18 results on '"Liu, Zhi-Qiang"'
Search Results
2. Module engineering coupled with omics strategies for enhancing D-pantothenate production in Escherichia coli.
- Author
-
Wang P, Zhou HY, Zhou JP, Li B, Liu ZQ, and Zheng YG
- Subjects
- Biosynthetic Pathways, Carbon metabolism, Fermentation, Glucose metabolism, Escherichia coli genetics, Escherichia coli metabolism, Metabolic Engineering
- Abstract
Biosynthesis of D-pantothenate has been widely studied as D-pantothenate is one kind of important vitamins used in food and pharmaceuticals. However, the engineered strain for D-pantothenate production was focused solely on the main biosynthetic pathway, while other important factors such as one carbon unit were ignored. Here the systematic modular engineering on different factors coupled with omics analysis were studied in Escherichia coli for efficient D-pantothenate production. Through reinforcing the precursor pool, refactoring the one carbon unit generation pathway, optimization of reducing power and energy supply, the D-pantothenate titer reached 34.12 g/L with the yield at 0.28 g/g glucose under fed-batch fermentation in 5-L bioreactor. With a further comparative transcriptome and metabolomics studies, the addition of citrate was implemented and 45.35 g/L D-pantothenate was accumulated with a yield of 0.31 g/g glucose. The systematic modular engineering coupled with omics studies provide useful strategies for the industrial production of D-pantothenate., (Copyright © 2022 Elsevier Ltd. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
3. Multiplex modification of Escherichia coli for enhanced β-alanine biosynthesis through metabolic engineering.
- Author
-
Wang P, Zhou HY, Li B, Ding WQ, Liu ZQ, and Zheng YG
- Subjects
- Escherichia coli genetics, Plasmids, beta-Alanine, Escherichia coli Proteins genetics, Metabolic Engineering
- Abstract
β-Alanine is the only naturally occurring β-amino acid, widely used in the fine chemical and pharmaceutical fields. In this study, metabolic design strategies were attempted in Escherichia coli W3110 for enhancing β-alanine biosynthesis. Specifically, heterologous L-aspartate-α-decarboxylase was used, the aspartate kinase I and III involved in competitive pathways were down-regulated, the β-alanine uptake system was disrupted, the phosphoenolpyruvate carboxylase was overexpressed, and the isocitrate lyase repressor repressing glyoxylate cycle shunt was delete, the glucose uptake system was modified, and the regeneration of amino donor was up-regulated. On this basis, a plasmid harboring the heterologous panD and aspB was constructed. The resultant strain ALA17/pTrc99a-panD
BS -aspBCG could yield 4.20 g/L β-alanine in shake flask and 43.94 g/L β-alanine (a yield of 0.20 g/g glucose) in 5-L bioreactor via fed-batch cultivation. These modification strategies were proved effective and the constructed β-alanine producer was a promising microbial cell factory for industrial production of β-alanine., (Copyright © 2021 Elsevier Ltd. All rights reserved.)- Published
- 2021
- Full Text
- View/download PDF
4. Comparative metabolomics analysis of amphotericin B high-yield mechanism for metabolic engineering.
- Author
-
Zhang B, Chen Y, Jiang SX, Cai X, Huang K, Liu ZQ, and Zheng YG
- Subjects
- 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase genetics, 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase metabolism, Antifungal Agents analysis, Fermentation, Industrial Microbiology methods, Mutation, Streptomyces genetics, Amphotericin B analysis, Amphotericin B biosynthesis, Antifungal Agents metabolism, Metabolic Engineering methods, Metabolic Networks and Pathways genetics, Metabolomics methods, Streptomyces metabolism
- Abstract
Background: The polyene macrocyclic compound amphotericin B (AmB) is an important antifungal antibiotic for the clinical treatment of invasive fungal infections. To rationally guide the improvement of AmB production in the main producing strain Streptomyces nodosus, comparative metabolomics analysis was performed to investigate the intracellular metabolic changes in wild-type S. nodosus ZJB20140315 with low-yield AmB production and mutant S. nodosus ZJB2016050 with high-yield AmB production, the latter of which reached industrial criteria on a pilot scale., Results: To investigate the relationship of intracellular metabolites, 7758 metabolites were identified in mutant S. nodosus and wildtype S. nodosus via LC-MS. Through analysis of metabolism, the level of 26 key metabolites that involved in carbon metabolism, fatty acids metabolism, amino acids metabolism, purine metabolism, folate biosynthesis and one carbon pool by folate were much higher in mutant S. nodosus. The enrichment of relevant metabolic pathways by gene overexpression strategy confirmed that one carbon pool by folate was the key metabolic pathway. Meanwhile, a recombinant strain with gene metH (methionine synthase) overexpressed showed 5.03 g/L AmB production within 120 h fermentation, which is 26.4% higher than that of the mutant strain., Conclusions: These results demonstrated that comparative metabolomics analysis was an effective approach for the improvement of AmB production and could be applied for other industrially or clinically important compounds as well.
