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Chen J, Guo L, Zhang Y, Zhao M, Li M, Zhao Z, Qi Q, Xian M, Liu M, Zhao G. Metabolic Engineering of Escherichia coli for Bioproduction of ( R)-3-Hydroxybutyric Acid through a Three-Pronged Approach. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024. [PMID: 39024463 DOI: 10.1021/acs.jafc.4c04123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
(R)-3-Hydroxybutyric acid (R-3HB) is an important chiral chemical with extensive applications in the agricultural, food, and chemical industries. The synthesis of R-3HB by microbial fermentation is of interest due to its remarkable stereoselectivity and economy. However, the low production of R-3HB failed to meet the needs of large-scale industrial production. In this study, an engineered strain for the efficient biosynthesis of R-3HB was constructed through a three-pronged approach encompassing biosynthetic pathway optimization, engineering of NADPH regenerators, and central metabolism regulation. The engineered strain Q5081 produced 75.7 g/L R-3HB, with a productivity of 1.26 g/L/h and a yield of 0.34 g/g glucose in fed-batch fermentation, showing the highest reported titer and productivity of R-3HB to date. We also performed transcriptome sequencing and annotation to illustrate the mechanism underlying the enhanced R-3HB production. The systematic metabolic engineering by a three-pronged approach demonstrated the feasibility of improving the biosynthesis, and the engineered strain Q5081 has the potential for widespread applications in the industrial production of R-3HB.
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Affiliation(s)
- Jinhong Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Likun Guo
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Ying Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Mohan Zhao
- Qingdao No. 2 Middle School, Qingdao 266061, China
| | - Meijie Li
- Energy-Rich Compound Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Zhe Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Mo Xian
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Min Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Guang Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
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Rajpurohit H, Eiteman MA. Citrate synthase variants improve yield of acetyl-CoA derived 3-hydroxybutyrate in Escherichia coli. Microb Cell Fact 2024; 23:173. [PMID: 38867236 PMCID: PMC11167817 DOI: 10.1186/s12934-024-02444-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 05/29/2024] [Indexed: 06/14/2024] Open
Abstract
BACKGROUND The microbial chiral product (R)-3-hydroxybutyrate (3-HB) is a gateway to several industrial and medical compounds. Acetyl-CoA is the key precursor for 3-HB, and several native pathways compete with 3-HB production. The principal competing pathway in wild-type Escherichia coli for acetyl-CoA is mediated by citrate synthase (coded by gltA), which directs over 60% of the acetyl-CoA into the tricarboxylic acid cycle. Eliminating citrate synthase activity (deletion of gltA) prevents growth on glucose as the sole carbon source. In this study, an alternative approach is used to generate an increased yield of 3-HB: citrate synthase activity is reduced but not eliminated by targeted substitutions in the chromosomally expressed enzyme. RESULTS Five E. coli GltA variants were examined for 3-HB production via heterologous overexpression of a thiolase (phaA) and NADPH-dependent acetoacetyl-CoA reductase (phaB) from Cupriavidus necator. In shake flask studies, four variants showed nearly 5-fold greater 3-HB yield compared to the wild-type, although pyruvate accumulated. Overexpression of either native thioesterases TesB or YciA eliminated pyruvate formation, but diverted acetyl-CoA towards acetate formation. Overexpression of pantothenate kinase similarly decreased pyruvate formation but did not improve 3-HB yield. Controlled batch studies at the 1.25 L scale demonstrated that the GltA[A267T] variant produced the greatest 3-HB titer of 4.9 g/L with a yield of 0.17 g/g. In a phosphate-starved repeated batch process, E. coli ldhA poxB pta-ackA gltA::gltA[A267T] generated 15.9 g/L 3-HB (effective concentration of 21.3 g/L with dilution) with yield of 0.16 g/g from glucose as the sole carbon source. CONCLUSIONS This study demonstrates that GltA variants offer a means to affect the generation of acetyl-CoA derived products. This approach should benefit a wide range of acetyl-CoA derived biochemical products in E. coli and other microbes. Enhancing substrate affinity of the introduced pathway genes like thiolase towards acetyl-CoA will likely further increase the flux towards 3-HB while reducing pyruvate and acetate accumulation.
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Affiliation(s)
| | - Mark A Eiteman
- School of Chemical, Materials and Biomedical Engineering, Athens, GA, USA.
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA.
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Park JK, Jeon JM, Yang YH, Kim SH, Yoon JJ. Efficient polyhydroxybutyrate production using acetate by engineered Halomonas sp. JJY01 harboring acetyl-CoA acetyltransferase. Int J Biol Macromol 2024; 254:127475. [PMID: 37863147 DOI: 10.1016/j.ijbiomac.2023.127475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/05/2023] [Accepted: 10/15/2023] [Indexed: 10/22/2023]
Abstract
Polyhydroxybutyrate (PHB) is a well-known biodegradable bioplastic synthesized by microorganisms and can be produced from volatile fatty acids (VFAs). Among VFAs acetate can be utilized by Halomonas sp. YLGW01 for growth and PHB production. In this study, Halomonas sp. JJY01 was developed through introducing acetyl-CoA acetyltransferase (atoAD) with LacIq-Ptrc promoter into Halomonas sp. YLGW01. The effect of expression of atoAD on acetate was investigated by comparison with acetate consumption and PHB production. Shake-flask study showed that Halomonas sp. JJY01 increased acetate consumption rate, PHB yield and PHB production (0.27 g/L/h, 0.075 g/g, 0.72 g/L) compared to the wild type strain (0.17 g/L/h, 0.016 g/g, 0.11 g/L). In 10 L fermenter scale fed-batch fermentation, the growth of Halomonas sp. JJY01 resulted in higher acetate consumption rate, PHB yield and PHB titer (0.55 g/L/h, 0.091 g/g, 4.6 g/L) than wild type strain (0.35 g/L/h, 0.067 h/h, 2.9 g/L). These findings demonstrate enhanced acetate utilization and PHB production through the introduction of atoAD in Halomonas strains.
