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Islam T, Nguyen-Vo TP, Gaur VK, Lee J, Park S. Metabolic engineering of Escherichia coli for biological production of 1, 3-Butanediol. BIORESOURCE TECHNOLOGY 2023; 376:128911. [PMID: 36934906 DOI: 10.1016/j.biortech.2023.128911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/08/2023] [Accepted: 03/14/2023] [Indexed: 06/18/2023]
Abstract
The production of 1,3-butanediol (1,3-BDO) from glucose was investigated using Escherichia coli as the host organism. A pathway was engineered by overexpressing genes phaA (acetyl-CoA acetyltransferase), phaB (acetoacetyl-CoA reductase), bld (CoA-acylating aldehyde dehydrogenase), and yqhD (alcohol dehydrogenase). The expression levels of these genes were optimized to improve 1,3-BDO production and pathways that compete with 1,3-BDO synthesis were disrupted. Culture conditions were also optimized, including the C: N ratio, aeration, induction time, temperature, and supplementation of amino acids, resulting in a strain that could produce 1,3-BDO at 257 mM in 36 h, with a yield of 0.51 mol/mol in a fed-batch bioreactor experiment. To the best of our knowledge, this is the highest titer of 1,3-BDO production ever reported using biological methods, and our findings provide a promising strategy for the development of microbial cell factories for the sustainable synthesis of other acetyl-CoA-derived chemicals.
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Affiliation(s)
- Tayyab Islam
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Thuan Phu Nguyen-Vo
- Department of Chemical and Biochemical Engineering, North Carolina State University, Raleigh, NC 27606, USA
| | - Vivek Kumar Gaur
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Junhak Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea; R&D Center, ACTIVON Co., Ltd., Cheongju 28104, Republic of Korea
| | - Sunghoon Park
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
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2
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Ding Z, Kumar Awasthi S, Kumar M, Kumar V, Mikhailovich Dregulo A, Yadav V, Sindhu R, Binod P, Sarsaiya S, Pandey A, Taherzadeh MJ, Rathour R, Singh L, Zhang Z, Lian Z, Kumar Awasthi M. A thermo-chemical and biotechnological approaches for bamboo waste recycling and conversion to value added product: Towards a zero-waste biorefinery and circular bioeconomy. FUEL 2023; 333:126469. [DOI: 10.1016/j.fuel.2022.126469] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
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3
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Menacho-Melgar R, Lynch MD. Simple Scalable Protein Expression and Extraction Using Two-stage Autoinducible Cell Autolysis and DNA/RNA Autohydrolysis in Escherichia coli. Bio Protoc 2022; 12:e4297. [PMID: 35127987 PMCID: PMC8799905 DOI: 10.21769/bioprotoc.4297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/10/2021] [Accepted: 11/15/2021] [Indexed: 12/01/2023] Open
Abstract
Recombinant protein expression is extensively used in biological research. Despite this, current protein expression and extraction methods are not readily scalable or amenable for high-throughput applications. Optimization of protein expression conditions using traditional methods, reliant on growth-associated induction, is non-trivial. Similarly, protein extraction methods are predominantly restricted to chemical methods, and mechanical methods reliant on expensive specialized equipment more tuned for large-scale applications. In this article, we outline detailed protocols for the use of an engineered autolysis/autohydrolysis E. coli strain, in two-stage fermentations in shake-flasks. This two-stage fermentation protocol does not require optimization of expression conditions and results in high protein titers. Cell lysis in an engineered strain is tightly controlled and only triggered post-culture by addition of a 0.1% detergent solution. Upon cell lysis, a nuclease digests contaminating host oligonucleotides, which facilitates sample handling. This method has been validated for use at different scales, from microtiter plates to instrumented bioreactors. Graphic abstract: Two-stage protein expression, cell autolysis and DNA/RNA autohydrolysis. Reprinted with permission from Menacho-Melgar et al. (2020a). Copyright 2020 John Wiley and Sons.
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Affiliation(s)
| | - Michael D. Lynch
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Biosynthesis of Poly-(3-hydroxybutyrate) under the Control of an Anaerobically Induced Promoter by Recombinant Escherichia coli from Sucrose. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27010294. [PMID: 35011525 PMCID: PMC8746831 DOI: 10.3390/molecules27010294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 12/28/2021] [Accepted: 12/31/2021] [Indexed: 12/05/2022]
Abstract
Poly-(3-hydroxybutyrate) (PHB) is a polyester with biodegradable and biocompatible characteristics and has many potential applications. To reduce the raw material costs and microbial energy consumption during PHB production, cheaper carbon sources such as sucrose were evaluated for the synthesis of PHB under anaerobic conditions. In this study, metabolic network analysis was conducted to construct an optimized pathway for PHB production using sucrose as the sole carbon source and to guide the gene knockout to reduce the generation of mixed acid byproducts. The plasmid pMCS-sacC was constructed to utilize sucrose as a sole carbon source, and the cascaded promoter P3nirB was used to enhance PHB synthesis under anaerobic conditions. The mixed acid fermentation pathway was knocked out in Escherichia coli S17-1 to reduce the synthesis of byproducts. As a result, PHB yield was improved to 80% in 6.21 g/L cell dry weight by the resulted recombinant Escherichia coli in a 5 L bed fermentation, using sucrose as the sole carbon source under anaerobic conditions. As a result, the production costs of PHB will be significantly reduced.
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Menacho-Melgar R, Hennigan JN, Lynch MD. Optimization of phosphate-limited autoinduction broth for two-stage heterologous protein expression in Escherichia coli. Biotechniques 2021; 71:566-572. [PMID: 34431325 DOI: 10.2144/btn-2021-0055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Autoinducible, two-stage protein expression leveraging phosphate-inducible promoters has been recently shown to enable not only high protein titers but also consistent performance across scales from screening systems (microtiter plates) to instrumented bioreactors. However, to date, small-scale production using microtiter plates and shake flasks relies on a complex autoinduction broth (AB) that requires making numerous media components, not all amenable to autoclaving. In this report, the authors develop a simpler media formulation (AB-2) with just a few autoclavable components. AB-2 is robust to small changes in its composition and performs equally, if not better, than AB across different scales. AB-2 will facilitate the adoption of phosphate-limited two-stage protein expression protocols.