- Published
- 2021
- Full Text
- View/download PDF
5. Increasement of O-acetylhomoserine production in Escherichia coli by modification of glycerol-oxidative pathway coupled with optimization of fermentation.
- Author
-
Liu P, Liu JS, Zhang B, Liu ZQ, and Zheng YG
- Subjects
- Acetyltransferases genetics, Acetyltransferases metabolism, Bacterial Proteins genetics, Bacterial Proteins metabolism, Corynebacterium glutamicum enzymology, Corynebacterium glutamicum genetics, Fermentation genetics, Metabolic Networks and Pathways genetics, Oxidation-Reduction, Escherichia coli genetics, Escherichia coli metabolism, Glycerol metabolism, Homoserine analogs & derivatives, Homoserine analysis, Homoserine genetics, Homoserine metabolism, Metabolic Engineering methods
- Abstract
Objective: O-acetylhomoserine (OAH) is an important platform chemical to produce high-valuable chemicals. To improve the production of O-acetylhomoserine from glycerol, the glycerol-oxidative pathway was investigated and the optimization of fermentation with crude glycerol was carried out., Results: The glycerol-uptake system and glycerol-oxidative pathway were modified and O-acetyltransferase from Corynebacterium glutamicum was introduced into the engineered strain to produce O-acetylhomoserine. It was found that overexpression of glycerol 3-phosphate dehydrogenase improved the OAH production to 6.79 and 4.21 g/L from pure and crude glycerol, respectively. And the higher OAH production depending on higher level of transcription of glpD. Two-step statistical approach was employed to optimize the fermentation conditions. The significant effects of glycerol, ammonium chloride and yeast extract were screened applying Plackett-Burman design and were optimized further by employing the Response Surface Methodology. Under optimized conditions, the OAH production was up to 9.42 and 7.01 g/L when pure and crude glycerol were used in shake flask cultivations, respectively., Conclusions: The enzymatic step catalyzing the oxidation of glycerol through GlpD was the key step for OAH production, which served the foundation for realization of a consistent OAH production from crude glycerol in the future.
