1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Zhang L, Jiang Z, Tsui TH, Loh KC, Dai Y, Tong YW. A Review on Enhancing Cupriavidus necator Fermentation for Poly(3-hydroxybutyrate) (PHB) Production From Low-Cost Carbon Sources. Front Bioeng Biotechnol 2022; 10:946085. [PMID: 35928944 PMCID: PMC9343952 DOI: 10.3389/fbioe.2022.946085] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
In the context of a circular economy, bioplastic production using biodegradable materials such as poly(3-hydroxybutyrate) (PHB) has been proposed as a promising solution to fundamentally solve the disposal issue of plastic waste. PHB production techniques through fermentation of PHB-accumulating microbes such as Cupriavidus necator have been revolutionized over the past several years with the development of new strategies such as metabolic engineering. This review comprehensively summarizes the latest PHB production technologies via Cupriavidus necator fermentation. The mechanism of the biosynthesis pathway for PHB production was first assessed. PHB production efficiencies of common carbon sources, including food waste, lignocellulosic materials, glycerol, and carbon dioxide, were then summarized and critically analyzed. The key findings in enhancing strategies for PHB production in recent years, including pre-treatment methods, nutrient limitations, feeding optimization strategies, and metabolism engineering strategies, were summarized. Furthermore, technical challenges and future prospects of strategies for enhanced production efficiencies of PHB were also highlighted. Based on the overview of the current enhancing technologies, more pilot-scale and larger-scale tests are essential for future implementation of enhancing strategies in full-scale biogas plants. Critical analyses of various enhancing strategies would facilitate the establishment of more sustainable microbial fermentation systems for better waste management and greater efficiency of PHB production.
Collapse
Affiliation(s)
- Le Zhang
- NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore
- Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, Singapore
| | - Zicheng Jiang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
| | - To-Hung Tsui
- NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore
- Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, Singapore
| | - Kai-Chee Loh
- Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
| | - Yanjun Dai
- Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, Singapore
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yen Wah Tong
- NUS Environmental Research Institute, National University of Singapore, Singapore, Singapore
- Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), Singapore, Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
- *Correspondence: Yen Wah Tong,
| |
Collapse
|
3
|
Saito S, Imai R, Miyahara Y, Nakagawa M, Orita I, Tsuge T, Fukui T. Biosynthesis of Poly(3-hydroxybutyrate- co-3-hydroxyhexanoate) From Glucose by Escherichia coli Through Butyryl-CoA Formation Driven by Ccr-Emd Combination. Front Bioeng Biotechnol 2022; 10:888973. [PMID: 35646875 PMCID: PMC9134075 DOI: 10.3389/fbioe.2022.888973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/11/2022] [Indexed: 11/29/2022] Open
Abstract
Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] is a practical kind of bacterial polyhydroxyalkanoates (PHAs). A previous study has established an artificial pathway for the biosynthesis of P(3HB-co-3HHx) from structurally unrelated sugars in Ralstonia eutropha, in which crotonyl-CoA carboxylase/reductase (Ccr) and ethylmalonyl-CoA decarboxylase (Emd) are a key combination for generation of butyryl-CoA and the following chain elongation. This study focused on the installation of the artificial pathway into Escherichia coli. The recombinant strain of E. coli JM109 harboring 11 heterologous genes including Ccr and Emd produced P(3HB-co-3HHx) composed of 14 mol% 3HHx with 41 wt% of dry cellular weight from glucose. Further investigations revealed that the C6 monomer (R)-3HHx-CoA was not supplied by (R)-specific reduction of 3-oxohexanoyl-CoA but by (R)-specific hydration of 2-hexenoyl-CoA formed through reverse β-oxidation after the elongation from C4 to C6. While contribution of the reverse β-oxidation to the conversion of the C4 intermediates was very limited, crotonyl-CoA, a precursor of butyryl-CoA, was generated by dehydration of (R)-3HB-CoA. Several modifications previously reported for enhancement of bioproduction in E. coli were examined for the copolyester synthesis. Elimination of the global regulator Cra or PdhR as well as the block of acetate formation resulted in poor PHA synthesis. The strain lacking RNase G accumulated more PHA but with almost no 3HHx unit. Introduction of the phosphite oxidation system for regeneration of NADPH led to copolyester synthesis with the higher cellular content and higher 3HHx composition by two-stage cultivation with phosphite than those in the absence of phosphite.
Collapse
Affiliation(s)
- Shu Saito
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Ryu Imai
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Yuki Miyahara
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Mari Nakagawa
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Izumi Orita
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Takeharu Tsuge
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Toshiaki Fukui
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| |
Collapse
|
4
|
Orrego AH, Andrés-Sanz D, Velasco-Lozano S, Sanchez-Costa M, Berenguer J, Guisan JM, Rocha-Martin J, López-Gallego F. Self-sufficient asymmetric reduction of β-ketoesters catalysed by a novel and robust thermophilic alcohol dehydrogenase co-immobilised with NADH. Catal Sci Technol 2021; 11:3217-3230. [PMID: 34094502 PMCID: PMC8111925 DOI: 10.1039/d1cy00268f] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 02/25/2021] [Indexed: 12/04/2022]
Abstract
β-Hydroxyesters are essential building blocks utilised by the pharmaceutical and food industries in the synthesis of functional products. Beyond the conventional production methods based on chemical catalysis or whole-cell synthesis, the asymmetric reduction of β-ketoesters with cell-free enzymes is gaining relevance. To this end, a novel thermophilic (S)-3-hydroxybutyryl-CoA dehydrogenase from Thermus thermophilus HB27 (Tt27-HBDH) has been expressed, purified and biochemically characterised, determining its substrate specificity towards β-ketoesters and its dependence on NADH as a cofactor. The immobilization of Tt27-HBDH on agarose macroporous beads and its subsequent coating with polyethyleneimine has been found the best strategy to increase the stability and workability of the heterogeneous biocatalyst. Furthermore, we have embedded NADH in the cationic layer attached to the porous surface of the carrier. Since Tt27-HBDH catalyses cofactor recycling through 2-propanol oxidation, we achieve a self-sufficient heterogeneous biocatalyst where NADH is available for the immobilised enzymes but its lixiviation to the reaction bulk is avoided. Taking advantage of the autofluorescence of NADH, we demonstrate the activity of the enzyme towards the immobilised cofactor through single-particle analysis. Finally, we tested the operational stability in the asymmetric reduction of β-ketoesters in batch, succeeding in the reuse of both the enzyme and the co-immobilised cofactor up to 10 reaction cycles.
Collapse
Affiliation(s)
- Alejandro H Orrego
- Department of Biocatalysis, Institute of Catalysis and Petrochemistry (ICP), CSIC Campus UAM, Cantoblanco 28049 Madrid Spain
- Department of Molecular Biology, Universidad Autónoma de Madrid, Center for Molecular Biology Severo-Ochoa (UAM-CSIC) Nicolás Cabrera 1 28049 Madrid Spain
- Heterogeneous Biocatalysis Laboratory, Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA) Paseo de Miramón 182 Donostia San Sebastián Spain
| | - Daniel Andrés-Sanz
- Heterogeneous Biocatalysis Laboratory, Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA) Paseo de Miramón 182 Donostia San Sebastián Spain
| | - Susana Velasco-Lozano
- Heterogeneous Biocatalysis Laboratory, Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA) Paseo de Miramón 182 Donostia San Sebastián Spain
| | - Mercedes Sanchez-Costa
- Department of Molecular Biology, Universidad Autónoma de Madrid, Center for Molecular Biology Severo-Ochoa (UAM-CSIC) Nicolás Cabrera 1 28049 Madrid Spain
| | - José Berenguer
- Department of Molecular Biology, Universidad Autónoma de Madrid, Center for Molecular Biology Severo-Ochoa (UAM-CSIC) Nicolás Cabrera 1 28049 Madrid Spain
| | - José M Guisan
- Department of Biocatalysis, Institute of Catalysis and Petrochemistry (ICP), CSIC Campus UAM, Cantoblanco 28049 Madrid Spain
| | - Javier Rocha-Martin
- Department of Biocatalysis, Institute of Catalysis and Petrochemistry (ICP), CSIC Campus UAM, Cantoblanco 28049 Madrid Spain
| | - Fernando López-Gallego
- Heterogeneous Biocatalysis Laboratory, Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA) Paseo de Miramón 182 Donostia San Sebastián Spain
- IKERBASQUE, Basque Foundation for Science María Díaz de Haro 3 48013 Bilbao Spain
| |
Collapse
|
5
|
Revealing the Metabolic Flexibility of " Candidatus Accumulibacter phosphatis" through Redox Cofactor Analysis and Metabolic Network Modeling. Appl Environ Microbiol 2020; 86:AEM.00808-20. [PMID: 33008826 DOI: 10.1128/aem.00808-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 09/21/2020] [Indexed: 12/27/2022] Open
Abstract
Environmental fluctuations in the availability of nutrients lead to intricate metabolic strategies. "Candidatus Accumulibacter phosphatis," a polyphosphate-accumulating organism (PAO) responsible for enhanced biological phosphorus removal (EBPR) from wastewater treatment systems, is prevalent in aerobic/anaerobic environments. While the overall metabolic traits of these bacteria are well described, the nonavailability of isolates has led to controversial conclusions on the metabolic pathways used. In this study, we experimentally determined the redox cofactor preferences of different oxidoreductases in the central carbon metabolism of a highly enriched "Ca Accumulibacter phosphatis" culture. Remarkably, we observed that the acetoacetyl coenzyme A reductase engaged in polyhydroxyalkanoate (PHA) synthesis is NADH preferring instead of showing the generally assumed NADPH dependency. This allows rethinking of the ecological role of PHA accumulation as a fermentation product under anaerobic conditions and not just a stress response. Based on previously published metaomics data and the results of enzymatic assays, a reduced central carbon metabolic network was constructed and used for simulating different metabolic operating modes. In particular, scenarios with different acetate-to-glycogen consumption ratios were simulated, which demonstrated optima using different combinations of glycolysis, glyoxylate shunt, or branches of the tricarboxylic acid (TCA) cycle. Thus, optimal metabolic flux strategies will depend on the environment (acetate uptake) and on intracellular storage compound availability (polyphosphate/glycogen). This NADH-related metabolic flexibility is enabled by the NADH-driven PHA synthesis. It allows for maintaining metabolic activity under various environmental substrate conditions, with high carbon conservation and lower energetic costs than for NADPH-dependent PHA synthesis. Such (flexible) metabolic redox coupling can explain the competitiveness of PAOs under oxygen-fluctuating environments.IMPORTANCE Here, we demonstrate how microbial storage metabolism can adjust to a wide range of environmental conditions. Such flexibility generates a selective advantage under fluctuating environmental conditions. It can also explain the different observations reported in PAO literature, including the capacity of "Ca Accumulibacter phosphatis" to act like glycogen-accumulating organisms (GAOs). These observations stem from slightly different experimental conditions, and controversy arises only when one assumes that metabolism can operate only in a single mode. Furthermore, we also show how the study of metabolic strategies is possible when combining omics data with functional cofactor assays and modeling. Genomic information can only provide the potential of a microorganism. The environmental context and other complementary approaches are still needed to study and predict the functional expression of such metabolic potential.