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Affiliation(s)
- Jea-Kyung Park
- Green & Sustainable Materials R&D Department, Korea Institute of Industrial Technology (KITECH), Cheonan-si 31056, Republic of Korea; School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Jong-Min Jeon
- Green & Sustainable Materials R&D Department, Korea Institute of Industrial Technology (KITECH), Cheonan-si 31056, Republic of Korea
| | - Yung-Hun Yang
- Department of Biological Engineering, Konkuk University, Seoul 05029, Republic of Korea
| | - Sang-Hyoun Kim
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Jeong-Jun Yoon
- Green & Sustainable Materials R&D Department, Korea Institute of Industrial Technology (KITECH), Cheonan-si 31056, Republic of Korea.
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Lo J, Humphreys JR, Magnusson L, Wachter B, Urban C, Hebdon SD, Xiong W, Chou KJ, Ching Maness P. Acetogenic production of 3-Hydroxybutyrate using a native 3-Hydroxybutyryl-CoA Dehydrogenase. Front Microbiol 2022; 13:948369. [PMID: 36003933 PMCID: PMC9393629 DOI: 10.3389/fmicb.2022.948369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022] Open
Abstract
3-Hydroxybutyrate (3HB) is a product of interest as it is a precursor to the commercially produced bioplastic polyhydroxybutyrate. It can also serve as a platform for fine chemicals, medicines, and biofuels, making it a value-added product and feedstock. Acetogens non-photosynthetically fix CO2 into acetyl-CoA and have been previously engineered to convert acetyl-CoA into 3HB. However, as acetogen metabolism is poorly understood, those engineering efforts have had varying levels of success. 3HB, using acetyl-CoA as a precursor, can be synthesized by a variety of different pathways. Here we systematically compare various pathways to produce 3HB in acetogens and discover a native (S)-3-hydroxybutyryl-CoA dehydrogenase, hbd2, responsible for endogenous 3HB production. In conjunction with the heterologous thiolase atoB and CoA transferase ctfAB, hbd2 overexpression improves yields of 3HB on both sugar and syngas (CO/H2/CO2), outperforming the other tested pathways. These results uncovered a previously unknown 3HB production pathway, inform data from prior metabolic engineering efforts, and have implications for future physiological and biotechnological anaerobic research.
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Miscevic D, Srirangan K, Kefale T, Kilpatrick S, Chung DA, Moo-Young M, Chou CP. Heterologous production of 3-hydroxyvalerate in engineered Escherichia coli. Metab Eng 2020; 61:141-151. [DOI: 10.1016/j.ymben.2019.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/25/2019] [Accepted: 11/09/2019] [Indexed: 10/25/2022]
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Engineered citrate synthase alters Acetate Accumulation in Escherichia coli. Metab Eng 2020; 61:171-180. [PMID: 32569710 DOI: 10.1016/j.ymben.2020.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/24/2020] [Accepted: 06/10/2020] [Indexed: 12/15/2022]
Abstract
Metabolic engineering is used to improve titers, yields and generation rates for biochemical products in host microbes such as Escherichia coli. A wide range of biochemicals are derived from the central carbon metabolite acetyl-CoA, and the largest native drain of acetyl-CoA in most microbes including E. coli is entry into the tricarboxylic acid (TCA) cycle via citrate synthase (coded by the gltA gene). Since the pathway to any biochemical derived from acetyl-CoA must ultimately compete with citrate synthase, a reduction in citrate synthase activity should facilitate the increased formation of products derived from acetyl-CoA. To test this hypothesis, we integrated into E. coli C ΔpoxB twenty-eight citrate synthase variants having specific point mutations that were anticipated to reduce citrate synthase activity. These variants were assessed in shake flasks for growth and the production of acetate, a model product derived from acetyl-CoA. Mutations in citrate synthase at residues W260, A267 and V361 resulted in the greatest acetate yields (approximately 0.24 g/g glucose) compared to the native citrate synthase (0.05 g/g). These variants were further examined in controlled batch and continuous processes. The results provide important insights on improving the production of compounds derived from acetyl-CoA.
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Kelwick RJR, Webb AJ, Freemont PS. Biological Materials: The Next Frontier for Cell-Free Synthetic Biology. Front Bioeng Biotechnol 2020; 8:399. [PMID: 32478045 PMCID: PMC7235315 DOI: 10.3389/fbioe.2020.00399] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 04/08/2020] [Indexed: 12/13/2022] Open
Abstract
Advancements in cell-free synthetic biology are enabling innovations in sustainable biomanufacturing, that may ultimately shift the global manufacturing paradigm toward localized and ecologically harmonized production processes. Cell-free synthetic biology strategies have been developed for the bioproduction of fine chemicals, biofuels and biological materials. Cell-free workflows typically utilize combinations of purified enzymes, cell extracts for biotransformation or cell-free protein synthesis reactions, to assemble and characterize biosynthetic pathways. Importantly, cell-free reactions can combine the advantages of chemical engineering with metabolic engineering, through the direct addition of co-factors, substrates and chemicals -including those that are cytotoxic. Cell-free synthetic biology is also amenable to automatable design cycles through which an array of biological materials and their underpinning biosynthetic pathways can be tested and optimized in parallel. Whilst challenges still remain, recent convergences between the materials sciences and these advancements in cell-free synthetic biology enable new frontiers for materials research.