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Affiliation(s)
| | | | - Michael D Lynch
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Choi SY, Cho IJ, Lee Y, Kim YJ, Kim KJ, Lee SY. Microbial Polyhydroxyalkanoates and Nonnatural Polyesters. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907138. [PMID: 32249983 DOI: 10.1002/adma.201907138] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/20/2020] [Indexed: 06/11/2023]
Abstract
Microorganisms produce diverse polymers for various purposes such as storing genetic information, energy, and reducing power, and serving as structural materials and scaffolds. Among these polymers, polyhydroxyalkanoates (PHAs) are microbial polyesters synthesized and accumulated intracellularly as a storage material of carbon, energy, and reducing power under unfavorable growth conditions in the presence of excess carbon source. PHAs have attracted considerable attention for their wide range of applications in industrial and medical fields. Since the first discovery of PHA accumulating bacteria about 100 years ago, remarkable advances have been made in the understanding of PHA biosynthesis and metabolic engineering of microorganisms toward developing efficient PHA producers. Recently, nonnatural polyesters have also been synthesized by metabolically engineered microorganisms, which opened a new avenue toward sustainable production of more diverse plastics. Herein, the current state of PHAs and nonnatural polyesters is reviewed, covering mechanisms of microbial polyester biosynthesis, metabolic pathways, and enzymes involved in biosynthesis of short-chain-length PHAs, medium-chain-length PHAs, and nonnatural polyesters, especially 2-hydroxyacid-containing polyesters, metabolic engineering strategies to produce novel polymers and enhance production capabilities and fermentation, and downstream processing strategies for cost-effective production of these microbial polyesters. In addition, the applications of PHAs and prospects are discussed.
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Affiliation(s)
- So Young Choi
- Metabolic and Biomolecular Engineering National Research Laboratory, Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - In Jin Cho
- Metabolic and Biomolecular Engineering National Research Laboratory, Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Youngjoon Lee
- Metabolic and Biomolecular Engineering National Research Laboratory, Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Yeo-Jin Kim
- School of Life Sciences (KNU Creative BioResearch Group), KNU Institute for Microorganisms, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566, Republic of Korea
| | - Kyung-Jin Kim
- School of Life Sciences (KNU Creative BioResearch Group), KNU Institute for Microorganisms, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566, Republic of Korea
| | - Sang Yup Lee
- Metabolic and Biomolecular Engineering National Research Laboratory, Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
- BioProcess Engineering Research Center and Bioinformatics Research Center, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
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Menacho-Melgar R, Ye Z, Moreb EA, Yang T, Efromson JP, Decker JS, Wang R, Lynch MD. Scalable, two-stage, autoinduction of recombinant protein expression in E. coli utilizing phosphate depletion. Biotechnol Bioeng 2020; 117:2715-2727. [PMID: 32441815 DOI: 10.1002/bit.27440] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 12/24/2022]
Abstract
We report the scalable production of recombinant proteins in Escherichia coli, reliant on tightly controlled autoinduction, triggered by phosphate depletion in the stationary phase. The method, reliant on engineered strains and plasmids, enables improved protein expression across scales. Expression levels using this approach have reached as high as 55% of the total cellular protein. The initial use of the method in instrumented fed-batch fermentations enables cell densities of ∼30 gCDW/L and protein titers up to 8.1 ± 0.7 g/L (∼270 mg/gCDW). The process has also been adapted to an optimized autoinduction media, enabling routine batch production at culture volumes of 20 μl (384-well plates), 100 μl (96-well plates), 20 ml, and 100 ml. In batch cultures, cell densities routinely reach ∼5-7 gCDW/L, offering protein titers above 2 g/L. The methodology has been validated with a set of diverse heterologous proteins and is of general use for the facile optimization of routine protein expression from high throughput screens to fed-batch fermentation.
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Affiliation(s)
| | - Zhixia Ye
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Eirik A Moreb
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Tian Yang
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - John P Efromson
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - John S Decker
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Ruixin Wang
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Michael D Lynch
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
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Ku JT, Chen AY, Lan EI. Metabolic Engineering Design Strategies for Increasing Acetyl-CoA Flux. Metabolites 2020; 10:metabo10040166. [PMID: 32340392 PMCID: PMC7240943 DOI: 10.3390/metabo10040166] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/19/2020] [Accepted: 04/21/2020] [Indexed: 01/18/2023] Open
Abstract
Acetyl-CoA is a key metabolite precursor for the biosynthesis of lipids, polyketides, isoprenoids, amino acids, and numerous other bioproducts which are used in various industries. Metabolic engineering efforts aim to increase carbon flux towards acetyl-CoA in order to achieve higher productivities of its downstream products. In this review, we summarize the strategies that have been implemented for increasing acetyl-CoA flux and concentration, and discuss their effects. Furthermore, recent works have developed synthetic acetyl-CoA biosynthesis routes that achieve higher stoichiometric yield of acetyl-CoA from glycolytic substrates.
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Affiliation(s)
- Jason T. Ku
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu City 300, Taiwan; (J.T.K.); (A.Y.C.)
| | - Arvin Y. Chen
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu City 300, Taiwan; (J.T.K.); (A.Y.C.)
| | - Ethan I. Lan
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu City 300, Taiwan
- Correspondence:
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Yang J, Ye R, Zhang H, Liu Y. Amplification of lmbB1 gene in Streptomyces lincolnensis improves quantity and quality of lincomycin A fermentation. Prep Biochem Biotechnol 2020; 50:529-537. [PMID: 31916478 DOI: 10.1080/10826068.2019.1710714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
As a lincosamide antibiotic, lincomycin is still important for treating diseases caused by Gram-positive bacteria. Manufacturing of lincomycin needs efforts to, e.g. maximize desirable species and minimizing unwanted fermentation byproducts. Analysis of the lincomycin biosynthetic gene cluster of Streptomyces lincolnensis, lmbB1, was shown to catalyze the conversion of L-dopa but not of L-tyrosine and then further generated the precursor of lincomycin A. Based on the principle of directed breeding, a strain termed as S. lincolnensis 24-2, was obtained in this work. By overexpressing the lmbB1 gene, this strain produces efficacious lincomycin A and suppresses melanin generation, whereas contains unwanted lincomycin B. The good fermentation performance of the mutant-lmbB1 (M-lmbB1) was also confirmed in a 15 L-scale bioreactor, which increased the lincomycin A production by 37.6% compared with control of 6435 u/mL and reduced the accumulation of melanin by 29.9% and lincomycin B by 73.4%. This work demonstrated that the amplification of lmbB1 gene mutation and metabolic engineering could promote lincomycin biosynthesis and might be helpful for reducing the production of other industrially unnecessary byproduct.
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Affiliation(s)
- Jing Yang
- The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Ruifang Ye
- The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | | | - Yan Liu
- Topfond Pharmaceutical Co., Ltd, Henan, China
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10
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Kumar G, Ponnusamy VK, Bhosale RR, Shobana S, Yoon JJ, Bhatia SK, Rajesh Banu J, Kim SH. A review on the conversion of volatile fatty acids to polyhydroxyalkanoates using dark fermentative effluents from hydrogen production. BIORESOURCE TECHNOLOGY 2019; 287:121427. [PMID: 31104939 DOI: 10.1016/j.biortech.2019.121427] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 05/03/2019] [Accepted: 05/04/2019] [Indexed: 06/09/2023]
Abstract
The production of bio/microbial-based polymers, polyhydroxyalkanoates (PHAs) from volatile fatty acids (VFAs) of dark fermentative effluents in the bio-H2 reactor is being paid attention, owing to their commercial demand, applications and as carbon as well as energy storage source. Since, they are the cheap precursors for such valuable renewable biopolymers which all possess the properties; those are analogous to the petro-derived plastics. Several studies were stated, related to the consumption of both individual and mixed VFAs for the potential PHAs production. Their biodegradability nature makes them extremely desirable alternative to fossil-derived synthetic polymers. In this regard, this review summarizes the use of bio-based PHAs production via both microbial and biochemical pathways using dark fermentative bio-H2 production from waste streams as feedstock. Furthermore, this review deals the characteristics, synthesis and production of the bio-based PHAs along with their co-polymers and applications to give an outlook on future research.