Collapse
|
6
|
Olavarria K, Carnet A, van Renselaar J, Quakkelaar C, Cabrera R, Guedes da Silva L, Smids AL, Villalobos PA, van Loosdrecht MCM, Wahl SA. An NADH preferring acetoacetyl-CoA reductase is engaged in poly-3-hydroxybutyrate accumulation in Escherichia coli. J Biotechnol 2020; 325:207-216. [PMID: 33122026 DOI: 10.1016/j.jbiotec.2020.10.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/16/2020] [Accepted: 10/18/2020] [Indexed: 01/08/2023]
Abstract
Oxygen supply implies higher production cost and reduction of maximum theoretical yields. Thus, generation of fermentation products is more cost-effective. Aiming to find a key piece for the production of (poly)-3-hydroxybutyrate (PHB) as a fermentation product, here we characterize an acetoacetyl-CoA reductase, isolated from a Candidatus Accumulibacter phosphatis-enriched mixed culture, showing a (kcatNADH/KMNADH)/(kcatNADPH/KMNADPH)>500. Further kinetic analyses indicate that, at physiological concentrations, this enzyme clearly prefers NADH, presenting the strongest NADH preference so far observed among the acetoacetyl-CoA reductases. Structural and kinetic analyses indicate that residues between E37 and P41 have an important role for the observed NADH preference. Moreover, an operon was assembled combining the phaCA genes from Cupriavidus necator and the gene encoding for this NADH-preferring acetoacetyl-CoA reductase. Escherichia coli cells expressing that assembled operon showed continuous accumulation of PHB under oxygen limiting conditions and PHB titer increased when decreasing the specific oxygen consumption rate. Taken together, these results show that it is possible to generate PHB as a fermentation product in E. coli, opening opportunities for further protein/metabolic engineering strategies envisioning a more efficient anaerobic production of PHB.
Collapse
Affiliation(s)
- Karel Olavarria
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - Alexandre Carnet
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - Joachim van Renselaar
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - Caspar Quakkelaar
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - Ricardo Cabrera
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Región Metropolitana, Chile.
| | - Leonor Guedes da Silva
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - Aron L Smids
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - Pablo Andres Villalobos
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Región Metropolitana, Chile.
| | - Mark C M van Loosdrecht
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| | - S Aljoscha Wahl
- Departement Biotechnologie, Faculteit Technische Natuurwetenschappen, Technische Universiteit Delft, Van der Maasweg 9, 2629 HZ, Netherlands.
| |
Collapse
|
7
|
Velázquez-Sánchez C, Espín G, Peña C, Segura D. The Modification of Regulatory Circuits Involved in the Control of Polyhydroxyalkanoates Metabolism to Improve Their Production. Front Bioeng Biotechnol 2020; 8:386. [PMID: 32426348 PMCID: PMC7204398 DOI: 10.3389/fbioe.2020.00386] [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: 12/07/2019] [Accepted: 04/07/2020] [Indexed: 11/13/2022] Open
Abstract
Poly-(3-hydroxyalkanoates) (PHAs) are bacterial carbon and energy storage compounds. These polymers are synthesized under conditions of nutritional imbalance, where a nutrient is growth-limiting while there is still enough carbon source in the medium. On the other side, the accumulated polymer is mobilized under conditions of nutrient accessibility or by limitation of the carbon source. Thus, it is well known that the accumulation of PHAs is affected by the availability of nutritional resources and this knowledge has been used to establish culture conditions favoring high productivities. In addition to this effect of the metabolic status on PHAs accumulation, several genetic regulatory networks have been shown to drive PHAs metabolism, so the expression of the PHAs genes is under the influence of global or specific regulators. These regulators are thought to coordinate PHAs synthesis and mobilization with the rest of bacterial physiology. While the metabolic and biochemical knowledge related to the biosynthesis of these polymers has led to the development of processes in bioreactors for high-level production and also to the establishment of strategies for metabolic engineering for the synthesis of modified biopolymers, the use of knowledge related to the regulatory circuits controlling PHAs metabolism for strain improvement is scarce. A better understanding of the genetic control systems involved could serve as the foundation for new strategies for strain modification in order to increase PHAs production or to adjust the chemical structure of these biopolymers. In this review, the regulatory systems involved in the control of PHAs metabolism are examined, with emphasis on those acting at the level of expression of the enzymes involved and their potential modification for strain improvement, both for higher titers, or manipulation of polymer properties. The case of the PHAs producer Azotobacter vinelandii is taken as an example of the complexity and variety of systems controlling the accumulation of these interesting polymers in response to diverse situations, many of which could be engineered to improve PHAs production.
Collapse
Affiliation(s)
- Claudia Velázquez-Sánchez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Carlos Peña
- Departamento Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Daniel Segura
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| |
Collapse
|
8
|
Modification of acetoacetyl-CoA reduction step in Ralstonia eutropha for biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from structurally unrelated compounds. Microb Cell Fact 2019; 18:147. [PMID: 31466527 PMCID: PMC6716841 DOI: 10.1186/s12934-019-1197-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/22/2019] [Indexed: 12/24/2022] Open
Abstract
Background Poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)] is a bacterial polyester with high biodegradability, even in marine environments. Ralstonia eutropha has been engineered for the biosynthesis of P(3HB-co-3HHx) from vegetable oils, but its production from structurally unrelated carbon sources remains unsatisfactory. Results Ralstonia eutropha strains capable of synthesizing P(3HB-co-3HHx) from not only fructose but also glucose and glycerol were constructed by integrating previously established engineering strategies. Further modifications were made at the acetoacetyl-CoA reduction step determining flux distribution responsible for the copolymer composition. When the major acetoacetyl-CoA reductase (PhaB1) was replaced by a low-activity paralog (PhaB2) or enzymes for reverse β-oxidation, copolyesters with high 3HHx composition were efficiently synthesized from glucose, possibly due to enhanced formation of butyryl-CoA from acetoacetyl-CoA via (S)-3HB-CoA. P(3HB-co-3HHx) composed of 7.0 mol% and 12.1 mol% 3HHx fractions, adequate for practical applications, were produced at cellular contents of 71.4 wt% and 75.3 wt%, respectively. The replacement by low-affinity mutants of PhaB1 had little impact on the PHA biosynthesis on glucose, but slightly affected those on fructose, suggesting altered metabolic regulation depending on the sugar-transport machinery. PhaB1 mostly acted in the conversion of acetoacetyl-CoA when the cells were grown on glycerol, as copolyester biosynthesis was severely impaired by the lack of phaB1. Conclusions The present results indicate the importance of flux distribution at the acetoacetyl-CoA node in R. eutropha for the biosynthesis of the PHA copolyesters with regulated composition from structurally unrelated compounds.
