Elementary mode analysis and metabolic flux analysis of L-glutamate biosynthesis byCorynebacterium glutamicum

Chen, Ning; Du, Jun; Liu, Hui; Xu, Qingyang

doi:10.1007/bf03178334

Cited by 13 publications

(11 citation statements)

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“…For many important applications of ARG, its industrial level production has become an important task. It can be produced by microbial fermentation at an industrial scale [ 9 ] as for other amino acids such as L-glutamate (GLU) [ 10 ], L-lysine (LYS) [ 11 ], L-tryptophan (TRP) [ 12 ], L-valine (VAL) [ 13 ], L-threonine (THR) [ 14 ] and L-alanine (ALA) [ 15 ]. For these amino acids, model organisms such as Corynebacterium glutamicum [ 16 ] and Escherichia coli [ 17 ] have been widely used as production hosts, while ARG production has been performed using B. subtilis [ 18 ] and C. glutamicum [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Metabolic engineering of microorganisms for the production of L-arginine and its derivatives

Shin

Lee

2014

Microb Cell Fact

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L-arginine (ARG) is an important amino acid for both medicinal and industrial applications. For almost six decades, the research has been going on for its improved industrial level production using different microorganisms. While the initial approaches involved random mutagenesis for increased tolerance to ARG and consequently higher ARG titer, it is laborious and often leads to unwanted phenotypes, such as retarded growth. Discovery of L-glutamate (GLU) overproducing strains and using them as base strains for ARG production led to improved ARG production titer. Continued effort to unveil molecular mechanisms led to the accumulation of detailed knowledge on amino acid metabolism, which has contributed to better understanding of ARG biosynthesis and its regulation. Moreover, systems metabolic engineering now enables scientists and engineers to efficiently construct genetically defined microorganisms for ARG overproduction in a more rational and system-wide manner. Despite such effort, ARG biosynthesis is still not fully understood and many of the genes in the pathway are mislabeled. Here, we review the major metabolic pathways and its regulation involved in ARG biosynthesis in different prokaryotes including recent discoveries. Also, various strategies for metabolic engineering of bacteria for the overproduction of ARG are described. Furthermore, metabolic engineering approaches for producing ARG derivatives such as L-ornithine (ORN), putrescine and cyanophycin are described. ORN is used in medical applications, while putrescine can be used as a bio-based precursor for the synthesis of nylon-4,6 and nylon-4,10. Cyanophycin is also an important compound for the production of polyaspartate, another important bio-based polymer. Strategies outlined here will serve as a general guideline for rationally designing of cell-factories for overproduction of ARG and related compounds that are industrially valuable.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-014-0166-4) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Metabolic engineering of microorganisms for the production of L-arginine and its derivatives

Shin

Lee

2014

Microb Cell Fact

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“…Generally, a metabolically engineered microbe has a reduced growth rate compared to its parental strain ( Jung et al , 2012 ). Studies report that ldhA deletion in severals microbes reduced cell growth ( Yang et al , 1999 ; Chen et al , 2009 ; Fiedler et al , 2011 ). Although the biomass of GDK-9Δ ldh was slightly lower than that of the GDK-9 in early-stage cultures, both strains yielded similar biomass as the incubation time increased, indicating that ldhA deletion did not adversely affect the bacterial growth.…”

Section: Discussionmentioning

confidence: 99%

“…In C. glutamicum , pyruvate is a branch point of glucose catabolism, since it is the portal to several metabolic pathways ( Chen et al , 2009 ). Significantly, pyruvate can enter the TCA cycle in two ways: by condensation with CO 2 to form a dicarboxylic acid, or by oxidative decarboxylation to acetyl CoA.…”

Section: Introductionmentioning

confidence: 99%

Reducing lactate secretion by ldhA Deletion in L-glutamate- producing strain Corynebacterium glutamicum GDK-9

Zhang¹,

Guan²,

Liang³

et al. 2014

Braz. J. Microbiol.