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Affiliation(s)
- Gopalakrishnan Kumar
- Institute of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, Box 8600 Forus, 4036 Stavanger, Norway; School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Vinoth Kumar Ponnusamy
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung City 807, Taiwan; Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung City 807, Taiwan
| | - Rahul R Bhosale
- Department of Chemical Engineering, College of Engineering, Qatar University, P.O Box 2713, Doha, Qatar
| | - Sutha Shobana
- Department of Chemistry and Research Centre, Aditanar College of Arts and Science, Virapandianpatnam, Tiruchendur, Tamil Nadu, India
| | - Jeong-Jun Yoon
- Intelligent Sustainable Materials R&BD Group, Korea Institute of Industrial Technology (KITECH), Cheonan, Chungnam 31056, Republic of Korea
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University, Seoul, Republic of Korea
| | - J Rajesh Banu
- Department of Civil Engineering, Anna University Regional Campus, Tirunelveli, India
| | - Sang-Hyoun Kim
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea.
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Metabolism of sucrose in a non-fermentative Escherichia coli under oxygen limitation. Appl Microbiol Biotechnol 2019; 103:6245-6256. [PMID: 31147757 PMCID: PMC6616217 DOI: 10.1007/s00253-019-09909-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 05/10/2019] [Accepted: 05/11/2019] [Indexed: 01/21/2023]
Abstract
Biotechnological industry strives to develop anaerobic bioprocesses fueled by abundant and cheap carbon sources, like sucrose. However, oxygen-limiting conditions often lead to by-product formation and reduced ATP yields. While by-product formation is typically decreased by gene deletion, the breakdown of oligosaccharides with inorganic phosphate instead of water could increment the ATP yield. To observe the effect of oxygen limitation during sucrose consumption, a non-fermentative Escherichia coli K-12 strain was transformed with genes enabling sucrose assimilation. It was observed that the combined deletion of the genes adhE, adhP, mhpF, ldhA, and pta abolished the anaerobic growth using sucrose. Therefore, the biomass-specific conversion rates were obtained using oxygen-limited continuous cultures. Strains performing the breakdown of the sucrose by hydrolysis (SUC-HYD) or phosphorolysis (SUC-PHOSP) were studied in such conditions. An experimentally validated in silico model, modified to account for plasmid and protein burdens, was employed to calculate carbon and electron consistent conversion rates. In both strains, the biomass yields were lower than expected and, strikingly, SUC-PHOSP showed a yield lower than SUC-HYD. Flux balance analyses indicated a significant increase in the non-growth-associated ATP expenses by comparison with the growth on glucose. The observed fructose-1,6-biphosphatase and phosphoglucomutase activities, as well as the concentrations of glycogen, suggest the operation of ATP futile cycles triggered by a combination of the oxygen limitation and the metabolites released during the sucrose breakdown.
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Perez-Zabaleta M, Guevara-Martínez M, Gustavsson M, Quillaguamán J, Larsson G, van Maris AJA. Comparison of engineered Escherichia coli AF1000 and BL21 strains for (R)-3-hydroxybutyrate production in fed-batch cultivation. Appl Microbiol Biotechnol 2019; 103:5627-5639. [PMID: 31104101 PMCID: PMC6597613 DOI: 10.1007/s00253-019-09876-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 04/18/2019] [Accepted: 04/24/2019] [Indexed: 02/06/2023]
Abstract
Accumulation of acetate is a limiting factor in recombinant production of (R)-3-hydroxybutyrate (3HB) by Escherichia coli in high-cell-density processes. To alleviate this limitation, this study investigated two approaches: (i) deletion of phosphotransacetylase (pta), pyruvate oxidase (poxB), and/or the isocitrate lyase regulator (iclR), known to decrease acetate formation, on bioreactor cultivations designed to achieve high 3HB concentrations. (ii) Screening of different E. coli strain backgrounds (B, BL21, W, BW25113, MG1655, W3110, and AF1000) for their potential as low acetate-forming, 3HB-producing platforms. Deletion of pta and pta-poxB in the AF1000 strain background was to some extent successful in decreasing acetate formation, but also dramatically increased excretion of pyruvate and did not result in increased 3HB production in high-cell-density fed-batch cultivations. Screening of the different E. coli strains confirmed BL21 as a low acetate-forming background. Despite low 3HB titers in low-cell-density screening, 3HB-producing BL21 produced five times less acetic acid per mole of 3HB, which translated into a 2.3-fold increase in the final 3HB titer and a 3-fold higher volumetric 3HB productivity over 3HB-producing AF1000 strains in nitrogen-limited fed-batch cultivations. Consequently, the BL21 strain achieved the hitherto highest described volumetric productivity of 3HB (1.52 g L−1 h−1) and the highest 3HB concentration (16.3 g L−1) achieved by recombinant E. coli. Screening solely for 3HB titers in low-cell-density batch cultivations would not have identified the potential of this strain, reaffirming the importance of screening with the final production conditions in mind.
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Affiliation(s)
- Mariel Perez-Zabaleta
- School of Engineering Sciences in Chemistry, Biotechnology, and Health (CBH), Department of Industrial Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Center of Biotechnology, Faculty of Science and Technology, Universidad Mayor de San Simón, Cochabamba, Bolivia
| | - Mónica Guevara-Martínez
- School of Engineering Sciences in Chemistry, Biotechnology, and Health (CBH), Department of Industrial Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Center of Biotechnology, Faculty of Science and Technology, Universidad Mayor de San Simón, Cochabamba, Bolivia
| | - Martin Gustavsson
- School of Engineering Sciences in Chemistry, Biotechnology, and Health (CBH), Department of Industrial Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - Jorge Quillaguamán
- Center of Biotechnology, Faculty of Science and Technology, Universidad Mayor de San Simón, Cochabamba, Bolivia
| | - Gen Larsson
- School of Engineering Sciences in Chemistry, Biotechnology, and Health (CBH), Department of Industrial Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - Antonius J. A. van Maris
- School of Engineering Sciences in Chemistry, Biotechnology, and Health (CBH), Department of Industrial Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691 Stockholm, Sweden
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Jung HR, Yang SY, Moon YM, Choi TR, Song HS, Bhatia SK, Gurav R, Kim EJ, Kim BG, Yang YH. Construction of Efficient Platform Escherichia coli Strains for Polyhydroxyalkanoate Production by Engineering Branched Pathway. Polymers (Basel) 2019; 11:polym11030509. [PMID: 30960493 PMCID: PMC6473851 DOI: 10.3390/polym11030509] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/05/2019] [Accepted: 03/11/2019] [Indexed: 02/07/2023] Open
Abstract
Polyhydroxyalkanoate (PHA) is a potential substitute for petroleum-based plastics and can be produced by many microorganisms, including recombinant Escherichia coli. For efficient conversion of substrates and maximum PHA production, we performed multiple engineering of branched pathways in E. coli. We deleted four genes (pflb, ldhA, adhE, and fnr), which contributed to the formation of byproducts, using the CRISPR/Cas9 system and overexpressed pntAB, which catalyzes the interconversion of NADH and NADPH. The constructed strain, HR002, showed accumulation of acetyl-CoA and decreased levels of byproducts, resulting in dramatic increases in cell growth and PHA content. Thus, we demonstrated the effects of multiple engineering for redirecting carbon flux into PHA production without any concerns regarding simultaneous deletion.