Collapse
|
9
|
Yamaguchi T, Narsico J, Kobayashi T, Inoue A, Ojima T. Production of poly(3-hydroyxybutylate) by a novel alginolytic bacterium Hydrogenophaga sp. strain UMI-18 using alginate as a sole carbon source. J Biosci Bioeng 2019; 128:203-208. [DOI: 10.1016/j.jbiosc.2019.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/15/2019] [Accepted: 02/15/2019] [Indexed: 01/01/2023]
|
10
|
Segawa M, Wen C, Orita I, Nakamura S, Fukui T. Two NADH-dependent (S)-3-hydroxyacyl-CoA dehydrogenases from polyhydroxyalkanoate-producing Ralstonia eutropha. J Biosci Bioeng 2018; 127:294-300. [PMID: 30243533 DOI: 10.1016/j.jbiosc.2018.08.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/20/2018] [Accepted: 08/22/2018] [Indexed: 12/28/2022]
Abstract
Ralstonia eutropha H16 contains both NADH- and NADPH-dependent reduction activities to acetoacetyl-CoA, and the NADPH-dependent activity is mediated by PhaB paralogs with (R)-stereospecificity providing (R)-3-hydroxybutyryl (3HB)-CoA monomer for poly((R)-3-hydroxybutyrate) synthesis. In contrast, the gene encoding the NADH-dependent enzyme has not been identified to date. This study focused on the NADH-dependent dehydrogenase with (S)-stereospecificity in R. eutropha, as the (S)-specific reduction of acetoacetyl-CoA potentially competed with the polyester biosynthesis via (R)-3HB-CoA. The NADH-dependent reduction activity decreased to one-half when the gene for H16_A0282 (PaaH1), one of two homologs of clostridial NADH-3HB-CoA dehydrogenase, was deleted. The enzyme responsible for the remaining activity was partially purified and identified as H16_A0602 (Had) belonging to a different family from PaaH1. Gene disruption analysis elucidated that most of the NADH-dependent activity was mediated by PaaH1 and Had. The kinetic analysis using the recombinant enzymes indicated that PaaH1 and Had were both NADH-dependent 3-hydroxyacyl-CoA dehydrogenases with rather broad substrate specificity to 3-oxoacyl-CoAs of C4 to C8. The deletion of had in the R. eutropha strain previously engineered for biosynthesis of poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) led to decrease in the C6 composition of the copolyester synthesized from soybean oil, suggesting the role of Had in (S)-specific reduction of 3-oxohexanoyl-CoA with reverse β-oxidation direction. Crotonase ((S)-specific enoyl-CoA hydratase) in R. eutropha H16 was also partially purified and identified as H16_A3307.
Collapse
Affiliation(s)
- Mutsumi Segawa
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Cheng Wen
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Izumi Orita
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Satoshi Nakamura
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Toshiaki Fukui
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
| |
Collapse
|
11
|
Malinich EA, Bauer CE. Transcriptome analysis of Azospirillum brasilense vegetative and cyst states reveals large-scale alterations in metabolic and replicative gene expression. Microb Genom 2018; 4. [PMID: 30058999 PMCID: PMC6159551 DOI: 10.1099/mgen.0.000200] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Several Gram-negative soil bacteria have the ability to differentiate into dormant cysts when faced with harsh environmental conditions. For example, when challenged with nutrient deprivation or desiccation, the plant-growth-promoting bacterium Azospirillum brasilense differentiates from a replicative and motile rod-shaped vegetative cell into a non-motile dormant spherical cyst. Currently, little is known about either the metabolic differences that exist between vegetative and cyst cell types, or about aspects of cyst physiology that allow dormant cells to survive harsh conditions. Here we compared transcriptomic profiles of vegetative and encysted A. brasilense. We observed that approximately one fifth of the A. brasilense transcriptome undergoes changes in expression between replicative vegetative cells and non-replicative cysts. A dramatic alteration in expression of genes involved in cell wall or cell membrane biogenesis was observed, which is congruent with changes in exopolysaccharide and lipid composition that occur between these cell types. Encysted cells also exhibited repressed mRNA abundance of genes involved in amino acid biosynthesis, ribosomal biogenesis and translation. We further observed that cysts create an anaerobic/micro-aerobic environment, as evidenced by repressed expression of oxidative phosphorylation genes coupled with increased expression of nitrate/nitrite reduction and nitrogen fixation genes.
Collapse
Affiliation(s)
| | - Carl E Bauer
- 2Department of Biochemistry, Indiana University Bloomington, Simon Hall MSB, Bloomington, IN 47405-7003, USA
| |
Collapse
|
12
|
Miyahara Y, Oota M, Tsuge T. NADPH supply for poly(3-hydroxybutyrate) synthesis concomitant with enzymatic oxidation of phosphite. J Biosci Bioeng 2018; 126:764-768. [PMID: 29910188 DOI: 10.1016/j.jbiosc.2018.05.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 01/07/2023]
Abstract
Acetoacetyl-CoA reductase (PhaB), involved in poly(3-hydroxybutyrate) [P(3HB)] biosynthesis, requires the coenzyme NADPH as a reducing agent. In this study, the effect of NADPH supply on P(3HB) production was investigated in vitro and in vivo using a phosphite dehydrogenase double mutant (PtxDEAAR), which catalyzes oxidation of phosphite to phosphate with the generation of NADH and NADPH. In an in vitro assay using purified enzymes, P(3HB) polymerization was observed only when phosphite and PtxDEAAR were present, confirming that NADPH was supplied to PhaB. In an in vivo assay using Escherichia coli as a production host for P(3HB), the presence of phosphite and PtxDEAAR did not influence the yield of P(3HB) under normal growth conditions. However, P(3HB) yield increased 3.2-fold in non-growing E. coli cells compared to the control, suggesting that PtxDEAAR-mediated NADPH generation is coupled with P(3HB) biosynthesis. This study confirmed the use of PtxDEAAR for supplying NADPH during P(3HB) synthesis in vitro and in vivo.
Collapse
Affiliation(s)
- Yuki Miyahara
- Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Mino Oota
- Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Takeharu Tsuge
- Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan; Department of Materials Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
| |
Collapse
|
13
|
He P, Han W, Shao L, Lü F. One-step production of C6-C8 carboxylates by mixed culture solely grown on CO. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:4. [PMID: 29339973 PMCID: PMC5761104 DOI: 10.1186/s13068-017-1005-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 12/23/2017] [Indexed: 05/29/2023]
Abstract
BACKGROUND This study aimed at producing C6-C8 medium-chain carboxylates (MCCAs) directly from gaseous CO using mixed culture. The yield and C2-C8 product composition were investigated when CO was continuously fed with gradually increasing partial pressure. RESULTS The maximal concentrations of n-caproate, n-heptylate, and n-caprylate were 1.892, 1.635, and 1.033 mmol L-1, which were achieved at the maximal production rates of 0.276, 0.442, and 0.112 mmol L-1 day-1, respectively. Microbial analysis revealed that long-term acclimation and high CO partial pressure were important to establish a CO-tolerant and CO-utilizing chain-elongating microbiome, rich in Acinetobacter, Alcaligenes, and Rhodobacteraceae and capable of forming MCCAs solely from CO. CONCLUSIONS These results demonstrated that carboxylate and syngas platform could be integrated in a shared growth vessel, and could be a promising one-step technique to convert gaseous syngas to preferable liquid biochemicals, thereby avoiding the necessity to coordinate syngas fermentation to short-chain carboxylates and short-to-medium-chain elongation. Thus, this method could provide an alternative solution for the utilization of waste-derived syngas and expand the resource of promising biofuels.
Collapse
Affiliation(s)
- Pinjing He
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 People’s Republic of China
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 People’s Republic of China
- Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development of P. R. China (MOHURD), Shanghai, 200092 People’s Republic of China
| | - Wenhao Han
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 People’s Republic of China
| | - Liming Shao
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 People’s Republic of China
- Centre for the Technology Research and Training on Household Waste in Small Towns & Rural Area, Ministry of Housing and Urban–Rural Development of P. R. China (MOHURD), Shanghai, 200092 People’s Republic of China
| | - Fan Lü
- State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092 People’s Republic of China
- Institute of Waste Treatment and Reclamation, Tongji University, Shanghai, 200092 People’s Republic of China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092 People’s Republic of China
| |
Collapse
|
14
|
Sacomboio ENM, Kim EYS, Ruchaud Correa HL, Bonato P, de Oliveira Pedrosa F, de Souza EM, Chubatsu LS, Müller-Santos M. The transcriptional regulator NtrC controls glucose-6-phosphate dehydrogenase expression and polyhydroxybutyrate synthesis through NADPH availability in Herbaspirillum seropedicae. Sci Rep 2017; 7:13546. [PMID: 29051509 PMCID: PMC5648810 DOI: 10.1038/s41598-017-12649-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 09/12/2017] [Indexed: 11/09/2022] Open
Abstract
The NTR system is the major regulator of nitrogen metabolism in Bacteria. Despite its broad and well-known role in the assimilation, biosynthesis and recycling of nitrogenous molecules, little is known about its role in carbon metabolism. In this work, we present a new facet of the NTR system in the control of NADPH concentration and the biosynthesis of molecules dependent on reduced coenzyme in Herbaspirillum seropedicae SmR1. We demonstrated that a ntrC mutant strain accumulated high levels of polyhydroxybutyrate (PHB), reaching levels up to 2-fold higher than the parental strain. In the absence of NtrC, the activity of glucose-6-phosphate dehydrogenase (encoded by zwf) increased by 2.8-fold, consequently leading to a 2.1-fold increase in the NADPH/NADP+ ratio. A GFP fusion showed that expression of zwf is likewise controlled by NtrC. The increase in NADPH availability stimulated the production of polyhydroxybutyrate regardless the C/N ratio in the medium. The mutant ntrC was more resistant to H2O2 exposure and controlled the propagation of ROS when facing the oxidative condition, a phenotype associated with the increase in PHB content.