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Affiliation(s)
- Richard J. R. Kelwick
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Alexander J. Webb
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Paul S. Freemont
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, United Kingdom
- The London Biofoundry, Imperial College Translation & Innovation Hub, London, United Kingdom
- UK Dementia Research Institute Care Research and Technology Centre, Imperial College London, London, United Kingdom
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Yañez L, Conejeros R, Vergara-Fernández A, Scott F. Beyond Intracellular Accumulation of Polyhydroxyalkanoates: Chiral Hydroxyalkanoic Acids and Polymer Secretion. Front Bioeng Biotechnol 2020; 8:248. [PMID: 32318553 PMCID: PMC7147478 DOI: 10.3389/fbioe.2020.00248] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/10/2020] [Indexed: 01/05/2023] Open
Abstract
Polyhydroxyalkanoates (PHAs) are ubiquitous prokaryotic storage compounds of carbon and energy, acting as sinks for reducing power during periods of surplus of carbon source relative to other nutrients. With close to 150 different hydroxyalkanoate monomers identified, the structure and properties of these polyesters can be adjusted to serve applications ranging from food packaging to biomedical uses. Despite its versatility and the intensive research in the area over the last three decades, the market share of PHAs is still low. While considerable rich literature has accumulated concerning biochemical, physiological, and genetic aspects of PHAs intracellular accumulation, the costs of substrates and processing costs, including the extraction of the polymer accumulated in intracellular granules, still hampers a more widespread use of this family of polymers. This review presents a comprehensive survey and critical analysis of the process engineering and metabolic engineering strategies reported in literature aimed at the production of chiral (R)-hydroxycarboxylic acids (RHAs), either from the accumulated polymer or by bypassing the accumulation of PHAs using metabolically engineered bacteria, and the strategies developed to recover the accumulated polymer without using conventional downstream separations processes. Each of these topics, that have received less attention compared to PHAs accumulation, could potentially improve the economy of PHAs production and use. (R)-hydroxycarboxylic acids can be used as chiral precursors, thanks to its easily modifiable functional groups, and can be either produced de-novo or be obtained from recycled PHA products. On the other hand, efficient mechanisms of PHAs release from bacterial cells, including controlled cell lysis and PHA excretion, could reduce downstream costs and simplify the polymer recovery process.
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Affiliation(s)
- Luz Yañez
- Green Technology Research Group, Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Santiago, Chile
| | - Raúl Conejeros
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Alberto Vergara-Fernández
- Green Technology Research Group, Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Santiago, Chile
| | - Felipe Scott
- Green Technology Research Group, Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Santiago, Chile
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Guevara-Martínez M, Perez-Zabaleta M, Gustavsson M, Quillaguamán J, Larsson G, van Maris AJA. The role of the acyl-CoA thioesterase "YciA" in the production of (R)-3-hydroxybutyrate by recombinant Escherichia coli. Appl Microbiol Biotechnol 2019; 103:3693-3704. [PMID: 30834961 PMCID: PMC6469607 DOI: 10.1007/s00253-019-09707-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 02/04/2019] [Accepted: 02/18/2019] [Indexed: 12/17/2022]
Abstract
Biotechnologically produced (R)-3-hydroxybutyrate is an interesting pre-cursor for antibiotics, vitamins, and other molecules benefitting from enantioselective production. An often-employed pathway for (R)-3-hydroxybutyrate production in recombinant E. coli consists of three-steps: (1) condensation of two acetyl-CoA molecules to acetoacetyl-CoA, (2) reduction of acetoacetyl-CoA to (R)-3-hydroxybutyrate-CoA, and (3) hydrolysis of (R)-3-hydroxybutyrate-CoA to (R)-3-hydroxybutyrate by thioesterase. Whereas for the first two steps, many proven heterologous candidate genes exist, the role of either endogenous or heterologous thioesterases is less defined. This study investigates the contribution of four native thioesterases (TesA, TesB, YciA, and FadM) to (R)-3-hydroxybutyrate production by engineered E. coli AF1000 containing a thiolase and reductase from Halomonas boliviensis. Deletion of yciA decreased the (R)-3-hydroxybutyrate yield by 43%, whereas deletion of tesB and fadM resulted in only minor decreases. Overexpression of yciA resulted in doubling of (R)-3-hydroxybutyrate titer, productivity, and yield in batch cultures. Together with overexpression of glucose-6-phosphate dehydrogenase, this resulted in a 2.7-fold increase in the final (R)-3-hydroxybutyrate concentration in batch cultivations and in a final (R)-3-hydroxybutyrate titer of 14.3 g L−1 in fed-batch cultures. The positive impact of yciA overexpression in this study, which is opposite to previous results where thioesterase was preceded by enzymes originating from different hosts or where (S)-3-hydroxybutyryl-CoA was the substrate, shows the importance of evaluating thioesterases within a specific pathway and in strains and cultivation conditions able to achieve significant product titers. While directly relevant for (R)-3-hydroxybutyrate production, these findings also contribute to pathway improvement or decreased by-product formation for other acyl-CoA-derived products.
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Affiliation(s)
- Mónica Guevara-Martínez
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, SE 10691, Stockholm, Sweden.,Faculty of Science and Technology, Center of Biotechnology, Universidad Mayor de San Simón, Cochabamba, Bolivia
| | - Mariel Perez-Zabaleta
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, SE 10691, Stockholm, Sweden.,Faculty of Science and Technology, Center of Biotechnology, Universidad Mayor de San Simón, Cochabamba, Bolivia
| | - Martin Gustavsson
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, SE 10691, Stockholm, Sweden
| | - Jorge Quillaguamán
- Faculty of Science and Technology, Center of Biotechnology, Universidad Mayor de San Simón, Cochabamba, Bolivia
| | - Gen Larsson
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, SE 10691, Stockholm, Sweden
| | - Antonius J A van Maris
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, SE 10691, Stockholm, Sweden.