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Affiliation(s)
- Hye-Rim Jung
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Su-Yeon Yang
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Yu-Mi Moon
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Tae-Rim Choi
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Hun-Suk Song
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
- Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, Seoul 05029, Korea.
| | - Ranjit Gurav
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
| | - Eun-Jung Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea.
| | - Byung-Gee Kim
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul 08826, Korea.
- School of Chemical and Biological Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.
| | - Yung-Hun Yang
- Department of Biological Engineering, College of Engineering, Konkuk University, 120, Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea.
- Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, Seoul 05029, Korea.
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14
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Iterative genome editing of Escherichia coli for 3-hydroxypropionic acid production. Metab Eng 2018; 47:303-313. [DOI: 10.1016/j.ymben.2018.04.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/09/2018] [Accepted: 04/11/2018] [Indexed: 11/21/2022]
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15
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Tarasava K, Liu R, Garst A, Gill RT. Combinatorial pathway engineering using type I-E CRISPR interference. Biotechnol Bioeng 2018. [PMID: 29537074 DOI: 10.1002/bit.26589] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Optimization of metabolic flux is a difficult and time-consuming process that often involves changing the expression levels of multiple genes simultaneously. While some pathways have a known rate limiting step, more complex metabolic networks can require a trial-and-error approach of tuning the expression of multiple genes to achieve a desired distribution of metabolic resources. Here we present an efficient method for generating expression diversity on a combinatorial scale using CRISPR interference. We use a modified native Escherichia coli Type I-E CRISPR-Cas system and an iterative cloning strategy for construction of guide RNA arrays. This approach allowed us to build a combinatorial gene expression library three orders of magnitude larger than previous studies. In less than 1 month, we generated ∼12,000 combinatorial gene expression variants that target six different genes and screened these variants for increased malonyl-CoA flux and 3-hydroxypropionate (3HP) production. We were able to identify a set of variants that exhibited a significant increase in malonyl-CoA flux and up to a 98% increase in 3HP production. This approach provides a fast and easy-to-implement strategy for engineering metabolic pathway flux for development of industrially relevant strains, as well as investigation of fundamental biological questions.
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Affiliation(s)
- Katia Tarasava
- Chemical and Biological Engineering Department, University of Colorado Boulder, Boulder, Colorado
| | - Rongming Liu
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado
| | | | - Ryan T Gill
- Chemical and Biological Engineering Department, University of Colorado Boulder, Boulder, Colorado.,Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, Boulder, Colorado
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16
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Matsumoto T, Tanaka T, Kondo A. Engineering metabolic pathways in Escherichia coli for constructing a "microbial chassis" for biochemical production. BIORESOURCE TECHNOLOGY 2017; 245:1362-1368. [PMID: 28522199 DOI: 10.1016/j.biortech.2017.05.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/28/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
The present work reviews literature describing the re-design of the metabolic pathways of a microbial host using sophisticated genetic tools, yielding strains for producing value-added chemicals including fuels, building-block chemicals, pharmaceuticals, and derivatives. This work employed Escherichia coli, a well-studied microorganism that has been successfully engineered to produce various chemicals. E. coli has several advantages compared with other microorganisms, including robustness, and handling. To achieve efficient productivities of target compounds, an engineered E. coli should accumulate metabolic precursors of target compounds. Multiple researchers have reported the use of pathway engineering to generate strains capable of accumulating various metabolic precursors, including pyruvate, acetyl-CoA, malonyl-CoA, mevalonate and shikimate. The aim of this review provides a promising guideline for designing E. coli strains capable of producing a variety of useful chemicals. Herein, the present work reviews their common and unique strategies, treating metabolically engineered E. coli as a "microbial chassis".
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Affiliation(s)
- Takuya Matsumoto
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan
| | - Tsutomu Tanaka
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan
| | - Akihiko Kondo
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan; Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan.
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17
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Zheng Y, Yuan Q, Yang X, Ma H. Engineering Escherichia coli for poly-(3-hydroxybutyrate) production guided by genome-scale metabolic network analysis. Enzyme Microb Technol 2017; 106:60-66. [PMID: 28859811 DOI: 10.1016/j.enzmictec.2017.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/22/2017] [Accepted: 07/07/2017] [Indexed: 11/16/2022]
Abstract
Poly-(3-hydroxybutyrate) (P3HB) is a promising biodegradable plastic synthesized from acetyl-CoA. One important factor affecting the P3HB production cost is the P3HB yield. Through flux balance analysis of an extended genome-scale metabolic network of E. coli, we found that the introduction of non-oxidative glycolysis pathway (NOG), a previously reported pathway enabling complete carbon conservation, can increase the theoretical carbon yield from 67% to 89%, equivalent to the theoretical mass yield from 0.48g P3HB/g glucose to 0.64g P3HB/g glucose. Based on this analysis result, we introduced phosphoketolase and enhanced the NOG pathway in E. coli. The mass yield in the engineered strain was increased from 0.16g P3HB/g glucose to 0.24g P3HB/g glucose. We further overexpressed pntAB to enhance the NADPH availability and down-regulated TCA cycle to divert more acetyl-CoA toward P3HB. The final construct accumulated 5.7g/L P3HB and reached a carbon yield of 0.43 (a mass yield of 0.31g P3HB/g glucose) in shake flask cultures in shake flask cultures. The introduction of NOG pathway could also be useful for improving yields of many other biochemicals derived from acetyl-coA.