Collapse
Affiliation(s)
- Euclides Nenga Manuel Sacomboio
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Edson Yu Sin Kim
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Henrique Leonardo Ruchaud Correa
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Paloma Bonato
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Fabio de Oliveira Pedrosa
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Emanuel Maltempi de Souza
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Leda Satie Chubatsu
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Marcelo Müller-Santos
- Department of Biochemistry and Molecular Biology, Laboratory of Nitrogen Fixation, Federal University of Paraná (UFPR), Curitiba, Brazil.
| |
Collapse
|
15
|
Zamakhaeva SA, Fedorov DN, Trotsenko YA. Methylotrophic producers of bioplastics (Review). APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817040147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
16
|
Understanding the physiological roles of polyhydroxybutyrate (PHB) in Rhodospirillum rubrum S1 under aerobic chemoheterotrophic conditions. Appl Microbiol Biotechnol 2016; 100:8901-12. [PMID: 27480532 DOI: 10.1007/s00253-016-7711-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 06/28/2016] [Indexed: 10/21/2022]
Abstract
Polyhydroxybutyrate (PHB) is an important biopolymer accumulated by bacteria and associated with cell survival and stress response. Here, we make two surprising findings in the PHB-accumulating species Rhodospirillum rubrum S1. We first show that the presence of PHB promotes the increased assimilation of acetate preferentially into biomass rather than PHB. When R. rubrum is supplied with (13)C-acetate as a PHB precursor, 83.5 % of the carbon in PHB comes from acetate. However, only 15 % of the acetate ends up in PHB with the remainder assimilated as bacterial biomass. The PHB-negative mutant of R. rubrum assimilates 2-fold less acetate into biomass compared to the wild-type strain. Acetate assimilation proceeds via the ethylmalonyl-CoA pathway with (R)-3-hydroxybutyrate as a common intermediate with the PHB pathway. Secondly, we show that R. rubrum cells accumulating PHB have reduced ribulose 1,5-bisphosphate carboxylase (RuBisCO) activity. RuBisCO activity reduces 5-fold over a 36-h period after the onset of PHB. In contrast, a PHB-negative mutant maintains the same level of RuBisCO activity over the growth period. Since RuBisCO controls the redox potential in R. rubrum, PHB likely replaces RuBisCO in this role. R. rubrum is the first bacterium found to express RuBisCO under aerobic chemoheterotrophic conditions.
Collapse
|
17
|
Effect of nitrogen and/or oxygen concentration on poly(3-hydroxybutyrate) accumulation by Halomonas boliviensis. Bioprocess Biosyst Eng 2016; 39:1365-74. [DOI: 10.1007/s00449-016-1612-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/19/2016] [Indexed: 11/27/2022]
|
18
|
Enoyl-CoA hydratase mediates polyhydroxyalkanoate mobilization in Haloferax mediterranei. Sci Rep 2016; 6:24015. [PMID: 27052994 PMCID: PMC4823750 DOI: 10.1038/srep24015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 03/17/2016] [Indexed: 02/08/2023] Open
Abstract
Although polyhydroxyalkanoate (PHA) accumulation and mobilization are one of the most general mechanisms for haloarchaea to adapt to the hypersaline environments with changeable carbon sources, the PHA mobilization pathways are still not clear for any haloarchaea. In this study, the functions of five putative (R)-specific enoyl-CoA hydratases (R-ECHs) in Haloferax mediterranei, named PhaJ1 to PhaJ5, respectively, were thoroughly investigated. Through gene deletion and complementation, we demonstrated that only certain of these ECHs had a slight contribution to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biosynthesis. But significantly, PhaJ1, the only R-ECH that is associated with PHA granules, was shown to be involved in PHA mobilization in this haloarchaeon. PhaJ1 catalyzes the dehydration of (R)-3-hydroxyacyl-CoA, the common product of PHA degradation, to enoyl-CoA, the intermediate of the β-oxidation cycle, thus could link PHA mobilization to β-oxidation pathway in H. mediterranei. This linkage was further indicated from the up-regulation of the key genes of β-oxidation under the PHA mobilization condition, as well as the obvious inhibition of PHA degradation upon inhibition of the β-oxidation pathway. Interestingly, 96% of phaJ-containing haloarchaeal species possess both phaC (encoding PHA synthase) and the full set genes of β-oxidation, implying that the mobilization of carbon storage in PHA through the β-oxidation cycle would be general in haloarchaea.
Collapse
|
19
|
Heinrich D, Raberg M, Steinbüchel A. Synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from unrelated carbon sources in engineered Rhodospirillum rubrum. FEMS Microbiol Lett 2015; 362:fnv038. [PMID: 25761750 DOI: 10.1093/femsle/fnv038] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2015] [Indexed: 11/12/2022] Open
Abstract
Different genes encoding pyridine nucleotide transhydrogenases (pntAB, udhA) and acetoacetyl-CoA reductases (phaB) were heterologously overexpressed in Rhodospirillum rubrum S1. A recombinant strain, which harbored the gene encoding the membrane-bound transhydrogenase PntAB from Escherichia coli MG1655 and the phaB1 gene coding for an NADPH-dependent acetoacetyl-CoA reductase from Ralstonia eutropha H16, accumulated poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [Poly(3HB-co-3HV)] with a 3HV fraction of up to 13 mol% from fructose. This was a 13-fold increase of the 3HV content when compared to the wild-type strain. Higher contents of 3HV are known to reduce the brittleness of this polymer, which is advantageous for most applications. The engineered R. rubrum strain was also able to synthesize this industrially relevant copolymer from CO2 and CO from artificial synthesis gas (syngas) with a 3HV content of 56 mol%. The increased incorporation of 3HV was attributed to an excess of propionyl-CoA, which was generated from threonine and related amino acids to compensate for the intracellular redox imbalance resulting from the transhydrogenase reaction. Thereby, our study presents a novel, molecular approach to alter the composition of bacterial PHAs independently from external precursor supply. Moreover, this study also provides a promising production strain for syngas-derived second-generation biopolymers.
Collapse
Affiliation(s)
- Daniel Heinrich
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany
| | - Matthias Raberg
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany; Environmental Sciences Department, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| |
Collapse
|
20
|
Raberg M, Heinrich D, Steinbüchel A. Analysis of PHB Metabolism Applying Tn5 Mutagenesis in Ralstonia eutropha. SPRINGER PROTOCOLS HANDBOOKS 2015. [DOI: 10.1007/8623_2015_110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
21
|
López NI, Pettinari MJ, Nikel PI, Méndez BS. Polyhydroxyalkanoates: Much More than Biodegradable Plastics. ADVANCES IN APPLIED MICROBIOLOGY 2015; 93:73-106. [PMID: 26505689 DOI: 10.1016/bs.aambs.2015.06.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Bacterial polyhydroxyalkanoates (PHAs) are isotactic polymers that play a critical role in central metabolism, as they act as dynamic reservoirs of carbon and reducing equivalents. These polymers have a number of technical applications since they exhibit thermoplastic and elastomeric properties, making them attractive as a replacement of oil-derived materials. PHAs are accumulated under conditions of nutritional imbalance (usually an excess of carbon source with respect to a limiting nutrient, such as nitrogen or phosphorus). The cycle of PHA synthesis and degradation has been recognized as an important physiological feature when these biochemical pathways were originally described, yet its role in bacterial processes as diverse as global regulation and cell survival is just starting to be appreciated in full. In the present revision, the complex regulation of PHA synthesis and degradation at the transcriptional, translational, and metabolic levels are explored by analyzing examples in natural producer bacteria, such as Pseudomonas species, as well as in recombinant Escherichia coli strains. The ecological role of PHAs, together with the interrelations with other polymers and extracellular substances, is also discussed, along with their importance in cell survival, resistance to several types of environmental stress, and planktonic-versus-biofilm lifestyle. Finally, bioremediation and plant growth promotion are presented as examples of environmental applications in which PHA accumulation has successfully been exploited.