- Published
- 2021
- Full Text
- View/download PDF
6. Multiplex Design of the Metabolic Network for Production of l-Homoserine in Escherichia coli.
- Author
-
Liu P, Zhang B, Yao ZH, Liu ZQ, and Zheng YG
- Subjects
- Biosynthetic Pathways, Escherichia coli metabolism, Homoserine metabolism, Metabolic Engineering methods
- Abstract
l-Homoserine, which is one of the few amino acids that is not produced on a large scale by microbial fermentation, plays a significant role in the synthesis of a series of valuable chemicals. In this study, systematic metabolic engineering was applied to target Escherichia coli W3110 for the production of l-homoserine. Initially, a basic l-homoserine producer was engineered through the strategies of overexpressing thrA (encoding homoserine dehydrogenase), removing the degradative and competitive pathways by knocking out metA (encoding homoserine O -succinyltransferase) and thrB (encoding homoserine kinase), reinforcing the transport system, and redirecting the carbon flux by deleting iclR (encoding the isocitrate lyase regulator). The resulting strain constructed by these strategies yielded 3.21 g/liter of l-homoserine in batch cultures. Moreover, based on CRISPR-Cas9/dCas9 (nuclease-dead Cas9)-mediated gene repression for 50 genes, the iterative genetic modifications of biosynthesis pathways improved the l-homoserine yield in a stepwise manner. The rational integration of glucose uptake and recovery of l-glutamate increased l-homoserine production to 7.25 g/liter in shake flask cultivation. Furthermore, the intracellular metabolic analysis further provided targets for strain modification by introducing the anaplerotic route afforded by pyruvate carboxylase to oxaloacetate formation, which resulted in accumulating 8.54 g/liter l-homoserine (0.33 g/g glucose, 62.4% of the maximum theoretical yield) in shake flask cultivation. Finally, a rationally designed strain gave 37.57 g/liter l-homoserine under fed-batch fermentation, with a yield of 0.31 g/g glucose. IMPORTANCE In this study, the bottlenecks that sequentially limit l-homoserine biosynthesis were identified and resolved, based on rational and efficient metabolic-engineering strategies, coupled with CRISPR interference (CRISPRi)-based systematic analysis. The metabolomics data largely expanded our understanding of metabolic effects and revealed relevant targets for further modification to achieve better performance. The systematic analysis strategy, as well as metabolomics analysis, can be used to rationally design cell factories for the production of highly valuable chemicals., (Copyright © 2020 Liu et al.)
- Published
- 2020
- Full Text
- View/download PDF
7. Enhanced production of L-methionine in engineered Escherichia coli with efficient supply of one carbon unit.
- Author
-
Tang XL, Du XY, Chen LJ, Liu ZQ, and Zheng YG
- Subjects
- Carbon metabolism, Carbon pharmacology, Escherichia coli genetics, Methionine genetics, Biosynthetic Pathways, Escherichia coli metabolism, Gene Expression Regulation, Bacterial, Metabolic Engineering, Methionine biosynthesis
- Abstract
Objective: L-methionine is an important sulfur-containing amino acid essential for humans and animals. Its biosynthesis pathway is complex and highly regulated. This study aims to explore the bottleneck limiting the improvement of L-methionine productivity and apply efficient strategies to increase L-methionine production in engineered E. coli., Results: The enzyme O-succinylhomoserine sulfhydrylase involved in thiolation of OSH to form homocysteine was overexpressed in the engineered strain E. coli W3110 IJAHFEBC/PAm, resulting in L-methionine production increased from 2.8 to 3.22 g/L in shake flask cultivation. By exogenous addition of L-glycine as the precursor of one carbon unit, the titer of L-methionine was increased to 3.68 g/L. The glycine cleavage system was further strengthened for the efficient one carbon unit supply and a L-methionine titer of 3.96 g/L was obtained, which was increased by 42% compared with that of the original strain., Conclusions: Insufficient supply of one carbon unit was found to be the issue limiting the improvement of L-methionine productivity and its up-regulation significantly promoted the L-methionine production in the engineered E. coli.
- Published
- 2020
- Full Text
- View/download PDF
8. Promoter engineering strategies for the overproduction of valuable metabolites in microbes.
- Author
-
Jin LQ, Jin WR, Ma ZC, Shen Q, Cai X, Liu ZQ, and Zheng YG
- Subjects
- Bacteria genetics, Biosensing Techniques methods, Biosynthetic Pathways genetics, Synthetic Biology methods, Yeasts genetics, Bioreactors microbiology, Gene Expression Regulation, Bacterial genetics, Metabolic Engineering methods, Promoter Regions, Genetic genetics, Transcription, Genetic genetics
- Abstract
Promoter engineering is an enabling technology in metabolic engineering and synthetic biology. As an indispensable part of synthetic biology, the promoter is a key factor in regulating genetic circuits and in coordinating multi-gene biosynthetic pathways. In this review, we summarized the recent progresses in promoter engineering in microbes. Specifically, the endogenous promoters are firstly discussed, followed by the statement of the influence of nucleotides exchange on the strength of promoters explored by site-selective mutagenesis. We then introduced the promoter libraries with a wide range of strength, which are constructed focusing on core promoter regions and upstream activating sequences by rational designs. Finally, the application of promoter libraries in the optimization of multi-gene metabolic pathways for high-yield production of metabolites was illustrated with a couple of recent examples.
