Improved Fermentative Production of Gamma-Aminobutyric Acid via the Putrescine Route: Systems Metabolic Engineering for Production From Glucose, Amino Sugars, and Xylose
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ABSTRACT:
ORGANISM(S): Corynebacterium glutamicum Corynebacterium glutamicum ATCC 13032
PROVIDER: GSE81695 | GEO | 2016/05/21
SECONDARY ACCESSION(S): PRJNA322319
REPOSITORIES: GEO
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Project description:Corynebacterium glutamicum shows a great potential for the production of gamma-aminobutyric acid (GABA) from glucose fermentation via putrescine. GABA, a non-protein amino acid widespread in nature, is a component of pharmaceuticals, foods and the biodegradable plastic polyamide 4. Here, the effect of GABA in the growth of C. glutamicum was evaluated. It was estimated that the presence 1.1 M of GABA in the medium reduces the maximum growth rate of C. glutamicum to half. It was also shown that the presence of GABA in the medium negatively affects the growth of C. glutamicum in ethanol as sole carbon source. Furthermore, a new route for the production of GABA in C. glutamicum was established. GABA production from glucose fermentation via putrescine was achieved by plasmid-based overexpression of putrescine transaminase (PatA) and gamma-aminobutyraldehyde dehydrogenase (PatD) in a putrescine production strain. The resultant strain can produce 5.3 ± 0.1 g L-1 of GABA. GABA production was improved by avoiding the formation of N-acetylputrescine and by reducing the amount of nitrogen in CGXII medium. Deletion of the genes responsible for GABA catabolism and GABA re-uptake led to an increase in the GABA production of 21% achieving a titer 8.0 ± 0.3 g L-1 and an increase in the volumetric productivity of 41% reaching a productivity of 0.31 g L-1 h-1, the highest volumetric productivity achieved so far for GABA production in C. glutamicum from glucose fermentation in flasks fermentations. The results obtained hitherto are very promising and competitive compared to the traditional pathway for the production of GABA.
2015-10-22 | GSE74258 | GEO
Project description:Ciprofloxacin, an inhibitor of bacterial gyrase and topoisomerase IV, was shown to inhibit growth of C. glutamicum with concomitant excretion of L-glutamate. C. glutamicum strains overproducing L-lysine, L-arginine, L-ornithine, and putrescine, respectively, produced L-glutamate instead of the desired amino acid when exposed to ciprofloxacin. Even in the absence of the putative L-glutamate exporter gene yggB, ciprofloxacin effectively triggered L-glutamate production. When C. glutamicum wild type was cultivated under nitrogen-limiting conditions, 2-oxoglutarate rather than L-glutamate was produced as consequence of exposure to ciprofloxacin. Transcriptome analysis revealed that ciprofloxacin increased RNA levels of genes involved in DNA synthesis, repair and modification. Enzyme assays showed that 2-oxoglutarate dehydrogenase activity was decreased due to ciprofloxacin addition. Here, it was shown for the first time that production of L-glutamate by C. glutamicum may be triggered by an inhibitor of DNA synthesis and L-glutamate titers of up to 37 ± 1 mM and a substrate specific L-glutamate yield of 0.13 g/g were reached.