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Takenoya M, Taguchi S, Yajima S. Crystal structure and kinetic analyses of a hexameric form of (S)-3-hydroxybutyryl-CoA dehydrogenase from Clostridium acetobutylicum. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2018; 74:733-740. [PMID: 30387779 DOI: 10.1107/s2053230x18014814] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/19/2018] [Indexed: 11/11/2022]
Abstract
(S)-3-Hydroxybutyryl-CoA dehydrogenase (HBD) has been gaining increased attention recently as it is a key enzyme in the enantiomeric formation of (S)-3-hydroxybutyryl-CoA [(S)-3HB-CoA]. It converts acetoacetyl-CoA to (S)-3HB-CoA in the synthetic metabolic pathway. (S)-3HB-CoA is further modified to form (S)-3-hydroxybutyrate, which is a source of biodegradable polymers. During the course of a study to develop biodegradable polymers, attempts were made to determine the crystal structure of HBD from Clostridium acetobutylicum (CacHBD), and the crystal structures of both apo and NAD+-bound forms of CacHBD were determined. The crystals belonged to different space groups: P212121 and P21. However, both structures adopted a hexamer composed of three dimers in the asymmetric unit, and this oligomerization was additionally confirmed by gel-filtration column chromatography. Furthermore, to investigate the catalytic residues of CacHBD, the enzymatic activities of the wild type and of three single-amino-acid mutants were analyzed, in which the Ser, His and Asn residues that are conserved in the HBDs from C. acetobutylicum, C. butyricum and Ralstonia eutropha, as well as in the L-3-hydroxyacyl-CoA dehydrogenases from Homo sapiens and Escherichia coli, were substituted by alanines. The S117A and N188A mutants abolished the activity, while the H138A mutant showed a slightly lower Km value and a significantly lower kcat value than the wild type. Therefore, in combination with the crystal structures, it was shown that His138 is involved in catalysis and that Ser117 and Asn188 may be important for substrate recognition to place the keto group of the substrate in the correct position for reaction.
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Affiliation(s)
- Mihoko Takenoya
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan
| | - Seiichi Taguchi
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Shunsuke Yajima
- Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan
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Kelwick R, Ricci L, Chee SM, Bell D, Webb AJ, Freemont PS. Cell-free prototyping strategies for enhancing the sustainable production of polyhydroxyalkanoates bioplastics. Synth Biol (Oxf) 2018; 3:ysy016. [PMID: 32995523 PMCID: PMC7445755 DOI: 10.1093/synbio/ysy016] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 07/29/2018] [Accepted: 08/21/2018] [Indexed: 12/31/2022] Open
Abstract
The polyhydroxyalkanoates (PHAs) are microbially-produced biopolymers that could potentially be used as sustainable alternatives to oil-derived plastics. However, PHAs are currently more expensive to produce than oil-derived plastics. Therefore, more efficient production processes would be desirable. Cell-free metabolic engineering strategies have already been used to optimize several biosynthetic pathways and we envisioned that cell-free strategies could be used for optimizing PHAs biosynthetic pathways. To this end, we developed several Escherichia coli cell-free systems for in vitro prototyping PHAs biosynthetic operons, and also for screening relevant metabolite recycling enzymes. Furthermore, we customized our cell-free reactions through the addition of whey permeate, an industrial waste that has been previously used to optimize in vivo PHAs production. We found that the inclusion of an optimal concentration of whey permeate enhanced relative cell-free GFPmut3b production by approximately 50%. In cell-free transcription-translation prototyping reactions, gas chromatography-mass spectrometry quantification of cell-free 3-hydroxybutyrate (3HB) production revealed differences between the activities of the Native ΔPhaC_C319A (1.18 ± 0.39 µM), C104 ΔPhaC_C319A (4.62 ± 1.31 µM) and C101 ΔPhaC_C319A (2.65 ± 1.27 µM) phaCAB operons that were tested. Interestingly, the most active operon, C104 produced higher levels of PHAs (or PHAs monomers) than the Native phaCAB operon in both in vitro and in vivo assays. Coupled cell-free biotransformation/transcription-translation reactions produced greater yields of 3HB (32.87 ± 6.58 µM), and these reactions were also used to characterize a Clostridium propionicum Acetyl-CoA recycling enzyme. Together, these data demonstrate that cell-free approaches complement in vivo workflows for identifying additional strategies for optimizing PHAs production.