- Published
- 2019
- Full Text
- View/download PDF
9. Metabolic engineering of Escherichia coli for d-pantothenic acid production.
- Author
-
Zhang B, Zhang XM, Wang W, Liu ZQ, and Zheng YG
- Subjects
- Alcohol Oxidoreductases genetics, Alcohol Oxidoreductases metabolism, Bacterial Proteins metabolism, Batch Cell Culture Techniques, Clustered Regularly Interspaced Short Palindromic Repeats genetics, Corynebacterium glutamicum genetics, Escherichia coli growth & development, Hydroxymethyl and Formyl Transferases genetics, Hydroxymethyl and Formyl Transferases metabolism, Mutagenesis, Pantothenic Acid chemistry, Transaminases genetics, Transaminases metabolism, Valine biosynthesis, Bacterial Proteins genetics, Escherichia coli metabolism, Metabolic Engineering, Pantothenic Acid biosynthesis
- Abstract
Escherichia coli was engineered to produce d-pantothenic acid via systematic metabolic engineering. Firstly, genes of acetohydroxy acid synthase II, pantothenate synthetase, 3-methyl-2-oxobutanoate hydroxymethyltransferase, 2-dehydropantoate 2-reductase and ketol-acid reductoisomerase were edited in E. coli W3110 with a resulting d-pantothenic acid yield of 0.49 g/L. Expressions of valine-pyruvate aminotransferase and branched-chain-amino-acid aminotransferase were then attenuated to decrease the carbon flux in l-valine biosynthetic pathway which is a competing pathway to the d-pantothenic acid biosynthetic pathway, and the yield increased to 1.48 g/L. Mutagenesis of pantothenate kinase and deletion of threonine deaminase further increased the production to 1.78 g/L. Overexpressions of panC and panB from Corynebacterium glutamicum enhanced the production by 29%. In fed-batch fermentations, strain DPA-9/pTrc99a-panBC(C.G) exhibited a highest d-pantothenic acid yield of 28.45 g/L. The findings in this study demonstrate the systematic metabolic engineering in Escherichia coli W3110 would be a promising strategy for industrial production of d-pantothenic acid., (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Published
- 2019
- Full Text
- View/download PDF
10. Fermentative production of the unnatural amino acid L-2-aminobutyric acid based on metabolic engineering.
- Author
-
Xu JM, Li JQ, Zhang B, Liu ZQ, and Zheng YG
- Subjects
- Bioreactors, Escherichia coli genetics, Metabolic Networks and Pathways, Threonine biosynthesis, Aminobutyrates metabolism, Escherichia coli metabolism, Fermentation, Metabolic Engineering
- Abstract
Background: L-2-aminobutyric acid (L-ABA) is an unnatural amino acid that is a key intermediate for the synthesis of several important pharmaceuticals. To make the biosynthesis of L-ABA environmental friendly and more suitable for the industrial-scale production. We expand the nature metabolic network of Escherichia coli using metabolic engineering approach for the production of L-ABA., Results: In this study, Escherichia coli THR strain with a modified pathway for threonine-hyperproduction was engineered via deletion of the rhtA gene from the chromosome. To redirect carbon flux from 2-ketobutyrate (2-KB) to L-ABA, the ilvIH gene was deleted to block the L-isoleucine pathway. Furthermore, the ilvA gene from Escherichia coli W3110 and the leuDH gene from Thermoactinomyces intermedius were amplified and co-overexpressed. The promoter was altered to regulate the expression strength of ilvA* and leuDH. The final engineered strain E. coli THR ΔrhtAΔilvIH/Gap-ilvA*-Pbs-leuDH was able to produce 9.33 g/L of L-ABA with a yield of 0.19 g/L/h by fed-batch fermentation in a 5 L bioreactor., Conclusions: This novel metabolically tailored strain offers a promising approach to fulfill industrial requirements for production of L-ABA.