2016-01-26 | GSE77189 | GEO
Project description:The dicarboxylic acid glutarate is gaining attention in the chemical and pharmaceutical industry as promising building-block. Synthesis of glutarate via microbial fermentation is a desirable aim which will allow the production of biopolymers avoiding fossil raw materials. Here, by rational metabolic engineering of the biofactory microorganism Corynebacterium glutamicum the fermentative production of glutarate from glucose was established. Modifications focused on increase glucose consumption and reduce by-products formation together with the heterologous overexpression of the L-lysine decarboxylase, putrescine transaminase and putrescine dehydrogenase genes from E. coli in the L-lysine producer GRLys1 allowed production the glutarate precursor 5-aminovalerate. Additional heterologous overexpression of 5-aminovalerate amino transferase and glutarate-semialdehyde dehydrogenase genes from C. glutamicum and three Pseudomonas species enabled glutarate synthesis from glucose. By coupling glutarate production with the glutamate synthesis of C. glutamicum glutarate titer improved 10%. The final strain was tested in a glucose-based fed-batch fermentation
2018-11-20 | GSE117175 | GEO
Project description:Polyamines (putrescine, spermidine, and spermine) are major organic polycations essential for a wide spectrum of cellular processes. The cells require mechanisms to maintain homeostasis of intracellular polyamines to prevent otherwise severe adverse effects. We performed a detailed transcriptome profile analysis of P. aeruginosa in response to agmatine and putrescine with an emphasis in polyamine catabolism. Agmatine serves as precursor compound for putrescine (and hence spermidine and spermine), which was proposed to convert into GABA and succinate before entering the TCA cycle in support of cell growth as the sole source of carbon and nitrogen. Two acetylpolyamine amidohydrolases, AphA and AphB, were identified to be involved in the conversion of agmatine into putrescine. Enzymatic products of AphA were confirmed by mass spectrometry analysis. Interestingly, the alanine-pyruvate cycle was shown indispensable for polyamine utilization. The newly identified dadRAX locus, encoding the regulator, alanine transaminase and racemase respectively, coupled with SpuC, the major putrescine-pyruvate transaminase, were key components to maintain alanine homeostasis. Corresponding mutant strains were severely hampered in polyamine utilization. On the other hand, the alternative gamma-glutamylation pathway for the conversion of putrescine into GABA was also discussed. Subsequently, GabD, GabT and PA5313 were identified for GABA utilization. Growth defect of PA5313 gabT double mutant in GABA suggested the importance of these two transaminases. The succinic-semialdehyde dehydrogenase activity of GabD and its induction by GABA was also demonstrated in vitro. Polyamine utilization in general was proven independent of the PhoPQ two-component system even the expression of which was induced by polyamines. Multiple potent catabolic pathways as depicted in this study could serve pivotal roles in control of intracellular polyamine levels. Keywords: Metabolism, polyamines, agmatine, putrescine, glutamate, phoPQ.
2008-04-07 | GSE9926 | GEO
Project description:Polyamines (putrescine, spermidine, and spermine) are major organic polycations essential for a wide spectrum of cellular processes. The cells require mechanisms to maintain homeostasis of intracellular polyamines to prevent otherwise severe adverse effects. We performed a detailed transcriptome profile analysis of P. aeruginosa in response to agmatine and putrescine with an emphasis in polyamine catabolism. Agmatine serves as precursor compound for putrescine (and hence spermidine and spermine), which was proposed to convert into GABA and succinate before entering the TCA cycle in support of cell growth as the sole source of carbon and nitrogen. Two acetylpolyamine amidohydrolases, AphA and AphB, were identified to be involved in the conversion of agmatine into putrescine. Enzymatic products of AphA were confirmed by mass spectrometry analysis. Interestingly, the alanine-pyruvate cycle was shown indispensable for polyamine utilization. The newly identified dadRAX locus, encoding the regulator, alanine transaminase and racemase respectively, coupled with SpuC, the major putrescine-pyruvate transaminase, were key components to maintain alanine homeostasis. Corresponding mutant strains were severely hampered in polyamine utilization. On the other hand, the alternative gamma-glutamylation pathway for the conversion of putrescine into GABA was also discussed. Subsequently, GabD, GabT and PA5313 were identified for GABA utilization. Growth defect of PA5313 gabT double mutant in GABA suggested the importance of these two transaminases. The succinic-semialdehyde dehydrogenase activity of GabD and its induction by GABA was also demonstrated in vitro. Polyamine utilization in general was proven independent of the PhoPQ two-component system even the expression of which was induced by polyamines. Multiple potent catabolic pathways as depicted in this study could serve pivotal roles in control of intracellular polyamine levels. Experiment Overall Design: P. aeruginosa PAO1 was grown aerobically in minimal medium P with 350 rpm shaking at 37C, in the presence of L-glutamate alone or with the addition of putrescine, agmatine or GABA at 20 mM. Cells were harvested when the optical density at 600 nm reached 0.5~0.6 by centrifugation for 5 minutes at 4C. Total RNA samples were isolated by RNeasy purification kit following instructions of the manufacturer (Qiagen). Reverse transcription for cDNA synthesis, fragmentation by DNase I treatment, cDNA probe labeling and hybridization were performed according to the instructions of GeneChip manufacturer (Affymetrix). Data were processed by Microarray Suite 5.0 software normalizing the absolute expression signal values of all chips to a target intensity of 500. GeneSpring software (Silicon Genetics) was used for expression pattern analysis and comparison. Only genes showing consistent expression profiles in duplicates were selected for further analysis.