Collapse
|
22
|
Eggers J, Steinbüchel A. Impact of Ralstonia eutropha's poly(3-Hydroxybutyrate) (PHB) Depolymerases and Phasins on PHB storage in recombinant Escherichia coli. Appl Environ Microbiol 2014; 80:7702-9. [PMID: 25281380 PMCID: PMC4249218 DOI: 10.1128/aem.02666-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/29/2014] [Indexed: 11/20/2022] Open
Abstract
The model organism for polyhydroxybutyrate (PHB) biosynthesis, Ralstonia eutropha H16, possesses multiple isoenzymes of granules coating phasins as well as of PHB depolymerases, which degrade accumulated PHB under conditions of carbon limitation. In this study, recombinant Escherichia coli BL21(DE3) strains were used to study the impact of selected PHB depolymerases of R. eutropha H16 on the growth behavior and on the amount of accumulated PHB in the absence or presence of phasins. For this purpose, 20 recombinant E. coli BL21(DE3) strains were constructed, which harbored a plasmid carrying the phaCAB operon from R. eutropha H16 to ensure PHB synthesis and a second plasmid carrying different combinations of the genes encoding a phasin and a PHB depolymerase from R. eutropha H16. It is shown in this study that the growth behavior of the respective recombinant E. coli strains was barely affected by the overexpression of the phasin and PHB depolymerase genes. However, the impact on the PHB contents was significantly greater. The strains expressing the genes of the PHB depolymerases PhaZ1, PhaZ2, PhaZ3, and PhaZ7 showed 35% to 94% lower PHB contents after 30 h of cultivation than the control strain. The strain harboring phaZ7 reached by far the lowest content of accumulated PHB (only 2.0% [wt/wt] PHB of cell dry weight). Furthermore, coexpression of phasins in addition to the PHB depolymerases influenced the amount of PHB stored in cells of the respective strains. It was shown that the phasins PhaP1, PhaP2, and PhaP4 are not substitutable without an impact on the amount of stored PHB. In particular, the phasins PhaP2 and PhaP4 seemed to limit the degradation of PHB by the PHB depolymerases PhaZ2, PhaZ3, and PhaZ7, whereas almost no influence of the different phasins was observed if phaZ1 was coexpressed. This study represents an extensive analysis of the impact of PHB depolymerases and phasins on PHB accumulation and provides a deeper insight into the complex interplay of these enzymes.
Collapse
Affiliation(s)
- Jessica Eggers
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms Universität Münster, Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms Universität Münster, Münster, Germany Environmental Sciences Department, King Abdulaziz University, Jeddah, Saudi Arabia
| |
Collapse
|
23
|
(S)-3-hydroxyacyl-CoA dehydrogenase/enoyl-CoA hydratase (FadB') from fatty acid degradation operon of Ralstonia eutropha H16. AMB Express 2014; 4:69. [PMID: 25401070 PMCID: PMC4230905 DOI: 10.1186/s13568-014-0069-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 08/13/2014] [Indexed: 11/12/2022] Open
Abstract
In this study (S)-3-hydroxyacyl-CoA dehydrogenase/enoyl-CoA hydratase (H16_A0461/FadB’, gene ID: 4247876) from one of two active fatty acid degradation operons of Ralstonia eutropha H16 has been heterologously expressed in Escherichia coli, purified as protein possessing a His-Tag and initially characterized. FadB’ is an enzyme with two catalytic domains exhibiting a single monomeric structure and possessing a molecular weight of 86 kDa. The C-terminal part of the enzyme harbors enoyl-CoA hydratase activity and is able to convert trans-crotonyl-CoA to 3-hydroxybutyryl-CoA. The N-terminal part of FadB’ comprises an NAD+ binding site and is responsible for 3-hydroxyacyl-CoA dehydrogenase activity converting (S)-3-hydroxybutyryl-CoA to acetoacetyl-CoA. Enoyl-CoA hydratase activity was detected spectrophotometrically with trans-crotonyl-CoA. (S)-3-Hydroxyacyl-CoA dehydrogenase activity was measured in both directions with acetoacetyl-CoA and 3-hydroxybutyryl-CoA. FadB’ was found to be strictly stereospecific to (S)-3-hydroxybutyryl-CoA and to prefer NAD+. The Km value for acetoacetyl-CoA was 48 μM and Vmax 149 μmol mg−1 min−1. NADP(H) was utilized at a rate of less than 10% in comparison to activity with NAD(H). FadB’ exhibited optimal activity at pH 6–7 and the activity decreased at alkaline and acidic pH values. Acetyl-CoA, propionyl-CoA and CoA were found to have an inhibitory effect on FadB’. This study is a first report on biochemical properties of purified (S)-stereospecific 3-hydroxyacyl-CoA dehydrogenase/enoyl-CoA hydratase with the inverted domain order from R. eutropha H16. In addition to fundamental information about FadB’ and fatty acid metabolism, FadB’ might be also interesting for biotechnological applications.
Collapse
|
24
|
Raberg M, Voigt B, Hecker M, Steinbüchel A. A closer look on the polyhydroxybutyrate- (PHB-) negative phenotype of Ralstonia eutropha PHB-4. PLoS One 2014; 9:e95907. [PMID: 24787649 PMCID: PMC4008487 DOI: 10.1371/journal.pone.0095907] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 04/01/2014] [Indexed: 11/18/2022] Open
Abstract
The undefined poly(3-hydroxybutyrate)- (PHB-) negative mutant R. eutropha PHB-4 was generated in 1970 by 1-nitroso-3-nitro-1-methylguanidine (NMG) treatment. Although being scientific relevant, its genotype remained unknown since its isolation except a recent first investigation. In this study, the mutation causing the PHA-negative phenotype of R. eutropha PHB-4 was confirmed independently: sequence analysis of the phaCAB operon identified a G320A mutation in phaC yielding a stop codon, leading to a massively truncated PhaC protein of 106 amino acids (AS) in R. eutropha PHB-4 instead of 589 AS in the wild type. No other mutations were observed within the phaCAB operon. As further mutations probably occurred in the genome of mutant PHB-4 potentially causing secondary effects on the cells' metabolism, the main focus of the study was to perform a 2D PAGE-based proteome analysis in order to identify differences in the proteomes of the wild type and mutant PHB-4. A total of 20 differentially expressed proteins were identified which provide valuable insights in the metabolomic changes of mutant PHB-4. Besides excretion of pyruvate, mutant PHB-4 encounters the accumulation of intermediates such as pyruvate and acetyl-CoA by enhanced expression of the observed protein species: (i) ThiJ supports biosynthesis of cofactor TPP and thereby reinforces the 2-oxoacid dehydrogenase complexes as PDHC, ADHC and OGDHC in order to convert pyruvate at a higher rate and the (ii) 3-isopropylmalate dehydrogenase LeuB3 apparently directs pyruvate to synthesis of several amino acids. Different (iii) acylCoA-transferases enable transfer reactions between organic acid intermediates, and (iv) citrate lyase CitE4 regenerates oxaloacetate from citrate for conversion with acetyl-CoA in the TCC in an anaplerotic reaction. Substantial amounts of reduction equivalents generated in the TCC are countered by (v) synthesis of more ubiquinones due to enhanced synthesis of MenG2 and MenG3, thereby improving the respiratory chain which accepts electrons from NADH and succinate.
Collapse
Affiliation(s)
- Matthias Raberg
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, Münster, Germany
| | - Birgit Voigt
- Institut für Mikrobiologie, Ernst-Moritz-Arndt Universität, Greifswald, Germany
| | - Michael Hecker
- Institut für Mikrobiologie, Ernst-Moritz-Arndt Universität, Greifswald, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, Münster, Germany
- Department of Environmental Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
- * E-mail:
| |
Collapse
|
25
|
Kim J, Chang JH, Kim KJ. Crystal structure and biochemical properties of the (S)-3-hydroxybutyryl-CoA dehydrogenase PaaH1 from Ralstonia eutropha. Biochem Biophys Res Commun 2014; 448:163-8. [PMID: 24792376 DOI: 10.1016/j.bbrc.2014.04.101] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 04/16/2014] [Indexed: 01/14/2023]
Abstract
3-Hydroxybutyryl-CoA dehydrogenase is an enzyme involved in the synthesis of the biofuel n-butanol by converting acetoacetyl-CoA to 3-hydroxybutyryl-CoA. To investigate the molecular mechanism of n-butanol biosynthesis, we determined crystal structures of the Ralstonia eutropha-derived 3-hydroxybutyryl-CoA dehydrogenase (RePaaH1) in complex with either its cofactor NAD(+) or its substrate acetoacetyl-CoA. While the biologically active structure is dimeric, the monomer of RePaaH1 comprises two separated domains with an N-terminal Rossmann fold and a C-terminal helical bundle for dimerization. In this study, we show that the cofactor-binding site is located on the Rossmann fold and is surrounded by five loops and one helix. The binding mode of the acetoacetyl-CoA substrate was found to be that the adenosine diphosphate moiety is not highly stabilized compared with the remainder of the molecule. Residues involved in catalysis and substrate binding were further confirmed by site-directed mutagenesis experiments, and kinetic properties of RePaaH1were examined as well. Our findings contribute to the understanding of 3-hydroxybutyryl-CoA dehydrogenase catalysis, and will be useful in enhancing the efficiency of n-butanol biosynthesis by structure based protein engineering.