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Affiliation(s)
- Richard Kelwick
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London, UK
| | - Luca Ricci
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London, UK
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Soo Mei Chee
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
- The London DNA Foundry, Imperial College London, London, UK
| | - David Bell
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
- The London DNA Foundry, Imperial College London, London, UK
| | - Alexander J Webb
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London, UK
| | - Paul S Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
- Centre for Synthetic Biology and Innovation, Imperial College London, London, UK
- The London DNA Foundry, Imperial College London, London, UK
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Kadoya R, Matsumoto K, Takisawa K, Ooi T, Taguchi S. Enhanced production of lactate-based polyesters in Escherichia coli from a mixture of glucose and xylose by Mlc-mediated catabolite derepression. J Biosci Bioeng 2018; 125:365-370. [DOI: 10.1016/j.jbiosc.2017.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 10/18/2022]
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13
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Biernacki M, Riechen J, Hähnel U, Roick T, Baronian K, Bode R, Kunze G. Production of (R)-3-hydroxybutyric acid by Arxula adeninivorans. AMB Express 2017; 7:4. [PMID: 28050847 PMCID: PMC5209319 DOI: 10.1186/s13568-016-0303-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 12/11/2016] [Indexed: 12/28/2022] Open
Abstract
(R)-3-hydroxybutyric acid can be used in industrial and health applications. The synthesis pathway comprises two enzymes, β-ketothiolase and acetoacetyl-CoA reductase which convert cytoplasmic acetyl-CoA to (R)-3-hydroxybutyric acid [(R)-3-HB] which is released into the culture medium. In the present study we used the non-conventional yeast, Arxula adeninivorans, for the synthesis enantiopure (R)-3-HB. To establish optimal production, we investigated three different endogenous yeast thiolases (Akat1p, Akat2p, Akat4p) and three bacterial thiolases (atoBp, thlp, phaAp) in combination with an enantiospecific reductase (phaBp) from Cupriavidus necator H16 and endogenous yeast reductases (Atpk2p, Afox2p). We found that Arxula is able to release (R)-3-HB used an existing secretion system negating the need to engineer membrane transport. Overexpression of thl and phaB genes in organisms cultured in a shaking flask resulted in 4.84 g L−1 (R)-3-HB, at a rate of 0.023 g L−1 h−1 over 214 h. Fed-batch culturing with glucose as a carbon source did not improve the yield, but a similar level was reached with a shorter incubation period [3.78 g L−1 of (R)-3-HB at 89 h] and the rate of production was doubled to 0.043 g L−1 h−1 which is higher than any levels in yeast reported to date. The secreted (R)-3-HB was 99.9% pure. This is the first evidence of enantiopure (R)-3-HB synthesis using yeast as a production host and glucose as a carbon source.
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Wu L, Guo X, Lyu Y, Clarke SL, Lucas EA, Smith BJ, Hildebrand D, Wang W, Medeiros DM, Shen X, Lin D. Targeted Metabolomics Reveals Abnormal Hepatic Energy Metabolism by Depletion of β-Carotene Oxygenase 2 in Mice. Sci Rep 2017; 7:14624. [PMID: 29116185 PMCID: PMC5677115 DOI: 10.1038/s41598-017-15222-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/23/2017] [Indexed: 12/20/2022] Open
Abstract
β-carotene oxygenase 2 (BCO2) is a carotenoid cleavage enzyme located in the inner mitochondrial membrane. Ablation of BCO2 impairs mitochondrial function leading to oxidative stress. Herein, we performed a targeted metabolomics study using ultrahigh performance liquid chromatography-tandem mass spectroscopy and gas chromatography-mass spectroscopy to discriminate global metabolites profiles in liver samples from six-week-old male BCO2 systemic knockout (KO), heterozygous (Het), and wild type (WT) mice fed a chow diet. Principal components analysis revealed distinct differences in metabolites in the livers of KO mice, compared to WT and Het mice. However, no marked difference was found in the metabolites of the Het mouse liver compared to the WT. We then conducted random forest analysis to classify the potential biomarkers to further elucidate the different metabolomics profiles. We found that systemic ablation of BCO2 led to perturbations in mitochondrial function and metabolism in the TCA cycle, amino acids, carnitine, lipids, and bile acids. In conclusion, BCO2 is essential to macronutrient and mitochondrial metabolism in the livers of mice. The ablation of BCO2 causes dysfunctional mitochondria and altered energy metabolism, which further leads to systemic oxidative stress and inflammation. A single functional copy of BCO2 largely rescues the hepatic metabolic homeostasis in mice.
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Affiliation(s)
- Lei Wu
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Xin Guo
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Yi Lyu
- College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, 210046, China
| | - Stephen L Clarke
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Edralin A Lucas
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Brenda J Smith
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Deana Hildebrand
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA
| | - Weiqun Wang
- Department of Food, Nutrition, Dietetics, and Health, Kansas State University, Manhattan, KS, 66506, USA
| | - Denis M Medeiros
- Graduate School, University of Missouri, Kansas City, MO, 64110, USA
| | - Xinchun Shen
- College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, 210046, China
| | - Dingbo Lin
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma, 74078, USA.
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Mordhorst S, Maurer A, Popadić D, Brech J, Andexer JN. A Flexible Polyphosphate-Driven Regeneration System for Coenzyme A Dependent Catalysis. ChemCatChem 2017. [DOI: 10.1002/cctc.201700848] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Silja Mordhorst
- Institute of Pharmaceutical Sciences; University of Freiburg; Albertstrasse 25 79104 Freiburg Germany
| | - Alice Maurer
- Institute of Pharmaceutical Sciences; University of Freiburg; Albertstrasse 25 79104 Freiburg Germany
| | - Désirée Popadić
- Institute of Pharmaceutical Sciences; University of Freiburg; Albertstrasse 25 79104 Freiburg Germany
| | - Johanna Brech
- Institute of Pharmaceutical Sciences; University of Freiburg; Albertstrasse 25 79104 Freiburg Germany
| | - Jennifer N. Andexer
- Institute of Pharmaceutical Sciences; University of Freiburg; Albertstrasse 25 79104 Freiburg Germany
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Kadoya R, Kodama Y, Matsumoto K, Ooi T, Taguchi S. Genome-wide screening of transcription factor deletion targets in Escherichia coli for enhanced production of lactate-based polyesters. J Biosci Bioeng 2017; 123:535-539. [DOI: 10.1016/j.jbiosc.2016.12.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 12/12/2016] [Accepted: 12/15/2016] [Indexed: 01/19/2023]
