Uncoupling growth and product formation kinetics to design improved strains for recombinant protein production in escherichia coli
Ontology highlight
ABSTRACT:
ORGANISM(S): Escherichia coli
PROVIDER: GSE29486 | GEO | 2011/06/01
SECONDARY ACCESSION(S): PRJNA141645
REPOSITORIES: GEO
Similar Datasets
Project description:The ability to control the synthesis of products in the absence of cell division remains an attractive alternative for the optimization of microbial processes. If this could be achieved, it would dramatically expand the productivity of many microbial processes by increasing product synthesis in the absence of an increase in cell mass. In the present work we have looked at the factors involved in the design of a host where the fluxes would be channeled towards product formation rather than biomass synthesis. To identify the genes responsible for diverting the metabolic flux specifically towards product formation we have used for this study is quiescent-cell (Q-cell) expression system, in which a plasmid-encoded protein is expressed in nongrowing but metabolically active cells. These cells channel the metabolic flux towards recombinant protein production and therefore the specific product yield per unit biomass is significantly higher. Indole which is previously known to be a signalling molecule is here used as an inducer of Quiescence. E.coli L-Asparaginase is used as a model protein in this work. Fed batch cultures were carried out in Sartorius BIOSTAT B plus 5liter bioreactor. The data acquisition was done with the MFCS Shell software (version) provided with the bioreactor. The Sartorius BIOSTAT B plus had proportional integral derivative-based control loops for temperature, pH, antifoam, and dissolved-oxygen (DO) regulation. The culture was grown in a batch mode till 10-12 OD (µ=0.5) and then the feed was attached. In the next hour the culture was induced for product formation with 1M IPTG. In case of Q culture quiescence was induced with 0.5M Indole just 5min after induction with IPTG. Post induction every hour samples were collected and frozen with liquid nitrogen and stored at -80ºC for further analytical use. Total RNA extraction, RNA quality control (Agilent BioAnalyser), total RNA labeling, microarray hybridization and scanning were performed according to the Affymetrix GeneChip Expression analysis .
2011-05-31 | E-GEOD-29486 | biostudies-arrayexpress
Project description:Proliferating cancer cells are addicted to glutamine for biomass synthesis and energy generation. We here enzymatically deplete circulating glutamine in mice and report how cancer cells adapt to low circulating glutamine and document immunological changes in the tumor microenvironment (TME) upon glutamine depletion in CT26 tumor model. We show that cancer cells adapt to low glutamine by diverting intracellular glutamine flux to nucleotide synthesis and downregulating global translation. Through immune cell deconvolution and GSEA, we show that systemic glutamine depletion is immunsosuppressive and marked by accumulaton of PMN-MDSC in the TME.
2024-04-16 | GSE247472 | GEO
Project description:Saccharomyces cerevisiae is an established microbial host for the production of non-native compounds. The synthesis of these compounds typically demands energy and competes with growth for carbon and energy substrate. Uncoupling product formation form growth would benefit product yields and decrease formation of by-product biomass. Studying non-growing metabolically-active yeast cultures provides a first step towards developing S. cerevisiae as a non-growing, robust cell factory. Non-growing metabolically-active cultures can be obtained in retentostat, a glucose-limited, continuous bioreactor system in which biomass accumulates while spent medium is constantly removed. Hitherto retentostat cultures of S. cerevisiae have only been reported under anaerobiosis, condition inappropriate for the production of energy-demanding products. The present study, using retentostat cultures, explores the physiology of non-dividing, fully respiring S. cerevisiae, focusing on industrially-relevant features. Following model-aided experimental design, retentostat cultivations were optimized for accelerated but smooth transition of S. cerevisiae from exponential growth to near-zero growth rates. During 20 days in retentostat the biomass concentration increased, leading very slow growth rates (specific growth rates below 0.001 h-1) but high culture viability (over 80% of viable cells). The maintenance requirement (mATP) was estimated at 0.64 mmolATP.gX-1.h-1, which is remarkably ca. 35% lower than the mATP measured in anaerobic retentostat cultures. Transcriptional down-regulation of genes involved in biosynthesis and up-regulation of stress-responsive genes towards near-zero growth rates corresponded well with data from anaerobic retentostats. More striking was the extreme heat-shock tolerance of S. cerevisiae, which exceeded by far previously reported heat shock tolerance of notoriously robust yeast cultures such as stationary phase cultures. Furthermore, while the metabolic fluxes in the retentostats were relatively low as a result of extreme caloric restriction, off-line measurements revealed that S. cerevisiae retained a high catabolic capacity. The high viability and extreme heat-shock tolerance revealed the robustness of S. cerevisiae at near-zero growth in retentostat. In addition, the relatively low maintenance requirements and high metabolic capacity under severe calorie restriction underline the potential of S. cerevisiae as a non-dividing microbial cell factory for the production of energy-intensive compounds. The retentostat is a promising tool to identify the molecular basis of this extreme robustness. The goal of the present study is to investigate the physiology of aerobic fully respiring S. cerevsiae at near-zero growth rates. Fundamental but industrially-relevant questions were addressed thanks to the design, implementation and study of aerobic retentostat cultivations enabling a rapid but smooth transition of S. cerevisiae from exponential growth to near-zero growth rates.