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L-lactate is one of main byproducts excreted in to the fermentation medium. To improve L-glutamate production and reduce L-lactate accumulation, L-lactate dehydrogenase-encoding gene ldhA was knocked out from L-glutamate producing strain Corynebacterium glutamicum GDK-9, designated GDK-9ΔldhA. GDK-9ΔldhA produced approximately 10.1% more L-glutamate than the GDK-9, and yielded lower levels of such by-products as α-ketoglutarate, L-lactate and L-alanine. Since dissolved oxygen (DO) is one of main factors affecting L-lactate formation during L-glutamate fermentation, we investigated the effect of ldhA deletion from GDK-9 under different DO conditions. Under both oxygen-deficient and high oxygen conditions, L-glutamate production by GDK-9ΔldhA was not higher than that of the GDK-9. However, under micro-aerobic conditions, GDK-9ΔldhA exhibited 11.61% higher L-glutamate and 58.50% lower L-alanine production than GDK-9. Taken together, it is demonstrated that deletion of ldhA can enhance L-glutamate production and lower the unwanted by-products concentration, especially under micro-aerobic conditions.

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“…EMA provides all feasible steady state flux distributions of a metabolic network in a single analysis and enables the assessment of maximum product yields as well as the determination of the ideal flux distribution in a network during optimal production. The approach was previously applied to the development of a range of fermentation products, such as glutamate, methionine, succinate, isobutanol and other compounds (Diniz et al, 2006, Krömer et al, 2006, Chen et al, 2009, Chen et al, 2010, Li et al, 2012, Gruchattka & Kayser, 2015.…”

Section: Introductionmentioning

confidence: 99%

Engineering yeast shikimate pathway towards production of aromatics: rational design of a chassis cell using systems and synthetic biology

Averesch¹

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Aromatic building blocks are amongst the most important bulk feedstocks in the chemical industry. As these compounds are commonly derived from petrochemistry, obtaining them is becoming more and more a matter of costs and sustainability. Biochemistry gives rise to a wealth of compounds that can potentially replace current petroleum-based chemicals or be used for novel materials. The aromatic compounds para-aminobenzoic acid (pABA) and para-hydroxybenzoic acid (pHBA) and the aromatics derived compound cis,cismuconic acid (ccMA) can be precursors for, but are not limited to, terephthalic or/and adipic acid. These are essential feedstocks for the production of PET and nylon. The three compounds can be derived from the shikimate pathway, an anabolic pathway leading to the biosynthesis of aromatic amino acids, present in certain prokaryotes and eukaryotes, including fungi. By combination of metabolic modelling with genetic engineering, a microbial production system based on the yeast Saccharomyces cerevisiae can be designed, which effectively channels flux into the target compounds.In order to develop a competitive bio-based process, yields, titers and rates need to be maximized. While productivity or rates in a process can be altered using genetic engineering, carbon yield, and pathway feasibility are stoichiometrically and thermodynamically predetermined. Both limitations need to be considered when designing a microbial production system. For formation of adipic acid and precursors many bio-based routes exists. More rational than just picking one for in vivo studies rather all available biochemical pathways were examined in silico using metabolic modelling. To compare theoretical yields and reaction thermodynamics an interface that allowed network-embedded thermodynamic analysis of elementary flux modes was developed. This allowed distinguishing between thermodynamically feasible and infeasible flux distributions. Feasible maximum theoretical product carbon yields were substantially different in E. coli and S. cerevisiae metabolic models and ranged from 32% to 92%. Further, many pathways appeared to be restricted by a thermodynamic equilibrium lying on the substrate side, some even infeasible.The only routes that deliver significant product yields and were thermodynamically favoured were shikimate pathway based. Being currently of strong scientific interest, recent implementations of these pathways in E. coli and S. cerevisiae were evaluated and strain construction strategies optimized, using the concept of constrained minimal cut-sets.Especially in S. cerevisiae a single non-obvious knock-out target allowed coupling of growth to product formation; in particular, the deletion of the pyruvate kinase reaction resulted in a minimum yield constraint of 28%.Though unique to shikimate pathway, this strategy is transferrable to other products which are derived from chorismate and also involve the formation of pyruvate as a by-product. This applies to pHBA. With further optimizations, the strategy was applied in...

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Elementary mode analysis and metabolic flux analysis of L-glutamate biosynthesis byCorynebacterium glutamicum

Cited by 13 publications

References 20 publications

Metabolic engineering of microorganisms for the production of L-arginine and its derivatives

Metabolic engineering of microorganisms for the production of L-arginine and its derivatives

Reducing lactate secretion by ldhA Deletion in L-glutamate- producing strain Corynebacterium glutamicum GDK-9

Engineering yeast shikimate pathway towards production of aromatics: rational design of a chassis cell using systems and synthetic biology

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