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17
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Takisawa K, Ooi T, Matsumoto K, Kadoya R, Taguchi S. Xylose-based hydrolysate from eucalyptus extract as feedstock for poly(lactate-co-3-hydroxybutyrate) production in engineered Escherichia coli. Process Biochem 2017. [DOI: 10.1016/j.procbio.2016.12.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Kawata Y, Nojiri M, Matsushita I, Tsubota J. Improvement of (R)-3-hydroxybutyric acid secretion during Halomonas sp. KM-1 cultivation with saccharified Japanese cedar by the addition of urea. Lett Appl Microbiol 2015; 61:397-402. [PMID: 26249654 DOI: 10.1111/lam.12473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 07/18/2015] [Accepted: 07/28/2015] [Indexed: 11/27/2022]
Abstract
UNLABELLED Japanese cedar (Cryptomeria japonica) is a major species in artificial Japanese forests. The Halomonas sp. KM-1 was recently isolated and found to grow effectively on saccharified Japanese cedar wood, resulting in the intracellular storage of poly-(R)-3-hydroxybutyric acid (PHB) under aerobic conditions. Under microaerobic conditions, the extracellular secretion of (R)-3-hydroxybutyric acid ((R)-3-HB) led to the degradation of intracellular PHB. In this study, the production of PHB and the secretion of (R)-3-HB using saccharified Japanese cedar were much improved in cultures that were grown in the presence of urea. The level of intracellular PHB production after 36 h under aerobic cultivation was 23·6 g l(-1) ; after shifting to microaerobic conditions for 24 h, the (R)-3-HB concentration in the medium reached 21·1 g l(-1) . Thus, KM-1 efficiently utilizes saccharified Japanese cedar to produce PHB and secretes (R)-3-HB, making it a practical candidate for use in the industrial production of (R)-3-HB. SIGNIFICANCE AND IMPACT OF THE STUDY Japanese cedar is a major species grown in artificial Japanese forests, and its thinning is crucial for the health of artificial forests and the Japanese economy. Halomonas sp. KM-1 grew effectively on saccharified Japanese cedar wood, resulting in intracellular storage of poly-(R)-3-hydroxybutyric acid (PHB) under aerobic conditions. Under microaerobic conditions, extracellular secretion of (R)-3-hydroxybutyric acid ((R)-3-HB) caused intracellular PHB degradation. (R)-3-HB is a chiral compound that is useful in the chemical, health food and pharmaceutical industries. The production of PHB and secretion of (R)-3-HB using saccharified wood was dramatically improved, which may positively affect its future industrial production.
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Affiliation(s)
- Y Kawata
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka, Japan
| | - M Nojiri
- Forestry and Forest Products Research Institute (FFPRI), Tsukuba, Japan
| | - I Matsushita
- Energy Technology Laboratories, Osaka Gas Co., Ltd., Konohana-ku, Osaka, Japan
| | - J Tsubota
- Energy Technology Laboratories, Osaka Gas Co., Ltd., Konohana-ku, Osaka, Japan
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Kadoya R, Matsumoto K, Ooi T, Taguchi S. MtgA Deletion-Triggered Cell Enlargement of Escherichia coli for Enhanced Intracellular Polyester Accumulation. PLoS One 2015; 10:e0125163. [PMID: 26039058 PMCID: PMC4454544 DOI: 10.1371/journal.pone.0125163] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 03/12/2015] [Indexed: 11/18/2022] Open
Abstract
Bacterial polyester polyhydroxyalkanoates (PHAs) have been produced in engineered Escherichia coli, which turned into an efficient and versatile platform by applying metabolic and enzyme engineering approaches. The present study aimed at drawing out the latent potential of this organism using genome-wide mutagenesis. To meet this goal, a transposon-based mutagenesis was carried out on E. coli, which was transformed to produce poly(lactate-co-3-hydroxybutyrate) from glucose. A high-throughput screening of polymer-accumulating cells on Nile red-containing plates isolated one mutant that produced 1.8-fold higher quantity of polymer without severe disadvantages in the cell growth and monomer composition of the polymer. The transposon was inserted into the locus within the gene encoding MtgA that takes part, as a non-lethal component, in the formation of the peptidoglycan backbone. Accordingly, the mtgA-deleted strain E. coli JW3175, which was a derivate of superior PHA-producing strain BW25113, was examined for polymer production, and exhibited an enhanced accumulation of the polymer (7.0 g/l) compared to the control (5.2 g/l). Interestingly, an enlargement in cell width associated with polymer accumulation was observed in this strain, resulting in a 1.6-fold greater polymer accumulation per cell compared to the control. This result suggests that the increase in volumetric capacity for accumulating intracellular material contributed to the enhanced polymer production. The mtgA deletion should be combined with conventional engineering approaches, and thus, is a promising strategy for improved production of intracellularly accumulated biopolymers.
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Affiliation(s)
- Ryosuke Kadoya
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Ken'ichiro Matsumoto
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Toshihiko Ooi
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Seiichi Taguchi
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
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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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21
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Wang Y, Liu S. Production of (R)-3-hydroxybutyric acid by Burkholderia cepacia from wood extract hydrolysates. AMB Express 2014; 4:28. [PMID: 24949263 PMCID: PMC4052727 DOI: 10.1186/s13568-014-0028-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 01/06/2014] [Indexed: 11/10/2022] Open
Abstract
(R)-hydroxyalkanoic acids (R-HAs) are valuable building blocks for the synthesis of fine chemicals and biopolymers because of the chiral center and the two active functional groups. Hydroxyalkanoic acids fermentation can revolutionize the polyhydroxyalkanoic acids (PHA) production by increasing efficiency and enhancing product utility. Modifying the fermentation conditions that promotes the in vivo depolymerization and secretion to fermentation broth in wild type bacteria is a novel and promising approach to produce R-HAs. Wood extract hydrolysate (WEH) was found to be a suitable substrate for R-3-hydroxybutyric acid (R-3-HB) production by Burkholderia cepacia. Using Paulownia elongate WEH as a feedstock, the R-3-HB concentration in fermentation broth reached as high as 14.2 g/L after 3 days of batch fermentation and the highest concentration of 16.8 g/L was obtained at day 9. Further investigation indicated that the composition of culture medium contributed to the enhanced R-3-HB production.