2008-06-16 | E-GEOD-9926 | biostudies-arrayexpress
Project description:Background: Of the many neurotransmitters in humans, gamma-aminobutyric acid (GABA) shows potential for improving several mental health indications such as stress and anxiety. The microbiota-gut-brain axis is an important pathway for GABAergic effects, as microbially-secreted GABA within the gut can affect host mental functionhealth outcomes. Understanding the molecular characteristics of GABA production by microbes within the gut can offer insight to novel therapies for mental health. Results: Three strains of Levilactobacillus brevis with syntenous glutamate decarboxylase (GAD) operons were evaluated for overall growth, glutamate utilization, and GABA production in typical synthetic growth media supplemented with monosodium glutamate (MSG). Levilactobacillus brevis Lbr-6108 (Lbr-6108) and Levilactobacillus brevis Lbr-35 (Lbr-35) had similar growth profiles but differed significantly in GABA secretion and acid resistance. Lbr-6108 produced GABA early, within the growth phase, and produced significantly more GABA than Lbr-35 and the type strain Levilactobacillus brevis ATCC 14689 after the stationary phase. The global gene expression during GABA production was determined by RNA sequencing at several timepoints. The GAD operon, responsible for GABA production and secretion, activated in Lbr-6108 after only six hours of fermentation and continued throughout the stationary phase. Furthermore, Lbr-6108 activated many different acid resistance mechanisms concurrently, which contribute to acid tolerance and energy production. In contrast, Lbr-35, which has a genetically similar GAD operon, including two copies of the GAD gene, showed no upregulation of the GAD operon, even when cultured with MSG. Conclusions: This study is the first to evaluate whole transcriptome changes in L. brevis during GABA production over multiple timepoints. The concurrent expression of multiple acid-resistance mechanisms reveals niche-specific metabolic functionality between common human commensals and highlights the complex regulation of GABA metabolism in this important microbial species. Furthermore, the increased and rapid GABA production of Lbr-6108 highlights the strain’s potential as a therapeutic and the overall value of screening microbes for effector molecule output.
2021-08-07 | GSE181504 | GEO
Project description:Oryza sativa cv. Nipponbare was engineered to over-express a barley alanine aminotransferase (alaAT) gene using the promoter (OsANT1) from a rice aldehyde dehydrogenase gene that expresses in roots. We use biotechnology to improve the nitrogen use efficiency of rice by over-expressing alaAT in a tissue specific (root) manner. The AlaAT enzyme is a reversible aminotransferase that is linked to both C and N metabolism since it uses pyruvate plus glutamate to produce alanine and 2-oxoglutarate, and visa versa.
2013-10-25 | GSE48549 | GEO
Project description:Oryza sativa cv. Nipponbare was engineered to over-express a barley alanine aminotransferase (alaAT) gene using the promoter (OsANT1) from a rice aldehyde dehydrogenase gene that expresses in roots. We are using biotechnology to improve the nitrogen use efficiency of rice by over-expressing alaAT in a tissue specific (root) manner. The AlaAT enzyme is a reversible aminotransferase that is linked to both C and N metabolism since it uses pyruvate plus glutamate to produce alanine and 2-oxoglutarate, and visa versa.