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Affiliation(s)
- Yangyang Zheng
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qianqian Yuan
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Xiaoyan Yang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China; Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Hongwu Ma
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
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18
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Enjalbert B, Millard P, Dinclaux M, Portais JC, Létisse F. Acetate fluxes in Escherichia coli are determined by the thermodynamic control of the Pta-AckA pathway. Sci Rep 2017; 7:42135. [PMID: 28186174 PMCID: PMC5301487 DOI: 10.1038/srep42135] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/28/2016] [Indexed: 12/30/2022] Open
Abstract
Escherichia coli excretes acetate upon growth on fermentable sugars, but the regulation of this production remains elusive. Acetate excretion on excess glucose is thought to be an irreversible process. However, dynamic 13C-metabolic flux analysis revealed a strong bidirectional exchange of acetate between E. coli and its environment. The Pta-AckA pathway was found to be central for both flux directions, while alternative routes (Acs or PoxB) play virtually no role in glucose consumption. Kinetic modelling of the Pta-AckA pathway predicted that its flux is thermodynamically controlled by the extracellular acetate concentration in vivo. Experimental validations confirmed that acetate production can be reduced and even reversed depending solely on its extracellular concentration. Consistently, the Pta-AckA pathway can rapidly switch from acetate production to consumption. Contrary to current knowledge, E. coli is thus able to co-consume glucose and acetate under glucose excess. These metabolic capabilities were confirmed on other glycolytic substrates which support the growth of E. coli in the gut. These findings highlight the dual role of the Pta-AckA pathway in acetate production and consumption during growth on glycolytic substrates, uncover a novel regulatory mechanism that controls its flux in vivo, and significantly expand the metabolic capabilities of E. coli.
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Affiliation(s)
- Brice Enjalbert
- LISBP, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
| | - Pierre Millard
- LISBP, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
| | - Mickael Dinclaux
- LISBP, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
| | | | - Fabien Létisse
- LISBP, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
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19
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Li H, Ye R, Lin G, Zhu D, Mao Q. Protein expression analysis of a high-demeclocycline producing strain of Streptomyces aureofaciens and the roles of CtcH and CtcJ in demeclocycline biosynthesis. BIORESOUR BIOPROCESS 2016. [DOI: 10.1186/s40643-016-0123-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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20
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Anjum A, Zuber M, Zia KM, Noreen A, Anjum MN, Tabasum S. Microbial production of polyhydroxyalkanoates (PHAs) and its copolymers: A review of recent advancements. Int J Biol Macromol 2016; 89:161-74. [PMID: 27126172 DOI: 10.1016/j.ijbiomac.2016.04.069] [Citation(s) in RCA: 292] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/15/2016] [Accepted: 04/22/2016] [Indexed: 02/02/2023]
Abstract
Traditional mineral oil based plastics are important commodity to enhance the comfort and quality of life but the accumulation of these plastics in the environment has become a major universal problem due to their low biodegradation. Solution to the plastic waste management includes incineration, recycling and landfill disposal methods. These processes are very time consuming and expensive. Biopolymers are important alternatives to the petroleum-based plastics due to environment friendly manufacturing processes, biodegradability and biocompatibility. Therefore use of novel biopolymers, such as polylactide, polysaccharides, aliphatic polyesters and polyhydroxyalkanoates is of interest. PHAs are biodegradable polyesters of hydroxyalkanoates (HA) produced from renewable resources by using microorganisms as intracellular carbon and energy storage compounds. Even though PHAs are promising candidate for biodegradable polymers, however, the production cost limit their application on an industrial scale. This article provides an overview of various substrates, microorganisms for the economical production of PHAs and its copolymers. Recent advances in PHAs to reduce the cost and to improve the performance of PHAs have also been discussed.
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Affiliation(s)
- Anbreen Anjum
- Institute of Chemistry, Government College University, Faisalabad 38030, Pakistan
| | - Mohammad Zuber
- Institute of Chemistry, Government College University, Faisalabad 38030, Pakistan.
| | - Khalid Mahmood Zia
- Institute of Chemistry, Government College University, Faisalabad 38030, Pakistan
| | - Aqdas Noreen
- Institute of Chemistry, Government College University, Faisalabad 38030, Pakistan
| | | | - Shazia Tabasum
- Institute of Chemistry, Government College University, Faisalabad 38030, Pakistan
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21
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Lin Z, Zhang Y, Yuan Q, Liu Q, Li Y, Wang Z, Ma H, Chen T, Zhao X. Metabolic engineering of Escherichia coli for poly(3-hydroxybutyrate) production via threonine bypass. Microb Cell Fact 2015; 14:185. [PMID: 26589676 PMCID: PMC4654888 DOI: 10.1186/s12934-015-0369-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 10/27/2015] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Poly(3-hydroxybutyrate) (PHB), have been considered to be good candidates for completely biodegradable polymers due to their similar mechanical properties to petroleum-derived polymers and complete biodegradability. Escherichia coli has been used to simulate the distribution of metabolic fluxes in recombinant E. coli producing poly(3-hydroxybutyrate) (PHB). Genome-scale metabolic network analysis can reveal unexpected metabolic engineering strategies to improve the production of biochemicals and biofuels. RESULTS In this study, we reported the discovery of a new pathway called threonine bypass by flux balance analysis of the genome-scale metabolic model of E. coli. This pathway, mainly containing the reactions for threonine synthesis and degradation, can potentially increase the yield of PHB and other acetyl-CoA derived products by reutilizing the CO2 released at the pyruvate dehydrogenase step. To implement the threonine bypass for PHB production in E. coli, we deregulated the threonine and serine degradation pathway and enhanced the threonine synthesis, resulting in 2.23-fold improvement of PHB titer. Then, we overexpressed glyA to enhance the conversion of glycine to serine and activated transhydrogenase to generate NADPH required in the threonine bypass. CONCLUSIONS The result strain TB17 (pBHR68) produced 6.82 g/L PHB with the yield of 0.36 g/g glucose in the shake flask fermentation and 35.92 g/L PHB with the yield of 0.23 g/g glucose in the fed-batch fermentation, which was almost 3.3-fold higher than the parent strain. The work outlined here shows that genome-scale metabolic network analysis can reveal novel metabolic engineering strategies for developing efficient microbial cell factories.
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Affiliation(s)
- Zhenquan Lin
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China.
| | - Yan Zhang
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China.
| | - Qianqian Yuan
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China. .,Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
| | - Qiaojie Liu
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China.
| | - Yifan Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China.
| | - Zhiwen Wang
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China.
| | - Hongwu Ma
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
| | - Tao Chen
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China. .,Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Nankai District, 92 Weijin Road, Tianjin, 300072, China.
| | - Xueming Zhao
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China. .,SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Edinburg-Tianjin Joint Research Centre for Systems Biology and Synthetic Biology, Tianjin University, Tianjin, 300072, China.