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22
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Kawata Y, Ando H, Matsushita I, Tsubota J. Efficient secretion of (R)-3-hydroxybutyric acid from Halomonas sp. KM-1 by nitrate fed-batch cultivation with glucose under microaerobic conditions. BIORESOURCE TECHNOLOGY 2014; 156:400-403. [PMID: 24503050 DOI: 10.1016/j.biortech.2014.01.073] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/19/2014] [Indexed: 06/03/2023]
Abstract
To establish a sustainable society, commodity chemicals need to be developed from biomass resources. Recently, (R)-3-hydroxybutyric acid ((R)-3-HB), a monomer of bioplastic poly-(R)-3-hydroxybutyric acid (PHB), has attracted attention for its possible use in the chemical industry. Halophilic bacteria have been considered for bioprocess applications due to certain characteristics such as the ability to grow in media containing high levels of the starting carbon source and the ability to be rarely contaminated. A halophilic bacterium Halomonas sp. KM-1 stores PHB intracellularly under aerobic conditions and secretes (R)-3-HB under microaerobic conditions. In this study, we optimized culture conditions to maximize (R)-3-HB secretion by KM-1 cells. By a simple nitrate fed-batch cultivation, Halomonas sp. KM-1 secreted 40.3g/L (R)-3-HB with a productivity of 0.48g L(-1)h(-1) with 20% (w/v) glucose. This level is one of the highest recorded productivity of (R)-3-HB to date.
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Affiliation(s)
- Yoshikazu Kawata
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.
| | - Hitoshi Ando
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Isao Matsushita
- Energy Technology Laboratories, OSAKA GAS CO., LTD., 6-19-9 Torishima, Konohana-ku, Osaka 554-0051, Japan
| | - Jun Tsubota
- Energy Technology Laboratories, OSAKA GAS CO., LTD., 6-19-9 Torishima, Konohana-ku, Osaka 554-0051, Japan
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Nduko JM, Matsumoto K, Ooi T, Taguchi S. Enhanced production of poly(lactate-co-3-hydroxybutyrate) from xylose in engineered Escherichia coli overexpressing a galactitol transporter. Appl Microbiol Biotechnol 2013; 98:2453-60. [PMID: 24337250 DOI: 10.1007/s00253-013-5401-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/11/2013] [Accepted: 11/11/2013] [Indexed: 10/25/2022]
Abstract
Poly(lactate-co-3-hydroxybutyrate) (P(LA-co-3HB)) was previously produced from xylose in engineered Escherichia coli. The aim of this study was to increase the polymer productivity and LA fraction in P(LA-co-3HB) using two metabolic engineering approaches: (1) deletions of competing pathways to lactate production and (2) overexpression of a galactitol transporter (GatC), which contributes to the ATP-independent xylose uptake. Engineered E. coli mutants (ΔpflA, Δpta, ΔackA, ΔpoxB, Δdld, and a dual mutant; ΔpflA + Δdld) and their parent strain, BW25113, were grown on 20 g l(-1) xylose for P(LA-co-3HB) production. The single deletions of ΔpflA, Δpta, and Δdld increased the LA fraction (58-66 mol%) compared to BW25113 (56 mol%). In particular, the ΔpflA + Δdld strain produced P(LA-co-3HB) containing 73 mol% LA. Furthermore, GatC overexpression increased both polymer yields and LA fractions in ΔpflA, Δpta, and Δdld mutants, and BW25113. The ΔpflA + gatC strain achieved a productivity of 8.3 g l(-1), which was 72 % of the theoretical maximum yield. Thus, to eliminate limitation of the carbon source, higher concentration of xylose was fed. As a result, BW25113 harboring gatC grown on 40 g l(-1) xylose reached the highest P(LA-co-3HB) productivity of 14.4 g l(-1). On the other hand, the ΔpflA + Δdld strain grown on 30 g l(-1) xylose synthesized 6.4 g l(-1) P(LA-co-3HB) while maintaining the highest LA fraction (73 mol%). The results indicated the usefulness of GatC for enhanced production of P(LA-co-3HB) from xylose, and the gene deletions to upregulate the LA fraction in P(LA-co-3HB). The polymers obtained had weight-averaged molecular weights in the range of 34,000-114,000.