2016-06-01 | E-GEOD-77842 | biostudies-arrayexpress
Project description:Saccharomyces cerevisiae is an established microbial host for the production of non-native compounds. The synthesis of these compounds typically demands energy and competes with growth for carbon and energy substrate. Uncoupling product formation form growth would benefit product yields and decrease formation of by-product biomass. Studying non-growing metabolically-active yeast cultures provides a first step towards developing S. cerevisiae as a non-growing, robust cell factory. Non-growing metabolically-active cultures can be obtained in retentostat, a glucose-limited, continuous bioreactor system in which biomass accumulates while spent medium is constantly removed. Hitherto retentostat cultures of S. cerevisiae have only been reported under anaerobiosis, condition inappropriate for the production of energy-demanding products. The present study, using retentostat cultures, explores the physiology of non-dividing, fully respiring S. cerevisiae, focusing on industrially-relevant features. Following model-aided experimental design, retentostat cultivations were optimized for accelerated but smooth transition of S. cerevisiae from exponential growth to near-zero growth rates. During 20 days in retentostat the biomass concentration increased, leading very slow growth rates (specific growth rates below 0.001 h-1) but high culture viability (over 80% of viable cells). The maintenance requirement (mATP) was estimated at 0.64 mmolATP.gX-1.h-1, which is remarkably ca. 35% lower than the mATP measured in anaerobic retentostat cultures. Transcriptional down-regulation of genes involved in biosynthesis and up-regulation of stress-responsive genes towards near-zero growth rates corresponded well with data from anaerobic retentostats. More striking was the extreme heat-shock tolerance of S. cerevisiae, which exceeded by far previously reported heat shock tolerance of notoriously robust yeast cultures such as stationary phase cultures. Furthermore, while the metabolic fluxes in the retentostats were relatively low as a result of extreme caloric restriction, off-line measurements revealed that S. cerevisiae retained a high catabolic capacity. The high viability and extreme heat-shock tolerance revealed the robustness of S. cerevisiae at near-zero growth in retentostat. In addition, the relatively low maintenance requirements and high metabolic capacity under severe calorie restriction underline the potential of S. cerevisiae as a non-dividing microbial cell factory for the production of energy-intensive compounds. The retentostat is a promising tool to identify the molecular basis of this extreme robustness.
2016-06-01 | GSE77842 | GEO
Project description:We propose a strain engineering approach for synthesizing sedoheptulose using glucose as sole feedstock. The gene pfkA encoding 6-phosphofructokinase in Corynebacterium glutamicum was inactivated to direct the carbon flux towards pentose phosphate pathway in the cellular metabolic network. This genetic modification successfully enabled the synthesis of sedoheptulose from glucose. Additionally, we identified key enzymes responsible for product formation through transcriptome analysis, and their corresponding genes were overexpressed, resulting in a further 20% increase in sedoheptulose production.
2024-05-31 | GSE254540 | GEO
Project description:Chassis strain suitable for producing multiple compounds is a central concept in synthetic biology. Design of a chassis using computational, first-principle, models is particularly attractive due to the predictability and control it offers, including against phenotype reversal due to adaptive mutations. Yet, the theory of model-based chassis design has not been put to experimental test. Here, we report two Saccharomyces cerevisiae chassis strains for dicarboxylic acid production based on genome-scale metabolic modelling. The chassis strain, harboring gene knockouts in serine biosynthesis and in pentose-phosphate pathway, is geared for higher flux towards three target products - succinate, fumarate and malate - but does not appreciably secrete any. Introducing modular product-specific mutations resulted in improved secretion of the corresponding acid as predicted by the model. Adaptive laboratory evolution of the chassis-derived producer cells further improved production for succinate and fumarate attesting to the evolutionary robustness of the underlying growth-product coupling. In the case of malate, which exhibited decreased production during evolution, the multi-omics analysis revealed flux bypass at peroxisomal malate dehydrogenase not accounted in the model. Transcriptomics, proteomics and metabolomics analysis showed overall concordance with the flux re-routing predicted by the model. Together, our results provide experimental evidence for model-based design of microbial chassis and have implications for computer-aided design of microbial cell factories.