2012-07-27 | GSE39687 | GEO
Project description:The Gram-positive soil bacterium Corynebacterium glutamicum is widely used in industrial fermentative processes for the production of amino acids. The world production of L-lysine has surpassed 2 million tons per year. Glucose is taken up into the C. glutamicum cell by the phosphotransferase system PTS which can be replaced and/or enhanced by a permease and a glucokinase. Heterologous expression of the gene for the high-affinity glucose permease from Streptomyces coelicolor and of the Bacillus subitilis glucokinase gene fully compensated for the absence of the PTS in ï??hpr strains and strains grew as fast with glucose as C. glutamicum wild type. Growth of PTS-positive strains with glucose was accelerated when the endogenous inositol permease IolT2 and the glucokinase from Bacillus subtilis were overproduced using plasmid pEKEx3-IolTBest. When the genome-reduced C. glutamicum strain GRLys1 carrying additional in-frame deletions of sugR and ldhA to derepress glycolytic and PTS genes and to circumvent formation of L-lactate as by-product was transformed with this plasmid, a 40% higher L-lysine titer and a 30% higher volumetric productivity as compared to GRLys1(pEKEx3) resulted. The non-proteinogenic amino acid pipecolic acid (L-PA), a precursor of immunosuppressants, peptide antibiotics or piperidine alkaloids, can be derived from L-lysine. To enable production of L-PA by the L-lysine producing strain, the L-Lysine dehydrogenase gene lysDH from Silicibacter pomeroyi and the endogenous pyrroline 5-carboxylate reductase gene proC were expressed as synthetic operon. This enabled C. glutamicum to L-PA with a yield of 0.49 ± 0.03 gg-1 and a volumetric productivity of 0.04 ± 0.00 gL-1h-1.To the best of our knowledge, this is the first fermentative process for the production of L-PA. Two conditions tested, 200 mM NaCl Vs 200 mM pipecolic supplemented in the culture medium, control experiments done with the addition of 200mM of NaCl. Four technical replicates.
2016-03-30 | E-GEOD-79690 | biostudies-arrayexpress
Project description:Background: With the increasing interest in metabolic engineering of plants using various genetic manipulation and gene editing technologies in order to enhance their growth, nutritional value and environmental adaptation, a major concern is the potential of broad and distant effects of manipulating the target gene or the metabolic step in the resulting plant. A comprehensive transcriptomic and metabolomic analysis of the product may shed some useful light in this regard. The present study used these techniques with plant cell cultures to analyze the effects of genetic manipulation of a single step in the biosynthesis of polyamines because of their well-known roles in plant growth, development and stress responses [PMID 19383098] The transcriptomes and metabolomes of a control and a high putrescine producing (HP) cell line of poplar (Populus nigra x maximowiczii) were compared using microarrays and GC/MS. The HP cells expressed an ornithine decarboxylase transgene and accumulated several-fold higher concentrations of putrescine, with only small changes in spermidine and spermine. The results show that up-regulation of a single step in the polyamine biosynthetic pathway (i.e. ornithine→putrescine) altered the expression of a broad spectrum of genes; many of them were involved in transcription, translation, membrane transport, osmoregulation, shock/stress/wounding, and cell wall metabolism. More than half of the 200 detected metabolites were significantly altered (P <0.05) in the HP cells on any day of analysis; the most noteworthy differences were in organic acids, carbohydrates and nitrogen-containing metabolites. The results provide valuable information about the role of polyamines in regulating nitrogen and carbon use pathways in cell cultures of high putrescine producing transgenic cells of poplar vs. their low putrescine counterparts. The results underscore the complexity of cellular responses to genetic perturbation of a single metabolic step related to nitrogen metabolism in plants. Combined with recent studies from our lab regarding increased putrescine production causing an increased flux of glutamate into ornithine, with accompanied increase in glutamate production by additional nitrogen and carbon assimilation; the results may be useful in designing transgenic plants with increased nitrogen use efficiency, especially in plants intended for non-food/feed applications (e.g. increased biomass production or for biofuels).
2016-03-24 | GSE79420 | GEO