- Published
- 2019
- Full Text
- View/download PDF
11. Enhanced diastereoselective synthesis of t-Butyl 6-cyano-(3R,5R)-dihydroxyhexanoate by using aldo-keto reductase and glucose dehydrogenase co-producing engineered Escherichia coli.
- Author
-
Wang YJ, Shen W, Luo X, Liu ZQ, and Zheng YG
- Subjects
- Aldo-Keto Reductases genetics, Bacterial Proteins genetics, Bacterial Proteins metabolism, Bioreactors, Caproates analysis, Caproates chemistry, Escherichia coli genetics, Glucose 1-Dehydrogenase genetics, Kluyveromyces enzymology, Kluyveromyces genetics, Recombinant Proteins genetics, Recombinant Proteins metabolism, Stereoisomerism, Aldo-Keto Reductases metabolism, Caproates metabolism, Escherichia coli metabolism, Glucose 1-Dehydrogenase metabolism, Metabolic Engineering methods
- Abstract
t-Butyl 6-cyano-(3R,5R)-dihydroxyhexanoate ((3R,5R)-2) is a key chiral diol precursor of atorvastatin calcium (Lipitor®). We have constructed a Kluyveromyces lactis aldo-keto reductase mutant KlAKR-Y295W/W296L (KlAKRm) by rational design in previous research, which displayed high activity and excellent diastereoselectivity (de
p > 99.5%) toward t-butyl 6-cyano-(5R)-hydroxy-3-oxohexanoate ((5R)-1). To realize in situ cofactor regeneration, a robust KlAKRm and Exiguobacterium sibiricum glucose dehydrogenase (EsGDH) co-producer E. coli BL 21(DE3) pETDuet-esgdh (MCS1)/pET-28b (+)-klakrm was constructed in this work. Under the optimized conditions, AKR and GDH activities of E. coli BL 21(DE3) pETDuet-esgdh (MCS1)/pET-28b (+)-klakrm peaked at 249.9 U/g DCW (dry cellular weight) and 29100 U/g DCW, respectively. It completely converted (5R)-1 at substrate loading size of up to 60.0 g/L (5R)-1 in the absence of exogenous NADH, which was one-fifth higher than that of the separately prepared KlAKRm and EsGDH under the same conditions. In this manner, a biocatalytic process for (3R,5R)-2 with productivity of 243.2 kg/m3 d was developed. Compared with the combination of separate expressed KlAKRm with EsGDH, co-expression of KlAKRm and EsGDH has the advantages of alleviating cell cultivation burden and elevating substrate load. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1235-1242, 2017., (© 2017 American Institute of Chemical Engineers.)- Published
- 2017
- Full Text
- View/download PDF
12. Metabolic engineering of Escherichia coli for microbial production of L-methionine.
- Author
-
Huang JF, Liu ZQ, Jin LQ, Tang XL, Shen ZY, Yin HH, and Zheng YG
- Subjects
- Batch Cell Culture Techniques, Bioreactors microbiology, Cloning, Molecular, Escherichia coli genetics, Fermentation, Gene Knockout Techniques, Lysine metabolism, Metabolic Networks and Pathways, Methionine analysis, Plasmids genetics, Threonine metabolism, Escherichia coli metabolism, Metabolic Engineering methods, Methionine metabolism
- Abstract
L-methionine has attracted a great deal of attention for its nutritional, pharmaceutical, and clinical applications. In this study, Escherichia coli W3110 was engineered via deletion of a negative transcriptional regulator MetJ and over-expression of homoserine O-succinyltransferase MetA together with efflux transporter YjeH, resulting in L-methionine overproduction which is up to 413.16 mg/L. The partial inactivation of the L-methionine import system MetD via disruption of metI made the engineered E. coli ΔmetJ ΔmetI/pTrcA*H more tolerant to high L-ethionine concentration and accumulated L-methionine to a level 43.65% higher than that of E. coli W3110 ΔmetJ/pTrcA*H. Furthermore, deletion of lysA, which blocks the lysine biosynthesis pathway, led to a further 8.5-fold increase in L-methionine titer of E. coli ΔmetJ ΔmetI ΔlysA/pTrcA*H. Finally, addition of Na
2 S2 O3 to the media led to an increase of fermentation titer of 11.45%. After optimization, constructed E. coli ΔmetJ ΔmetI ΔlysA/pTrcA*H was able to produce 9.75 g/L L-methionine with productivity of 0.20 g/L/h in a 5 L bioreactor. This novel metabolically tailored strain of E. coli provides an efficient platform for microbial production of L-methionine. Biotechnol. Bioeng. 2017;114: 843-851. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)- Published
- 2017
- Full Text
- View/download PDF
13. Upscale production of ethyl (S)-4-chloro-3-hydroxybutanoate by using carbonyl reductase coupled with glucose dehydrogenase in aqueous-organic solvent system.