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22
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Metabolic Engineering of Escherichia coli for Poly(3-hydroxybutyrate) Production under Microaerobic Condition. BIOMED RESEARCH INTERNATIONAL 2015; 2015:789315. [PMID: 25945345 PMCID: PMC4405016 DOI: 10.1155/2015/789315] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 03/24/2015] [Accepted: 03/26/2015] [Indexed: 12/05/2022]
Abstract
The alcohol dehydrogenase promoter PadhE and mixed acid fermentation pathway deficient mutants of Escherichia coli were employed to produce poly(3-hydroxybutyrate) (P3HB) under microaerobic condition. The E. coli mutant with ackA-pta, poxB, ldhA, and adhE deletions accumulated 0.67 g/L P3HB, up to 78.84% of cell dry weight in tube cultivation. The deletion of pyruvate formate-lyase gene pflB drastically decreased P3HB production and P3HB content to 0.09 g/L and 24.44%, respectively. Overexpressing pflB via the plasmid in its knocked out mutant restored cell growth and P3HB accumulation, indicating the importance of the pyruvate formate-lyase in microaerobic carbon metabolism. The engineered E. coli BWapld (pWYC09) produced 5.00 g/L P3HB from 16.50 g/L glucose in 24 h batch fermentation, and P3HB production yield from glucose was 0.30 g/g, which reached up to 63% of maximal theoretical yield.
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23
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Krivoruchko A, Zhang Y, Siewers V, Chen Y, Nielsen J. Microbial acetyl-CoA metabolism and metabolic engineering. Metab Eng 2014; 28:28-42. [PMID: 25485951 DOI: 10.1016/j.ymben.2014.11.009] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 11/25/2014] [Accepted: 11/26/2014] [Indexed: 12/23/2022]
Abstract
Recent concerns over the sustainability of petrochemical-based processes for production of desired chemicals have fueled research into alternative modes of production. Metabolic engineering of microbial cell factories such as Saccharomyces cerevisiae and Escherichia coli offers a sustainable and flexible alternative for the production of various molecules. Acetyl-CoA is a key molecule in microbial central carbon metabolism and is involved in a variety of cellular processes. In addition, it functions as a precursor for many molecules of biotechnological relevance. Therefore, much interest exists in engineering the metabolism around the acetyl-CoA pools in cells in order to increase product titers. Here we provide an overview of the acetyl-CoA metabolism in eukaryotic and prokaryotic microbes (with a focus on S. cerevisiae and E. coli), with an emphasis on reactions involved in the production and consumption of acetyl-CoA. In addition, we review various strategies that have been used to increase acetyl-CoA production in these microbes.
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Affiliation(s)
- Anastasia Krivoruchko
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Yiming Zhang
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Verena Siewers
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Yun Chen
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Jens Nielsen
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
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24
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Wang Y, Yin J, Chen GQ. Polyhydroxyalkanoates, challenges and opportunities. Curr Opin Biotechnol 2014; 30:59-65. [DOI: 10.1016/j.copbio.2014.06.001] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 05/23/2014] [Accepted: 06/05/2014] [Indexed: 01/04/2023]
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25
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Kim EJ, Kim KJ. Crystal structure and biochemical characterization of PhaA from Ralstonia eutropha, a polyhydroxyalkanoate-producing bacterium. Biochem Biophys Res Commun 2014; 452:124-9. [DOI: 10.1016/j.bbrc.2014.08.074] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 08/14/2014] [Indexed: 11/24/2022]
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26
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Centeno-Leija S, Huerta-Beristain G, Giles-Gómez M, Bolivar F, Gosset G, Martinez A. Improving poly-3-hydroxybutyrate production in Escherichia coli by combining the increase in the NADPH pool and acetyl-CoA availability. Antonie van Leeuwenhoek 2014; 105:687-96. [PMID: 24500003 DOI: 10.1007/s10482-014-0124-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 01/22/2014] [Indexed: 10/25/2022]
Abstract
The biosynthesis of poly-3-hydroxybutyrate (P3HB), a biodegradable bio-plastic, requires acetyl-CoA as precursor and NADPH as cofactor. Escherichia coli has been used as a heterologous production model for P3HB, but metabolic pathway analysis shows a deficiency in maintaining high levels of NADPH and that the acetyl-CoA is mainly converted to acetic acid by native pathways. In this work the pool of NADPH was increased 1.7-fold in E. coli MG1655 through plasmid overexpression of the NADP(+)-dependent glyceraldehyde 3-phosphate dehydrogenase gene (gapN) from Streptococcus mutans (pTrcgapN). Additionally, by deleting the main acetate production pathway (ackA-pta), the acetic acid production was abolished, thus increasing the acetyl-CoA pool. The P3HB biosynthetic pathway was heterologously expressed in strain MG1655 Δack-pta/pTrcgapN, using an IPTG inducible vector with the P3HB operon from Azotobacter vinelandii (pPHB Av ). Cultures were performed in controlled fermentors using mineral medium with glucose as the carbon source. Accordingly, the mass yield of P3HB on glucose increased to 73 % of the maximum theoretical and was 30 % higher when compared to the progenitor strain (MG1655/pPHB Av ). In comparison with the wild type strain expressing pPHB Av , the specific accumulation of PHB (gPHB/gDCW) in MG1655 Δack-pta/pTrcgapN/pPHB Av increased twofold, indicating that as the availability of NADPH is raised and the production of acetate abolished, a P3HB intracellular accumulation of up to 84 % of the E. coli dry weight is attainable.
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Affiliation(s)
- Sara Centeno-Leija
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, 62250, Cuernavaca, Morelos, Mexico
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27
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Improvement on the yield of polyhydroxyalkanotes production from cheese whey by a recombinant Escherichia coli strain using the proton suicide methodology. Enzyme Microb Technol 2014; 55:151-8. [DOI: 10.1016/j.enzmictec.2013.11.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 10/16/2013] [Accepted: 11/12/2013] [Indexed: 10/26/2022]
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28
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Chen X, Zhou L, Tian K, Kumar A, Singh S, Prior BA, Wang Z. Metabolic engineering of Escherichia coli: A sustainable industrial platform for bio-based chemical production. Biotechnol Adv 2013; 31:1200-23. [DOI: 10.1016/j.biotechadv.2013.02.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/04/2013] [Accepted: 02/25/2013] [Indexed: 12/20/2022]
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29
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Kim J, Chang JH, Kim EJ, Kim KJ. Crystal structure of (R)-3-hydroxybutyryl-CoA dehydrogenase PhaB from Ralstonia eutropha. Biochem Biophys Res Commun 2013; 443:783-8. [PMID: 24211201 DOI: 10.1016/j.bbrc.2013.10.150] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 10/28/2013] [Indexed: 11/15/2022]
Abstract
(R)-3-hydroxybutyryl-CoA dehydrogenase PhaB from Ralstonia eutropha H16 (RePhaB) is an enzyme that catalyzes the NADPH-dependent reduction of acetoacetyl-CoA, an intermediate of polyhydroxyalkanoates (PHA) synthetic pathways. Polymeric PHA is used to make bioplastics, implant biomaterials, and biofuels. Here, we report the crystal structures of RePhaB apoenzyme and in complex with either NADP(+) or acetoacetyl-CoA, which provide the catalytic mechanism of the protein. RePhaB contains a Rossmann fold and a Clamp domain for binding of NADP(+) and acetoacetyl-CoA, respectively. The NADP(+)-bound form of RePhaB structure reveals that the protein has a unique cofactor binding mode. Interestingly, in the RePhaB structure in complex with acetoacetyl-CoA, the conformation of the Clamp domain, especially the Clamp-lid, undergoes a large structural change about 4.6 Å leading to formation of the substrate pocket. These structural observations, along with the biochemical experiments, suggest that movement of the Clamp-lid enables the substrate binding and ensures the acetoacetyl moiety is located near to the nicotinamide ring of NADP(+).