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Affiliation(s)
- John Masani Nduko
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo, 060-8628, Japan
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Volodina E, Schürmann M, Lindenkamp N, Steinbüchel A. Characterization of propionate CoA-transferase from Ralstonia eutropha H16. Appl Microbiol Biotechnol 2013; 98:3579-89. [PMID: 24057402 DOI: 10.1007/s00253-013-5222-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/24/2013] [Accepted: 08/29/2013] [Indexed: 11/30/2022]
Abstract
In this study, a propionate CoA-transferase (H16_A2718; EC 2.8.3.1) from Ralstonia eutropha H16 (Pct(Re)) was characterized in detail. Glu342 was identified as catalytically active amino acid residue via site-directed mutagenesis. Activity of Pct(Re) was irreversibly lost after the treatment with NaBH₄ in the presence of acetyl-CoA as it is shown for all CoA-transferases from class I, thereby confirming the formation of the covalent enzyme-CoA intermediate by Pct(Re). In addition to already known CoA acceptors for Pct Re such as 3-hydroxypropionate, 3-hydroxybutyrate, acrylate, succinate, lactate, butyrate, crotonate and 4-hydroxybutyrate, it was found that glycolate, chloropropionate, acetoacetate, valerate, trans-2,3-pentenoate, isovalerate, hexanoate, octanoate and trans-2,3-octenoate formed also corresponding CoA-thioesters after incubation with acetyl-CoA and Pct(Re). Isobutyrate was found to be preferentially used as CoA acceptor amongst other carboxylates tested in this study. In contrast, no products were detected with acetyl-CoA and formiate, bromopropionate, glycine, pyruvate, 2-hydroxybutyrate, malonate, fumarate, itaconate, β-alanine, γ-aminobutyrate, levulate, glutarate or adipate as potential CoA acceptor. Amongst CoA donors, butyryl-CoA, crotonyl-CoA, 3-hydroxybutyryl-CoA, isobutyryl-CoA, succinyl-CoA and valeryl-CoA apart from already known propionyl-CoA and acetyl-CoA could also donate CoA to acetate. The highest rate of the reaction was observed with 3-hydroxybutyryl-CoA (2.5 μmol mg⁻¹ min⁻¹). K(m) values for propionyl-CoA, acetyl-CoA, acetate and 3-hydroxybutyrate were 0.3, 0.6, 4.5 and 4.3 mM, respectively. The rather broad substrate range might be a good starting point for enzyme engineering approaches and for the application of Pct(Re) in biotechnological polyester production.
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Affiliation(s)
- Elena Volodina
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstraße 3, 48149, Münster, Germany
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Matsumoto K, Taguchi S. Biosynthetic polyesters consisting of 2-hydroxyalkanoic acids: current challenges and unresolved questions. Appl Microbiol Biotechnol 2013; 97:8011-21. [DOI: 10.1007/s00253-013-5120-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 07/10/2013] [Accepted: 07/10/2013] [Indexed: 11/30/2022]
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Jin YX, Shi LH, Kawata Y. Metabolomics-based component profiling of Halomonas sp. KM-1 during different growth phases in poly(3-hydroxybutyrate) production. BIORESOURCE TECHNOLOGY 2013; 140:73-79. [PMID: 23672941 DOI: 10.1016/j.biortech.2013.04.059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 06/02/2023]
Abstract
To investigate the relationship between the production of poly(3-hydroxybutyrate) (PHB) and metabolic changes during different growth phases, a non-sterile batch fermentation process involving an alkalophilic and halophilic bacterium, Halomonas sp. KM-1, was used. Intracellular metabolites were analyzed using gas chromatography-mass spectrometry to characterize the metabolic profile. Significant changes relating to PHB production were observed in the TCA cycle, lipid-synthesis and amino acid biosynthetic pathways were found to shift dramatically between the exponential growth and stationary phases. During the stationary phase, 17 metabolites were upregulated and a cell dry mass of 17.8 g/L that included 44.8% PHB was observed at 24h in 5% glucose-supplemented cultures, whereas 11 metabolites were upregulated and a cell dry mass of 38.4 g/L that included 73.7% PHB was observed at 36 h in 10% glucose-supplemented cultures. This study provides pattern analysis of metabolite regulation during PHB accumulation, indicating that multicomponent and phase-specific mechanisms are involved.
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Affiliation(s)
- You-Xun Jin
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka, Ikeda, Osaka 563-8577, Japan
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A propionate CoA-transferase of Ralstonia eutropha H16 with broad substrate specificity catalyzing the CoA thioester formation of various carboxylic acids. Appl Microbiol Biotechnol 2012; 97:7699-709. [PMID: 23250223 DOI: 10.1007/s00253-012-4624-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 11/22/2012] [Accepted: 11/26/2012] [Indexed: 10/27/2022]
Abstract
In this study, we have investigated a propionate CoA-transferase (Pct) homologue encoded in the genome of Ralstonia eutropha H16. The corresponding gene has been cloned into the vector pET-19b to yield a histidine-tagged enzyme which was expressed in Escherichia coli BL21 (DE3). After purification, high-performance liquid chromatography/mass spectrometry (HPLC/MS) analyses revealed that the enzyme exhibits a broad substrate specificity for carboxylic acids. The formation of the corresponding CoA-thioesters of acetate using propionyl-CoA as CoA donor, and of propionate, butyrate, 3-hydroxybutyrate, 3-hydroxypropionate, crotonate, acrylate, lactate, succinate and 4-hydroxybutyrate using acetyl-CoA as CoA donor could be shown. According to the substrate specificity, the enzyme can be allocated in the family I of CoA-transferases. The apparent molecular masses as determined by gel filtration and detected by SDS polyacrylamide gel electrophoresis were 228 and 64 kDa, respectively, and point to a quaternary structure of the native enzyme (α4). The enzyme exhibited similarities in sequence and structure to the well investigated Pct of Clostridium propionicum. It does not contain the typical conserved (S)ENG motif, but the derived motif sequence EXG with glutamate 342 to be, most likely, the catalytic residue. Due to the homo-oligomeric structure and the sequence differences with the subclasses IA-C of family I CoA-transferases, a fourth subclass of family I is proposed, comprising - amongst others - the Pcts of R. eutropha H16 and C. propionicum. A markerless precise-deletion mutant R. eutropha H16∆pct was generated. The growth and accumulation behaviour of this mutant on gluconate, gluconate plus 3,3'-dithiodipropionic acid (DTDP), acetate and propionate was investigated but resulted in no observable phenotype. Both, the wild type and the mutant showed the same growth and storage behaviour with these carbon sources. It is probable that R. eutropha H16 is upregulating other CoA-transferase(s) or CoA-synthetase(s), thereby compensating for the lacking Pct. The ability of R. eutropha H16 to substitute absent enzymes by isoenzymes has been already shown in different other studies in the past.
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