Collapse
Affiliation(s)
- Jieun Kim
- School of Life Sciences, KNU Creative BioResearch Group (BK21 Plus Program), 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
| | - Kyung-Jin Kim
- School of Life Sciences, KNU Creative BioResearch Group (BK21 Plus Program), Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea.
| |
Collapse
|
26
|
Kim EJ, Son HF, Chang JH, Kim KJ. Cloning, expression, purification, crystallization and X-ray crystallographic analysis of β-ketothiolase B from Ralstonia eutropha H16. Acta Crystallogr F Struct Biol Commun 2014; 70:316-9. [PMID: 24598917 PMCID: PMC3944692 DOI: 10.1107/s2053230x14001228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/17/2014] [Indexed: 11/10/2022] Open
Abstract
Polyhydroxyalkanoates are linear polyesters that are produced by bacterial fermentation and are used as biodegradable bioplastics. β-Ketothiolase B (BktB) from Ralstonia eutropha (ReBktB) is a key enzyme for the production of various types of copolymers by catalyzing the condensation reactions of acetyl-CoA with propionyl-CoA and butyryl-CoA. The ReBktB protein was crystallized using the hanging-drop vapour-diffusion method in the presence of 25% polyethylene glycol 3350, 0.1 M bis-tris pH 6.5, 0.2 M lithium sulfate at 295 K. X-ray diffraction data were collected to a maximum resolution of 2.3 Å on a synchrotron beamline. The crystal belonged to space group C2221, with unit-cell parameters a = 106.95, b = 107.24, c = 144.14 Å. With two molecules per asymmetric unit, the crystal volume per unit protein weight (VM) is 2.54 Å(3) Da(-1), which corresponds to a solvent content of approximately 51.5%. The structure was solved by the molecular-replacement method and refinement of the structure is in progress.
Collapse
Affiliation(s)
- 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
| | - Hyeoncheol Francis Son
- 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
| | - 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
| |
Collapse
|
27
|
Proteomic analysis of the purple sulfur bacterium Candidatus “Thiodictyon syntrophicum” strain Cad16T isolated from Lake Cadagno. EUPA OPEN PROTEOMICS 2014. [DOI: 10.1016/j.euprot.2013.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
28
|
Sreedevi S, Unni KN, Sajith S, Priji P, Josh MS, Benjamin S. Bioplastics: Advances in Polyhydroxybutyrate Research. ADVANCES IN POLYMER SCIENCE 2014. [DOI: 10.1007/12_2014_297] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
29
|
Przybylski D, Rohwerder T, Harms H, Yaneva N, Müller RH. Synthesis of the building block 2-hydroxyisobutyrate from fructose and butyrate by Cupriavidus necator H16. Appl Microbiol Biotechnol 2013; 97:8875-85. [PMID: 23942876 DOI: 10.1007/s00253-013-5064-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/11/2013] [Accepted: 06/13/2013] [Indexed: 11/27/2022]
Abstract
2-Hydroxyisobutyryl-coenzyme A mutase, originally discovered in the context of methyl tert-butyl ether degradation in Aquincola tertiaricarbonis L108, catalyzes the isomerization of 3-hydroxybutyryl-coenzyme A (3-HB-CoA) to 2-hydroxyisobutyryl-CoA. It thus constitutes the basis for a biotechnological route from practically any renewable carbon to 2-hydroxyisobutyrate (2-HIB) via the common metabolite 3-hydroxybutyrate. At first sight, recombinant Cupriavidus necator H16 expressing the mutase seems to be well suited for such a synthesis process, as a strong overflow metabolism via (R)-3-HB-CoA is easily induced in this bacterium possessing the poly-3-hydroxybutyrate metabolism. However, the recently established stereospecificity of the mutase, dominantly preferring the (S)-enantiomer of 3-HB-CoA, calls for a closer investigation of C. necator as potential 2-HIB production strain and raised the question about the strain's potential to yield 2-HIB from substrates directly providing (S)-3-HB-CoA. We compared two mutase-expressing C. necator H16 strains for their capability to synthesize 2-HIB from fructose and butyrate, delivering either (R)- or (S)-3-HB-CoA. Our results indicate that due to the enantiospecificity of the mutase, fructose is a weaker substrate for 2-HIB synthesis than butyrate. Production rates achieved with the PHB-negative strain H16 PHB(-)4 on butyrate were higher than on fructose. Using the wild-type did not significantly improve the production rates as the latter showed a 34-fold and a 5-fold lower 2-HIB synthesis rate compared to H16 PHB(-)4 on fructose and butyrate, respectively. Moreover, both strains showed concomitant excretion of undesired side products, such as pyruvate and 3-hydroxybutyrate, significantly decreasing the 2-HIB yield.
Collapse
Affiliation(s)
- Denise Przybylski
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany
| | | | | | | | | |
Collapse
|
30
|
Directed evolution and structural analysis of NADPH-dependent Acetoacetyl Coenzyme A (Acetoacetyl-CoA) reductase from Ralstonia eutropha reveals two mutations responsible for enhanced kinetics. Appl Environ Microbiol 2013; 79:6134-9. [PMID: 23913421 DOI: 10.1128/aem.01768-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
NADPH-dependent acetoacetyl-coenzyme A (acetoacetyl-CoA) reductase (PhaB) is a key enzyme in the synthesis of poly(3-hydroxybutyrate) [P(3HB)], along with β-ketothiolase (PhaA) and polyhydroxyalkanoate synthase (PhaC). In this study, PhaB from Ralstonia eutropha was engineered by means of directed evolution consisting of an error-prone PCR-mediated mutagenesis and a P(3HB) accumulation-based in vivo screening system using Escherichia coli. From approximately 20,000 mutants, we obtained two mutant candidates bearing Gln47Leu (Q47L) and Thr173Ser (T173S) substitutions. The mutants exhibited kcat values that were 2.4-fold and 3.5-fold higher than that of the wild-type enzyme, respectively. In fact, the PhaB mutants did exhibit enhanced activity and P(3HB) accumulation when expressed in recombinant Corynebacterium glutamicum. Comparative three-dimensional structural analysis of wild-type PhaB and highly active PhaB mutants revealed that the beneficial mutations affected the flexibility around the active site, which in turn played an important role in substrate recognition. Furthermore, both the kinetic analysis and crystal structure data supported the conclusion that PhaB forms a ternary complex with NADPH and acetoacetyl-CoA. These results suggest that the mutations affected the interaction with substrates, resulting in the acquirement of enhanced activity.
Collapse
|
31
|
Liu H, Luo Y, Han J, Wu J, Wu Z, Feng D, Cai S, Li M, Liu J, Zhou J, Xiang H. Proteome Reference Map of Haloarcula hispanica and Comparative Proteomic and Transcriptomic Analysis of Polyhydroxyalkanoate Biosynthesis under Genetic and Environmental Perturbations. J Proteome Res 2013; 12:1300-15. [PMID: 23301558 DOI: 10.1021/pr300969m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Hailong Liu
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Yuanming Luo
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Jing Han
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Jinhua Wu
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Zhenfang Wu
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Deqin Feng
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Shuangfeng Cai
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Ming Li
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Jingfang Liu
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Jian Zhou
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| | - Hua Xiang
- State Key
Laboratory of Microbial Resources, Institute
of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China
| |
Collapse
|
32
|
SONG H, ZHANG Y, KONG W, XIA C. Activities of Key Enzymes in the Biosynthesis of Poly-3-Hydroxybutyrate by Methylosinus trichosporium IMV3011. CHINESE JOURNAL OF CATALYSIS 2012. [DOI: 10.1016/s1872-2067(11)60443-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
33
|
Mann MS, Lütke-Eversloh T. Thiolase engineering for enhanced butanol production in Clostridium acetobutylicum. Biotechnol Bioeng 2012; 110:887-97. [PMID: 23096577 DOI: 10.1002/bit.24758] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/01/2012] [Accepted: 10/12/2012] [Indexed: 12/20/2022]
Abstract
Biosynthetic thiolases catalyze the condensation of two molecules acetyl-CoA to acetoacetyl-CoA and represent key enzymes for carbon-carbon bond forming metabolic pathways. An important biotechnological example of such a pathway is the clostridial n-butanol production, comprising various natural constraints that limit titer, yield, and productivity. In this study, the thiolase of Clostridium acetobutylicum, the model organism for solventogenic clostridia, was specifically engineered for reduced sensitivity towards its physiological inhibitor coenzyme A (CoA-SH). A high-throughput screening assay in 96-well microtiter plates was developed employing Escherichia coli as host cells for expression of a mutant thiolase gene library. Screening of this library resulted in the identification of a thiolase derivative with significantly increased activity in the presence of free CoA-SH. This optimized thiolase comprised three amino acid substitutions (R133G, H156N, G222V) and its gene was expressed in C. acetobutylicum ATCC 824 to assess the effect of reduced CoA-SH sensitivity on solvent production. In addition to a clearly delayed ethanol and acetone formation, the ethanol and butanol titers were increased by 46% and 18%, respectively, while the final acetone concentrations were similar to the vector control strain. These results demonstrate that thiolase engineering constitutes a suitable methodology applicable to improve clostridial butanol production, but other biosynthetic pathways involving thiolase-mediated carbon flux limitations might also be subjected to this new metabolic engineering approach.