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Affiliation(s)
- Jieun Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology, Teachers College, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Eun-Jung Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea
| | - Kyung-Jin Kim
- Structural and Molecular Biology Laboratory, School of Life Sciences and Biotechnology, Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea.
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30
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Gao X, Jian J, Li WJ, Yang YC, Shen XW, Sun ZR, Wu Q, Chen GQ. Genomic study of polyhydroxyalkanoates producing Aeromonas hydrophila 4AK4. Appl Microbiol Biotechnol 2013; 97:9099-109. [PMID: 24000047 DOI: 10.1007/s00253-013-5189-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 08/07/2013] [Accepted: 08/11/2013] [Indexed: 11/30/2022]
Abstract
The complete genome of Gram-negative Aeromonas hydrophila 4AK4 that has been used for industrial production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) was sequenced and annotated. Its chromosome is 4,527,993 bp in size encoding 4,272 genes, including 28 rRNA genes and 104 tRNA genes. Comparative analysis indicated that genome of A. hydrophila 4AK4 was similar to that of the A. hydrophila ATCC 7966(T), an intensively studied aeromonad for its pathogenicity related to its genomic information. Genes possibly coming from other species or even other genus were identified in A. hydrophila 4AK4. A large number of putative virulent genes were predicted. However, a cytotonic enterotoxin (Ast) is absent in A. hydrophila 4AK4, allowing the industrial strain to be different from other A. hydrophila strains, indicating possible reduced virulence of strain 4AK4, which is very important for industrial fermentation. Genes involved in polyhydroxyalkanoate (PHA) metabolism were predicted and analyzed. The resulting genomic information is useful for improved production of PHA via metabolic engineering of A. hydrophila 4AK4.
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Affiliation(s)
- Xue Gao
- MOE Key Lab of Bioinformatics, School of Life Science, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
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Maximizing hydrogen production and substrate consumption by Escherichia coli WDHL in cheese whey fermentation. Appl Biochem Biotechnol 2013; 171:704-15. [PMID: 23881784 DOI: 10.1007/s12010-013-0394-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
Abstract
Fermentative hydrogen production is strongly affected by pH. In order to maximize hydrogen production and substrate consumption in Escherichia coli ΔhycA, ΔlacI (WDHL) cheese whey fermentation, the influence of pH control at values of 5.5, 6, and 6.5 was studied in batch stirred-tank bioreactors. From the conditions evaluated, pH 6.5 was the best condition, at which the highest cumulative hydrogen production and yield (1.78 mol H2/mol lactose) were obtained. Moreover, at this pH, all carbohydrates from the cheese whey were consumed, and a mix of ethanol and organic acids, mainly lactate, were produced from glucose, whereas galactose yielded acetate, ethanol, and succinate. Operating the reactor at pH 5.5 resulted in the highest maximum specific production rate, but smaller hydrogen yield because only glucose was metabolized and galactose was accumulated. At pH 6, not all cheese whey carbohydrates were consumed, and it was not favorable for hydrogen production. Lactose consumption and growth kinetics were not affected by the pH. The results show the importance of controlling pH to maximize hydrogen production and substrate consumption using cheese whey as substrate.
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The role of aldehyde/alcohol dehydrogenase (AdhE) in ethanol production from glycerol by Klebsiella pneumoniae. ACTA ACUST UNITED AC 2013; 40:227-33. [DOI: 10.1007/s10295-012-1224-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 12/09/2012] [Indexed: 11/26/2022]
Abstract
Abstract
Transcriptome analysis of a K. pneumoniae GEM167 mutant strain derived by irradiation with gamma rays, which exhibited high-level production of ethanol from glycerol, showed that the mutant expressed AdhE at a high level. Ethanol production decreased significantly, from 8.8 to 0.5 g l−1, when an adhE-deficient derivative of that strain was grown on glycerol. Bacterial growth was also reduced under such conditions, showing that AdhE plays a critical role in maintenance of redox balance by catalyzing ethanol production. Overexpression of AdhE enhanced ethanol production, from pure or crude glycerol, to a maximal level of 31.9 g l−1 under fed-batch fermentation conditions; this is the highest level of ethanol production from glycerol reported to date.
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Li S, Huang D, Li Y, Wen J, Jia X. Rational improvement of the engineered isobutanol-producing Bacillus subtilis by elementary mode analysis. Microb Cell Fact 2012; 11:101. [PMID: 22862776 PMCID: PMC3475101 DOI: 10.1186/1475-2859-11-101] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 07/13/2012] [Indexed: 01/08/2023] Open
Abstract
Background Isobutanol is considered as a leading candidate for the replacement of current fossil fuels, and expected to be produced biotechnologically. Owing to the valuable features, Bacillus subtilis has been engineered as an isobutanol producer, whereas it needs to be further optimized for more efficient production. Since elementary mode analysis (EMA) is a powerful tool for systematical analysis of metabolic network structures and cell metabolism, it might be of great importance in the rational strain improvement. Results Metabolic network of the isobutanol-producing B. subtilis BSUL03 was first constructed for EMA. Considering the actual cellular physiological state, 239 elementary modes (EMs) were screened from total 11,342 EMs for potential target prediction. On this basis, lactate dehydrogenase (LDH) and pyruvate dehydrogenase complex (PDHC) were predicted as the most promising inactivation candidates according to flux flexibility analysis and intracellular flux distribution simulation. Then, the in silico designed mutants were experimentally constructed. The maximal isobutanol yield of the LDH- and PDHC-deficient strain BSUL05 reached 61% of the theoretical value to 0.36 ± 0.02 C-mol isobutanol/C-mol glucose, which was 2.3-fold of BSUL03. Moreover, this mutant produced approximately 70 % more isobutanol to the maximal titer of 5.5 ± 0.3 g/L in fed-batch fermentations. Conclusions EMA was employed as a guiding tool to direct rational improvement of the engineered isobutanol-producing B. subtilis. The consistency between model prediction and experimental results demonstrates the rationality and accuracy of this EMA-based approach for target identification. This network-based rational strain improvement strategy could serve as a promising concept to engineer efficient B. subtilis hosts for isobutanol, as well as other valuable products.