- Author
-
Liu ZQ, Ye JJ, Shen ZY, Hong HB, Yan JB, Lin Y, Chen ZX, Zheng YG, and Shen YC
- Subjects
- Alcohol Oxidoreductases genetics, Escherichia coli genetics, Escherichia coli growth & development, Glucose 1-Dehydrogenase genetics, Molecular Sequence Data, Recombinant Proteins genetics, Recombinant Proteins metabolism, Sequence Analysis, DNA, Alcohol Oxidoreductases metabolism, Butyrates metabolism, Escherichia coli metabolism, Glucose 1-Dehydrogenase metabolism, Metabolic Engineering, Solvents
- Abstract
(S)-4-chloro-3-hydroxybutanoate ((S)-CHBE) is an important chiral intermediate to synthesize the side chain of cholesterol-lowering drug atorvastatin. To biosynthesize the (S)-CHBE, a recombinant Escherichia coli harboring the carbonyl reductase and glucose dehydrogenase was successfully constructed. The recombinant E. coli was cultured in a 500-L fermentor; after induction and expression, the enzyme activity and cell biomass were increased to 23,661.65 U/L and 13.90 g DCW/L which was 3.24 and 2.60-folds compared with those in the 50 L fermentor. The biocatalytic process for the synthesis of (S)-CHBE in an aqueous-organic solvent system was constructed and optimized with a substrate fed-batch strategy. The ethyl 4-chloro-3-oxobutanoate concentration reached to 1.7 M, and the (S)-CHBE with yield of 97.2 % and enantiomeric excess (e.e.) of 99 % was obtained after 4-h reaction in a 50-L reactor. In this study, the space-time yield and space-time yield per gram of biomass (dry cell weight, DCW) were 413.17 mM/h and 27.55 mM/h/g DCW for (S)-CHBE production, respectively, which were the highest values as compared to previous reports. Finally, (S)-CHBE was extracted from the reaction mixture with 82 % of yield and 95 % of purity. This study paved the foundation for the upscale production of (S)-CHBE by biocatalysis method.
- Published
- 2015
- Full Text
- View/download PDF
14. Metabolic engineering and pathway construction for O-acetyl-L-homoserine production in Escherichia coli
- Author
-
Li, Bo, Huang, Liang-Gang, Yang, Yu-Feng, Chen, Yuan-Yuan, Zhou, Xiao-Jie, Liu, Zhi-Qiang, and Zheng, Yu-Guo
- Published
- 2023
- Full Text
- View/download PDF
15. Thorough research and modification of one-carbon units cycle for improving L-methionine production in Escherichia coli
- Author
-
Shen, Zhen-Yang, Wang, Yi-Feng, Wang, Li-Juan, Wang, Ying, Liu, Zhi-Qiang, and Zheng, Yu-Guo
- Published
- 2023
- Full Text
- View/download PDF
16. Metabolic engineering of E. coli for the production of O-succinyl-l-homoserine with high yield
- Author
-
Huang, Jian-Feng, Zhang, Bo, Shen, Zhen-Yang, Liu, Zhi-Qiang, and Zheng, Yu-Guo
- Published
- 2018
- Full Text
- View/download PDF
17. Local metabolic response of Escherichia coli to the module genetic perturbations in l-methionine biosynthetic pathway.