Collapse
Affiliation(s)
- Miriam S Mann
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Rostock, Germany
| | | |
Collapse
|
34
|
Whole-genome microarray and gene deletion studies reveal regulation of the polyhydroxyalkanoate production cycle by the stringent response in Ralstonia eutropha H16. Appl Environ Microbiol 2012; 78:8033-44. [PMID: 22961894 DOI: 10.1128/aem.01693-12] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Poly(3-hydroxybutyrate) (PHB) production and mobilization in Ralstonia eutropha are well studied, but in only a few instances has PHB production been explored in relation to other cellular processes. We examined the global gene expression of wild-type R. eutropha throughout the PHB cycle: growth on fructose, PHB production using fructose following ammonium depletion, and PHB utilization in the absence of exogenous carbon after ammonium was resupplied. Our results confirm or lend support to previously reported results regarding the expression of PHB-related genes and enzymes. Additionally, genes for many different cellular processes, such as DNA replication, cell division, and translation, are selectively repressed during PHB production. In contrast, the expression levels of genes under the control of the alternative sigma factor σ(54) increase sharply during PHB production and are repressed again during PHB utilization. Global gene regulation during PHB production is strongly reminiscent of the gene expression pattern observed during the stringent response in other species. Furthermore, a ppGpp synthase deletion mutant did not show an accumulation of PHB, and the chemical induction of the stringent response with DL-norvaline caused an increased accumulation of PHB in the presence of ammonium. These results indicate that the stringent response is required for PHB accumulation in R. eutropha, helping to elucidate a thus-far-unknown physiological basis for this process.
Collapse
|
35
|
Machado HB, Dekishima Y, Luo H, Lan EI, Liao JC. A selection platform for carbon chain elongation using the CoA-dependent pathway to produce linear higher alcohols. Metab Eng 2012; 14:504-11. [PMID: 22819734 DOI: 10.1016/j.ymben.2012.07.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 06/01/2012] [Accepted: 07/09/2012] [Indexed: 01/16/2023]
Abstract
Production of green chemicals and fuels using metabolically engineered organisms has been a promising alternative to petroleum-based production. Higher chain alcohols (C4-C8) are of interest because they can be used as chemical feedstock as well as fuels. Recently, the feasibility of n-hexanol synthesis using Escherichia coli has been demonstrated by extending the modified Clostridium CoA-dependent n-butanol synthesis pathway, thereby elongating carbon chain length via reactions in reversed β-oxidation, (or β-reduction). Here, we developed an anaerobic growth selection platform that allows selection or enrichment of enzymes for increased synthesis of C6 and C8 linear alcohols. Using this selection, we were able to improve the carbon flux towards the synthesis of C6 and C8 acyl-CoA intermediates. Replacement of the original enzyme Clostridium acetobutylicum Hbd with Ralstonia eutropha homologue PaaH1 increased production of n-hexanol by 10-fold. Further directed evolution by random mutagenesis of PaaH1 improved n-hexanol and n-octanol production. This anaerobic growth selection platform may be useful for selecting enzymes for production of long-chain alcohols and acids using this CoA-dependent pathway.
Collapse
Affiliation(s)
- Hidevaldo B Machado
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, 5531 Boelter Hall, Los Angeles, California 90095-1570, USA
| | | | | | | | | |
Collapse
|
36
|
Kaddor C, Voigt B, Hecker M, Steinbüchel A. Impact of the Core Components of the Phosphoenolpyruvate-Carbohydrate Phosphotransferase System, HPr and EI, on Differential Protein Expression in Ralstonia eutropha H16. J Proteome Res 2012; 11:3624-36. [DOI: 10.1021/pr300042f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Chlud Kaddor
- Institut für
Molekulare
Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse
3, D-48149 Münster, Germany
| | - Birgit Voigt
- Institut für Mikrobiologie, Ernst-Moritz-Arndt Universität, Friedrich-Ludwig-Jahn-Straße
15, D-17489 Greifswald, Germany
| | - Michael Hecker
- Institut für Mikrobiologie, Ernst-Moritz-Arndt Universität, Friedrich-Ludwig-Jahn-Straße
15, D-17489 Greifswald, Germany
| | - Alexander Steinbüchel
- Institut für
Molekulare
Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse
3, D-48149 Münster, Germany
- King Abdul Aziz University, Jeddah 22254,
Saudi Arabia
| |
Collapse
|
37
|
Brandt U, Raberg M, Voigt B, Hecker M, Steinbüchel A. Elevated poly(3-hydroxybutyrate) synthesis in mutants of Ralstonia eutropha H16 defective in lipopolysaccharide biosynthesis. Appl Microbiol Biotechnol 2012; 95:471-83. [DOI: 10.1007/s00253-012-3909-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 01/11/2012] [Accepted: 01/17/2012] [Indexed: 11/24/2022]
|
38
|
Escapa IF, García JL, Bühler B, Blank LM, Prieto MA. The polyhydroxyalkanoate metabolism controls carbon and energy spillage in Pseudomonas putida. Environ Microbiol 2012; 14:1049-63. [PMID: 22225632 DOI: 10.1111/j.1462-2920.2011.02684.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The synthesis and degradation of polyhydroxyalkanoates (PHAs), the storage polymer of many bacteria, is linked to the operation of central carbon metabolism. To rationalize the impact of PHA accumulation on central carbon metabolism of the prototype bacterium Pseudomonas putida, we have revisited PHA production in quantitative physiology experiments in the wild-type strain vs. a PHA negative mutant growing under low nitrogen conditions. When octanoic acid was used as PHA precursor and as carbon and energy source, we have detected higher intracellular flux via acetyl-CoA in the mutant strain than in the wild type, which correlates with the stimulation of the TCA cycle and glyoxylate shunt observed on the transcriptional level. The mutant defective in carbon and energy storage spills the additional resources, releasing CO(2) instead of generating biomass. Hence, P. putida operates the metabolic network to optimally exploit available resources and channels excess carbon and energy to storage via PHA, without compromising growth. These findings demonstrate that the PHA metabolism plays a critical role in synchronizing global metabolism to availability of resources in PHA-producing microorganisms.
Collapse
Affiliation(s)
- I F Escapa
- Environmental Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain
| | | | | | | | | |
Collapse
|
39
|
Characterization and functional analyses of R-specific enoyl coenzyme A hydratases in polyhydroxyalkanoate-producing Ralstonia eutropha. Appl Environ Microbiol 2011; 78:493-502. [PMID: 22081565 DOI: 10.1128/aem.06937-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A genome survey of polyhydroxyalkanoate (PHA)-producing Ralstonia eutropha H16 detected the presence of 16 orthologs of R-specific enoyl coenzyme A (enoyl-CoA) hydratase, among which three proteins shared high homologies with the enzyme specific to enoyl-CoAs of medium chain length encoded by phaJ4 from Pseudomonas aeruginosa (phaJ4(Pa)). The recombinant forms of the three proteins, termed PhaJ4a(Re) to PhaJ4c(Re), actually showed enoyl-CoA hydratase activity with R specificity, and the catalytic efficiencies were elevated as the substrate chain length increased from C(4) to C(8). PhaJ4a(Re) and PhaJ4b(Re) showed >10-fold-higher catalytic efficiency than PhaJ4c(Re). The functions of the new PhaJ4 proteins were investigated using previously engineered R. eutropha strains as host strains; these strains are capable of synthesizing poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)] from soybean oil. Deletion of phaJ4a(Re) from the chromosome resulted in significant decrease of 3HHx composition in the accumulated copolyester, whereas no change was observed with deletion of phaJ4b(Re) or phaJ4c(Re), indicating that only PhaJ4a(Re) was one of the major enzymes supplying the (R)-3HHx-CoA monomer through β-oxidation. Introduction of phaJ4a(Re) or phaJ4b(Re) into the R. eutropha strains using a broad-host-range vector enhanced the 3HHx composition of the copolyesters, but the introduction of phaJ4c(Re) did not. The two genes were then inserted into the pha operon on chromosome 1 of the engineered R. eutropha by homologous recombination. These modifications enabled the biosynthesis of P(3HB-co-3HHx) composed of a larger 3HHx fraction without a negative impact on cell growth and PHA production on soybean oil, especially when phaJ4a(Re) or phaJ4b(Re) was tandemly introduced with phaJ(Ac) from Aeromonas caviae.