2021-07-20 | PXD020611 | Pride
Project description:In microbial production of non-catabolic products, a loss of production capacity upon long-term cultivation (for example, chemostat), a phenomenon called strain degeneration, is nearly always observed. In this study, a systems biology approach (monitoring changes from gene to produced flux) was used to study degeneration of penicillin production by Penicillium chrysogenum in ethanol-limited chemostat fermentations where the biomass specific penicillin production rate decreased 10-fold within 30 generations. Results showed that the copy number of penicillin gene clusters and expression levels of central metabolism showed little decrease. With respect to penicillin production, major changes were observed: a strong downregulation of the cysteine pathway in agreement with its nearly 10-fold flux reduction. Also, levels of ACVS and IPNS, two penicillin pathway enzymes, and the penicillin transport capacity decreased many fold. This indicates that degeneration is caused by changed regulation of post-translational modifications or an increased protein degradation rate of these proteins. Continued subcultivation of a degenerated culture resulted in partial recovery of the biomass specific penicillin production rate, however, it was still 5-fold lower than the peak biomass specific penicillin production rate.
2011-06-10 | GSE24212 | GEO
Project description:Microbial biomass has emerged as a promising sustainable protein alternative. The cultivation conditions affect the composition of microbial cells, and hence their quality and nutritional value. Here, we investigated the relationship between growth rate, substrate availability and cell composition and size of Cupriavidus necator and Komagataella phaffii. Biomass with decreased nucleic acid and increased protein content was produced at low growth rates. Conversely, high rates resulted in larger cells, which could enable more efficient biomass harvesting. The proteome allocation varied across the different growth rates, with more ribosomal proteins at higher rates. Considering the distinct amino acid profiles established for the different cellular components, variations in their abundance impacts the product quality leading to higher cysteine and phenylalanine content at low growth rates. In summary, we demonstrate tradeoffs between nutritional quality and production rate, and we discuss that techno-functional food properties should be considered when designing microbial biomass production processes.
2024-01-26 | PXD041491 | Pride
Project description:In microbial production of non-catabolic products, a loss of production capacity upon long-term cultivation (for example, chemostat), a phenomenon called strain degeneration, is nearly always observed. In this study, a systems biology approach (monitoring changes from gene to produced flux) was used to study degeneration of penicillin production by Penicillium chrysogenum in ethanol-limited chemostat fermentations where the biomass specific penicillin production rate decreased 10-fold within 30 generations. Results showed that the copy number of penicillin gene clusters and expression levels of central metabolism showed little decrease. With respect to penicillin production, major changes were observed: a strong downregulation of the cysteine pathway in agreement with its nearly 10-fold flux reduction. Also, levels of ACVS and IPNS, two penicillin pathway enzymes, and the penicillin transport capacity decreased many fold. This indicates that degeneration is caused by changed regulation of post-translational modifications or an increased protein degradation rate of these proteins. Continued subcultivation of a degenerated culture resulted in partial recovery of the biomass specific penicillin production rate, however, it was still 5-fold lower than the peak biomass specific penicillin production rate. Prolonged chemostat cultivations up to 500 hours (30 generations) with ethanol as the sole limiting carbon source were performed because degeneration is found to be more pronounced with ethanol as a limiting sole carbon source compared to glucose. Measurements included genome level (number of penicillin gene clusters), genome-wide transcriptome, protein levels of penicillin pathway enzymes, number of peroxisomes (microbodies where part of the penicillin pathway occurs), metabolome (of central metabolism, nucleotides, penicillin pathway intermediates including intracellular PAA and PenG) and fluxome.
2011-06-10 | E-GEOD-24212 | biostudies-arrayexpress
Project description:Cells must appropriately sense and integrate multiple metabolic resources to commit to proliferation. Here, we report that cells regulate nitrogen (amino acid) and carbon metabolic homeostasis through tRNA U34-thiolation. Despite amino acid sufficiency, tRNA-thiolation deficient cells appear amino acid starved. In these cells, carbon flux towards nucleotide synthesis decreases, and trehalose synthesis increases, resulting in metabolic a starvation-signature. Thiolation mutants have only minor translation defects. However, these cells exhibit strongly decreased expression of phosphate homeostasis genes, mimicking a phosphate-limited state. Reduced phosphate enforces a metabolic switch, where glucose-6-phosphate is routed towards storage carbohydrates. Notably, trehalose synthesis, which releases phosphate and thereby restores phosphate availability, is central to this metabolic rewiring. Thus, cells use thiolated tRNAs to perceive amino acid sufficiency, and balance amino acid and carbon metabolic flux to maintain metabolic homeostasis, by controlling phosphate availability. These results further biochemical explain how phosphate availability determines a switch to a ‘starvation-state’.
2018-12-28 | GSE124428 | GEO