- Author
-
Shen, Zhen-Yang, Wang, Yi-Feng, Wang, Li-Juan, Wang, Ying, Liu, Zhi-Qiang, and Zheng, Yu-Guo
- Subjects
- *
METHIONINE , *ESCHERICHIA coli , *BIOSYNTHESIS , *CYSTEINE - Abstract
l -Methionine biosynthesis is through multilevel regulated and multibranched biosynthetic pathway (MRMBP). Because of the complex regulatory mechanism and the imbalanced metabolic flux between branched pathways, microbial production of l -methionine has not been commercialized. In this study, local metabolic response in MRMBP of l -methionine was investigated and various crucial genes in branched pathways were determined. In l -serine pathway, the crucial gene was serABC. In O -succinyl homoserine (OSH) pathway, which was the C4 backbone of l -methionine, metB and metL controlled the metabolic flux jointly. In l -cysteine pathway, the crucial gene cysE fbr could disturb the flux distribution of local network in l -methionine biosynthesis. However, no crucial gene for l -methionine production in 5-methyl tetrahydrofolate (CH 3 -THF) pathway was found. The relation between these pathways was also researched. l -Serine pathway, as the upstream pathway of l -cysteine and CH 3 -THF, played a crucial role in l -methionine biosynthesis. l -Cysteine pathway showed the strongest controlling force of the metabolic flux, and OSH pathway was second to l -cysteine pathway. In contrast, CH 3 -THF pathway was the weakest, which was probably the mainly limited steps at present and had great potential in further research. In addition, constructed W3110 IJAHFEBC/pA∗HAmL was able to produce 2.62 g/L l -methionine in flask. This study is instructive for l -methionine biosynthesis and provides a new research method of biosynthesizing other metabolic products in MRMBPs. [Display omitted] • Multilevel regulated and multibranched biosynthetic pathways (MRMBPs) for l -methionine biosynthesis were analyzed. • Various crucial genes in MRMBPs for l -methionine biosynthesis were determined. • The balance between MRMBPs for l -methionine biosynthesis was clarified. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. Re-designing Escherichia coli for high-yield production of β-alanine by metabolic engineering.
- Author
-
Zhou, Hai-Yan, Tang, Ya-Qun, Peng, Jin-Bang, Wang, Shuang-Hui, Liu, Zhi-Qiang, and Zheng, Yu-Guo
- Subjects
- *
PANTOTHENIC acid , *PYRUVATES , *ESCHERICHIA coli , *SUCCINIC acid , *ENGINEERING - Abstract
β-Alanine is the only natural β-amino acid and an important precursor for pantothenic acid (vitamin B 5) synthesis. In this work, to improve the β-alanine fermentative production, collaborative modifications mainly focused on aspartate ammonia-lyase (aspA), phosphoenolpyruvate (PEP) – pyruvate (PYR) – oxaloacetate (OAA) – L -aspartate nodes, glucose uptake system, and β-alanine uptake system were performed, including knock out of aspA , reducing the consumption of central metabolic nodes PEP and PYR, enforcement of the non-PEP-dependent transferase system (non-PTS), inactivation of gluconeogenesis through deleting pck gene, and disruption of β-alanine uptake system. As a result, a significantly enhanced β-alanine accumulation was achieved. The β-alanine titer was increased to 6.67 g/L (final strain B15) from 2.46 g/L (original strain B1) in shake flask fermentation, and a titer of 41.12 g/L was achieved in 5-L fermentor fermentation. With the presence of succinic acid (0.25 g/L), the β-alanine titer eventually reached 52.61 g/L at 72 h, and a high productivity (0.73 g/L/h) and yield (0.268 g/g glucose) were also obtained. The yield was relatively higher compared with the reported levels and the B15 exhibited a remarkable fermentation stability over a long period. This result laid foundation for industrialization of β-alanine fermentative production. [Display omitted] • Deletion of aspA gene improved the β-alanine biosynthesis (34.15 %). • Knocking out gene dadx resulted in a nearly 10 % increased β-alanine titer. • Knocking out gene pck resulted in 45.89 % increased β-alanine titer. • Addition of succinic acid (0.25 g/L) could improve β-alanine production. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.