p, Ste12p, Sok2p) that were most likely activated at the post-transcriptional level.
2023-02-21 | GSE218764 | GEO
Project description:CRISPRi reveals genes modulating yeast growth in lignocellulose hydrolysate
| PRJNA650409 | ENA
Project description:The physiology of ethanologenic Escherichia coli grown anaerobically in alkaline-pretreated plant hydrolysates is not well studied. To gain insight into how E. coli responds to such hydrolysates, we studied an E. coli K-12 ethanologen fermenting a hydrolysate prepared from corn stover pre-treated by ammonia fiber expansion. Despite the high sugar content (~6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate, E. coli ceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses throughout the different stages of growth. During the exponential and transition phases of growth, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate media. However, after the majority of amino acids were depleted from the media cells entered stationary phase and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic, lignotoxin and ethanol stress collectively limits growth, sugar utilization rates and ethanol yields in alkaline-pretreated lignocellulosic hydrolysates. 38 samples in total. 24 samples were derived from biological replicate fermentations of alkaline-pretreated cornstover hydrolysate (12 datapoint time-series per fermentation). The remaining samples were obtained from fermentations conducted in defined media (Glucose Minimal Media (GMM, n=7), Synthetic Hydrolysate media (SynH, n=7)).
2012-06-17 | E-GEOD-35049 | biostudies-arrayexpress
Project description:The physiology of ethanologenic Escherichia coli grown anaerobically in alkaline-pretreated plant hydrolysates is not well studied. To gain insight into how E. coli responds to such hydrolysates, we studied an E. coli K-12 ethanologen fermenting a hydrolysate prepared from corn stover pre-treated by ammonia fiber expansion. Despite the high sugar content (~6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate, E. coli ceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses throughout the different stages of growth. During the exponential and transition phases of growth, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate media. However, after the majority of amino acids were depleted from the media cells entered stationary phase and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic, lignotoxin and ethanol stress collectively limits growth, sugar utilization rates and ethanol yields in alkaline-pretreated lignocellulosic hydrolysates.
2012-06-18 | GSE35049 | GEO
Project description:Here, we explored natural variation in stress tolerance and in transcriptomic responses to synthetic hydrolysate, mimicking chemically pretreated plant material, to dissect the physiological effects hydrolysate components. Using six different Saccharomyces cerevisiae strains that together maximized phenotypic and genetic diversity, we explored transcriptomic differences between resistant and sensitive strains. We identified both common and strain-specific responses. Comparing responses of resistant and sensitive strains provided insights about primary cellular targets of hydrolysate toxins, implicating cell wall structure, protein and DNA stability, energy stores and redox balance. Importantly, we uncovered lower expression of thiamine genes while in the presence of toxins, which we argue are most likely an indirect effect that increases sensitivity. We also demonstrate synergistic interactions between the nutrient composition, osmolarity, pH, and classes of hydrolysate toxins. Together, this work provides a platform for further dissecting hydrolysate toxins and strain responses. RNA-seq and transcriptome analysis of six S. cerevisiae natural isolates having different resistant to lignocellulosic hydrolysate. Two biological replicate cell samples (collected on different days) were harvested for RNAseq analysis. Strains were grown in YPD, synthetic hydrolysate without toxins (SynH -HTs), and synthetic hydrolysate with toxins (SynH). Cells were grown for at least three generations to log phase (OD600 ~0.5) and collected by centrifugation.
2016-04-01 | E-GEOD-77505 | biostudies-arrayexpress
Project description:Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5M-bM-^@M-^Qhydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts. E.coli ethanologen strain GLBRCE1 was grown in 4 media, AFEX corn stover hydrolysate (ACSH), synthetic hydrolysate (SynH), synthetic hydrolysate with added lignotoxins (SynH_LT), or synthetic hydrolysate containing acid or amide lignotoxins only (SynH_Acids_Amides). Fermentations were carried out in 3 L bioreactors (Applikon Biotechnology) containing 2.45 L of ACSH or SynH media, and cultures were diluted into ACSH or SynH with initial OD at 0.2, grown anaerobically overnight, and then inoculated into bioreactors to a starting OD600 of 0.2. Two biological replicates (independent cultures) were grown in each medium. RNA samples were obtained at 6 time points, corresponding to early exponential (Exp1), Mid-exponential (Exp2), Late-exponential (Exp3), transitional (Trans), stationary (Stat1) and late stationary (Stat2) growth phases.