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Affiliation(s)
- Shanshan Li
- Department of Biological Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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Liu F, Jian J, Shen X, Chung A, Chen J, Chen GQ. Metabolic engineering of Aeromonas hydrophila 4AK4 for production of copolymers of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoate. BIORESOURCE TECHNOLOGY 2011; 102:8123-8129. [PMID: 21680176 DOI: 10.1016/j.biortech.2011.05.074] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 05/24/2011] [Accepted: 05/25/2011] [Indexed: 05/30/2023]
Abstract
A mutant termed Aeromonas hydrophila AKLF was constructed by deleting acetic acid pathway related genes pta and ackA in A. hydrophila 4AK4. Accumulation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) in A. hydrophila AKLF was increased by 47% from 2.11 to 3.10g/L associated with a reduction on acetic acid formation compared with A. hydrophila 4AK4 when lauric acid was used as carbon resource. A. hydrophila AKLF harboring pVGAB encoding Vitreoscilla hemoglobin, β-ketothiolase and acetoacetyl-CoA reductase was found to produce 85% more PHBHHx compared to its wild type. Expression of plasmid pD(Ec)L(Pp) harboring genes related to fatty acid metabolism in A. hydrophila AKLF led to 63% more PHBHHx production than A. hydrophila 4AK4. Replacing phaC in A. hydrophila AKLF with a mutant phaC2 from Pseudomonas stutzeri 1317 resulted in enhanced production of copolymers of 3-hydroxybutyrate and medium-chain-length 3-hydroxyalkanoates compared to A. hydrophila 4AK4 harboring the mutant phaC2 in the chromosome as control.
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Affiliation(s)
- Feng Liu
- Protein Science Laboratory of the Ministry of Education, Department of Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
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Renilla S, Bernal V, Fuhrer T, Castaño-Cerezo S, Pastor JM, Iborra JL, Sauer U, Cánovas M. Acetate scavenging activity in Escherichia coli: interplay of acetyl-CoA synthetase and the PEP-glyoxylate cycle in chemostat cultures. Appl Microbiol Biotechnol 2011; 93:2109-24. [PMID: 21881893 DOI: 10.1007/s00253-011-3536-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 07/27/2011] [Accepted: 08/05/2011] [Indexed: 11/25/2022]
Abstract
Impairment of acetate production in Escherichia coli is crucial for the performance of many biotechnological processes. Aerobic production of acetate (or acetate overflow) results from changes in the expression of central metabolism genes. Acetyl-CoA synthetase scavenges extracellular acetate in glucose-limited cultures. Once converted to acetyl-CoA, it can be catabolized by the tricarboxylic acid cycle or the glyoxylate pathway. In this work, we assessed the significance of these pathways on acetate overflow during glucose excess and limitation. Gene expression, enzyme activities, and metabolic fluxes were studied in E. coli knock-out mutants related to the glyoxylate pathway operon and its regulators. The relevance of post-translational regulation by AceK-mediated phosphorylation of isocitrate dehydrogenase for pathway functionality was underlined. In chemostat cultures performed at increasing dilution rates, acetate overflow occurs when growing over a threshold glucose uptake rate. This threshold was not affected in a glyoxylate-pathway-deficient strain (lacking isocitrate lyase, the first enzyme of the pathway), indicating that it is not relevant for acetate overflow. In carbon-limited chemostat cultures, gluconeogenesis (maeB, sfcA, and pck), the glyoxylate operon and, especially, acetyl-CoA synthetase are upregulated. A mutant in acs (encoding acetyl-CoA synthetase) produced acetate at all dilution rates. This work demonstrates that, in E. coli, acetate production occurs at all dilution rates and that overflow is the result of unbalanced synthesis and scavenging activities. The over-expression of acetyl-CoA synthetase by cAMP-CRP-dependent induction limits this phenomenon in cultures consuming glucose at low rate, ensuring the recycling of the acetyl-CoA and acetyl-phosphate pools, although establishing an energy-dissipating substrate cycle.
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Affiliation(s)
- Sergio Renilla
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Chemistry, University of Murcia, Murcia, Spain
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Li S, Wen J, Jia X. Engineering Bacillus subtilis for isobutanol production by heterologous Ehrlich pathway construction and the biosynthetic 2-ketoisovalerate precursor pathway overexpression. Appl Microbiol Biotechnol 2011; 91:577-89. [PMID: 21533914 DOI: 10.1007/s00253-011-3280-9] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/24/2011] [Accepted: 03/26/2011] [Indexed: 12/14/2022]
Abstract
In the present work, Bacillus subtilis was engineered as the cell factory for isobutanol production due to its high tolerance to isobutanol. Initially, an efficient heterologous Ehrlich pathway controlled by the promoter P(43) was introduced into B. subtilis for the isobutanol biosynthesis. Further, investigation of acetolactate synthase of B. subtilis, ketol-acid reductoisomerase, and dihydroxy-acid dehydratase of Corynebacterium glutamicum responsible for 2-ketoisovalerate precursor biosynthesis showed that acetolactate synthase played an important role in isobutanol biosynthesis. The overexpression of acetolactate synthase led to a 2.8-fold isobutanol production compared with the control. Apart from isobutanol, alcoholic profile analysis also confirmed the existence of 1.21 g/L ethanol, 1.06 g/L 2-phenylethanol, as well as traces of 2-methyl-1-butanol and 3-methyl-1-butanol in the fermentation broth. Under microaerobic condition, the engineered B. subtilis produced up to 2.62 g/L isobutanol in shake-flask fed-batch fermentation, which was 21.3% higher than that in batch fermentation.
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Affiliation(s)
- Shanshan Li
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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Elimination of D-lactate synthesis increases poly(3-hydroxybutyrate) and ethanol synthesis from glycerol and affects cofactor distribution in recombinant Escherichia coli. Appl Environ Microbiol 2010; 76:7400-6. [PMID: 20870794 DOI: 10.1128/aem.02067-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effect of eliminating D-lactate synthesis in poly(3-hydroxybutyrate) (PHB)-accumulating recombinant Escherichia coli (K24K) was analyzed using glycerol as a substrate. K24KL, an ldhA derivative, produced more biomass and had altered carbon partitioning among the metabolic products, probably due to the increased availability of carbon precursors and reducing power. This resulted in a significant increase of PHB and ethanol synthesis and a decrease in acetate production. Cofactor measurements revealed that cultures of K24K and K24KL had a high intracellular NADPH content and that the NADPH/NADP(+) ratio was higher than the NADH/NAD(+) ratio. The ldhA mutation affected cofactor distribution, resulting in a more reduced intracellular state, mainly due to a further increase in NADPH/NADP(+). In 60-h fed-batch cultures, K24KL reached 41.9 g·liter⁻¹ biomass and accumulated PHB up to 63% ± 1% (wt/wt), with a PHB yield on glycerol of 0.41 ± 0.03 g·g⁻¹, the highest reported using this substrate.
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