2014-07-18 | E-GEOD-58977 | biostudies-arrayexpress
Project description:Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5M-bM-^@M-^Qhydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts. E.coli ethanologen strain GLBRCE1 was grown in 3 media, AFEX corn stover hydrolysate (ACSH), synthetic hydrolysate (SynH) and syntetic hydrolysate with added lignotoxins (SynH_LT). Fermentations were carried out in 3 L bioreactors (Applikon Biotechnology) containing 2.45 L of ACSH or SynH media, and cultures were diluted into ACSH or SynH with initial OD at 0.2, grown anaerobically overnight, and then inoculated into bioreactors to a starting OD600 of 0.2. 3 biological replicates (independent cultures) were grown in each medium. RNA samples were obtained at 4 time points, corresponding to exponential (Exp), transitional (Trans), stationary (Stat1) and late stationary (Stat2) growth phases.
2014-07-18 | E-GEOD-58806 | biostudies-arrayexpress
Project description:Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5M-bM-^@M-^Qhydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts. E.coli ethanologen strain GLBRCE1 was grown in 3 media, AFEX corn stover hydrolysate (ACSH), synthetic hydrolysate (SynH) and syntetic hydrolysate with added lignotoxins (SynH_LT). Fermentations were carried out in 3 L bioreactors (Applikon Biotechnology) containing 2.45 L of ACSH or SynH media, and cultures were diluted into ACSH or SynH with initial OD at 0.2, grown anaerobically overnight, and then inoculated into bioreactors to a starting OD600 of 0.2. 3 biological replicates (independent cultures) were grown in each medium. RNA samples were obtained at 4 time points, corresponding to exponential (Exp), transitional (Trans), stationary (Stat1) and late stationary (Stat2) growth phases.
2014-07-18 | E-GEOD-59397 | biostudies-arrayexpress
Project description:The conversion of sugars in lignocellulosic hydrolysates to bioethanol represents an industrially relevant system for understanding microbial physiology associated with production of bio-based fuels and chemicals. To this end we have developed a new version of synthetic hydrolysate (SynH) modeled on highly concentrated 9% AFEX-pretreated cornstove hydrolysate (ACSH) with and without lignocellulose-derived inhibitors (LDIs) added, termed SynH3 and SynH3- respectively. We profiled the cellular responses of xylose-utilizing Z. mobilis 2032 grown in both SynH3- and SynH3 via collection and analysis of multiple omics-based data (multiomics) including transcriptomics, proteomics, and metabolomics. Our study was focused on answering the following two questions. First, how does Z. mobilis respond to LDIs in SynH3 and how does this compare to our previous studies with E. coli in 6% ACSH SynH? Second, what is the potential cause for the poor xylose conversion in the presence of LDIs? Addressing these questions will provide critical information for engineering of Z. mobilis strains with improved productivities in lignocellulosic hydrolysates.
2019-10-25 | GSE135718 | GEO
Project description:Efficient microbial conversion of lignocellulosic hydrolysates to biofuels is a key barrier to the economically viable deployment of lignocellulosic biofuels. A chief contributor to this barrier is the impact on microbial processes and energy metabolism of lignocellulose-derived inhibitors, including phenolic carboxylates, phenolic amides (for ammonia-pretreated biomass), phenolic aldehydes, and furfurals. To understand the bacterial pathways induced by inhibitors present in ammonia-pretreated biomass hydrolysates, which are less well studied than acid-pretreated biomass hydrolysates, we developed and exploited synthetic mimics of ammonia-pretreated corn stover hydrolysate (ACSH). To determine regulatory responses to the inhibitors normally present in ACSH, we measured transcript and protein levels in an Escherichia coli ethanologen using RNA-seq and quantitative proteomics during fermentation to ethanol of synthetic hydrolysates containing or lacking the inhibitors. Our study identified four major regulators mediating these responses, the MarA/SoxS/Rob network, AaeR, FrmR, and YqhC. Induction of these regulons was correlated with a reduced rate of ethanol production, buildup of pyruvate, depletion of ATP and NAD(P)H, and an inhibition of xylose conversion. The aromatic aldehyde inhibitor 5M-bM-^@M-^Qhydroxymethylfurfural appeared to be reduced to its alcohol form by the ethanologen during fermentation, whereas phenolic acid and amide inhibitors were not metabolized. Together, our findings establish that the major regulatory responses to lignocellulose-derived inhibitors are mediated by transcriptional rather than translational regulators, suggest that energy consumed for inhibitor efflux and detoxification may limit biofuel production, and identify a network of regulators for future synthetic biology efforts. E.coli ethanologen strain GLBRCE1 or GLBRCE1 lacking the plasmid-borne PET cassette (GLBRCE1_pBBR) was grown in AFEX corn stover hydrolysate (ACSH) Fermentations were carried out in 3 L bioreactors (Applikon Biotechnology) containing 2.45 L of ACSH, and cultures were diluted into ACSH with initial OD at 0.2, grown anaerobically overnight, and then inoculated into bioreactors to a starting OD600 of 0.2. One biological replicate was grown in each medium. RNA samples were obtained at 3 time points, corresponding to exponential (Exp), transitional (Trans), and stationary (Stat) growth phases.
2014-07-18 | E-GEOD-58902 | biostudies-arrayexpress