Collapse
|
40
|
Kaddor C, Steinbüchel A. Implications of various phosphoenolpyruvate-carbohydrate phosphotransferase system mutations on glycerol utilization and poly(3-hydroxybutyrate) accumulation in Ralstonia eutropha H16. AMB Express 2011; 1:16. [PMID: 21906371 PMCID: PMC3222305 DOI: 10.1186/2191-0855-1-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 07/13/2011] [Indexed: 11/10/2022] Open
Abstract
The enhanced global biodiesel production is also yielding increased quantities of glycerol as main coproduct. An effective application of glycerol, for example, as low-cost substrate for microbial growth in industrial fermentation processes to specific products will reduce the production costs for biodiesel. Our study focuses on the utilization of glycerol as a cheap carbon source during cultivation of the thermoplastic producing bacterium Ralstonia eutropha H16, and on the investigation of carbohydrate transport proteins involved herein. Seven open reading frames were identified in the genome of strain H16 to encode for putative proteins of the phosphoenolpyruvate-carbohydrate phosphotransferase system (PEP-PTS). Although the core components of PEP-PTS, enzyme I (ptsI) and histidine phosphocarrier protein (ptsH), are available in strain H16, a complete PTS-mediated carbohydrate transport is lacking. Growth experiments employing several PEP-PTS mutants indicate that the putative ptsMHI operon, comprising ptsM (a fructose-specific EIIA component of PTS), ptsH, and ptsI, is responsible for limited cell growth and reduced PHB accumulation (53%, w/w, less PHB than the wild type) of this strain in media containing glycerol as a sole carbon source. Otherwise, the deletion of gene H16_A0384 (ptsN, nitrogen regulatory EIIA component of PTS) seemed to largely compensate the effect of the deleted ptsMHI operon (49%, w/w, PHB). The involvement of the PTS homologous proteins on the utilization of the non-PTS sugar alcohol glycerol and its effect on cell growth as well as PHB and carbon metabolism of R. eutropha will be discussed.
Collapse
|
41
|
Rai R, Yunos DM, Boccaccini AR, Knowles JC, Barker IA, Howdle SM, Tredwell GD, Keshavarz T, Roy I. Poly-3-hydroxyoctanoate P(3HO), a Medium Chain Length Polyhydroxyalkanoate Homopolymer from Pseudomonas mendocina. Biomacromolecules 2011; 12:2126-36. [DOI: 10.1021/bm2001999] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ranjana Rai
- Department of Molecular and Applied Biosciences, School of Life Sciences, University of Westminster, London W1W 6UW, United Kingdom
| | - Darmawati M. Yunos
- Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
| | - Aldo R. Boccaccini
- Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
- Department of Materials Science and Engineering, University of Erlangen−Nuremberg, Cauestr. 6. 91058, Erlangen, Germany
| | - Jonathan C. Knowles
- Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, London WCIX 8LD, United Kingdom
- WCU Research Centre of Nanobiomedical Science, Dankook University, San#29, Anseo-dong, Dongnam-gu, Cheonan-si, Chungnam, 330-714, South Korea
| | - Ian A. Barker
- School of Chemistry, University of Nottingham, NG7 2RD, United Kingdom
| | - Steven M. Howdle
- School of Chemistry, University of Nottingham, NG7 2RD, United Kingdom
| | - Gregory D. Tredwell
- Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
| | - Tajalli Keshavarz
- Department of Molecular and Applied Biosciences, School of Life Sciences, University of Westminster, London W1W 6UW, United Kingdom
| | - Ipsita Roy
- Department of Molecular and Applied Biosciences, School of Life Sciences, University of Westminster, London W1W 6UW, United Kingdom
| |
Collapse
|
42
|
Production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from plant oil by engineered Ralstonia eutropha strains. Appl Environ Microbiol 2011; 77:2847-54. [PMID: 21398488 DOI: 10.1128/aem.02429-10] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The polyhydroxyalkanoate (PHA) copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] has been shown to have potential to serve as a commercial bioplastic. Synthesis of P(HB-co-HHx) from plant oil has been demonstrated with recombinant Ralstonia eutropha strains expressing heterologous PHA synthases capable of incorporating HB and HHx into the polymer. With these strains, however, short-chain-length fatty acids had to be included in the medium to generate PHA with high HHx content. Our group has engineered two R. eutropha strains that accumulate high levels of P(HB-co-HHx) with significant HHx content directly from palm oil, one of the world's most abundant plant oils. The strains express a newly characterized PHA synthase gene from the bacterium Rhodococcus aetherivorans I24. Expression of an enoyl coenzyme A (enoyl-CoA) hydratase gene (phaJ) from Pseudomonas aeruginosa was shown to increase PHA accumulation. Furthermore, varying the activity of acetoacetyl-CoA reductase (encoded by phaB) altered the level of HHx in the polymer. The strains with the highest PHA titers utilized plasmids for recombinant gene expression, so an R. eutropha plasmid stability system was developed. In this system, the essential pyrroline-5-carboxylate reductase gene proC was deleted from strain genomes and expressed from a plasmid, making the plasmid necessary for growth in minimal media. This study resulted in two engineered strains for production of P(HB-co-HHx) from palm oil. In palm oil fermentations, one strain accumulated 71% of its cell dry weight as PHA with 17 mol% HHx, while the other strain accumulated 66% of its cell dry weight as PHA with 30 mol% HHx.
Collapse
|
43
|
Doi Y. Microbial synthesis, physical properties, and biodegradability of polyhydroxyalkanoates. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19950980150] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
44
|
Versatile metabolic adaptations of Ralstonia eutropha H16 to a loss of PdhL, the E3 component of the pyruvate dehydrogenase complex. Appl Environ Microbiol 2011; 77:2254-63. [PMID: 21296938 DOI: 10.1128/aem.02360-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A previous study reported that the Tn5-induced poly(3-hydroxybutyric acid) (PHB)-leaky mutant Ralstonia eutropha H1482 showed a reduced PHB synthesis rate and significantly lower dihydrolipoamide dehydrogenase (DHLDH) activity than the wild-type R. eutropha H16 but similar growth behavior. Insertion of Tn5 was localized in the pdhL gene encoding the DHLDH (E3 component) of the pyruvate dehydrogenase complex (PDHC). Taking advantage of the available genome sequence of R. eutropha H16, observations were verified and further detailed analyses and experiments were done. In silico genome analysis revealed that R. eutropha possesses all five known types of 2-oxoacid multienzyme complexes and five DHLDH-coding genes. Of these DHLDHs, only PdhL harbors an amino-terminal lipoyl domain. Furthermore, insertion of Tn5 in pdhL of mutant H1482 disrupted the carboxy-terminal dimerization domain, thereby causing synthesis of a truncated PdhL lacking this essential region, obviously leading to an inactive enzyme. The defined ΔpdhL deletion mutant of R. eutropha exhibited the same phenotype as the Tn5 mutant H1482; this excludes polar effects as the cause of the phenotype of the Tn5 mutant H1482. However, insertion of Tn5 or deletion of pdhL decreases DHLDH activity, probably negatively affecting PDHC activity, causing the mutant phenotype. Moreover, complementation experiments showed that different plasmid-encoded E3 components of R. eutropha H16 or of other bacteria, like Burkholderia cepacia, were able to restore the wild-type phenotype at least partially. Interestingly, the E3 component of B. cepacia possesses an amino-terminal lipoyl domain, like the wild-type H16. A comparison of the proteomes of the wild-type H16 and of the mutant H1482 revealed striking differences and allowed us to reconstruct at least partially the impressive adaptations of R. eutropha H1482 to the loss of PdhL on the cellular level.
Collapse
|
45
|
Proteomic and transcriptomic elucidation of the mutant ralstonia eutropha G+1 with regard to glucose utilization. Appl Environ Microbiol 2011; 77:2058-70. [PMID: 21278273 DOI: 10.1128/aem.02015-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By taking advantage of the available genome sequence of Ralstonia eutropha H16, glucose uptake in the UV-generated glucose-utilizing mutant R. eutropha G(+)1 was investigated by transcriptomic and proteomic analyses. Data revealed clear evidence that glucose is transported by a usually N-acetylglucosamine-specific phosphotransferase system (PTS)-type transport system, which in this mutant is probably overexpressed due to a derepression of the encoding nag operon by an identified insertion mutation in gene H16_A0310 (nagR). Furthermore, a missense mutation in nagE (membrane component EIICB), which yields a substitution of an alanine by threonine in NagE and may additionally increase glucose uptake, was identified. Phosphorylation of glucose is subsequently mediated by NagF (cytosolic PTS component EIIA-HPr-EI) or glucokinase (GlK), respectively. The inability of the defined deletion mutant R. eutropha G(+)1 ΔnagFEC to utilize glucose strongly confirms this finding. In addition, secondary effects of glucose, which is now intracellularly available as a carbon source, on the metabolism of the mutant cells in the stationary growth phase occurred: intracellular glucose degradation is stimulated by the stronger expression of enzymes involved in the 2-keto-3-deoxygluconate 6-phosphate (KDPG) pathway and in subsequent reactions yielding pyruvate. The intermediate phosphoenolpyruvate (PEP) in turn supports further glucose uptake by the Nag PTS. Pyruvate is then decarboxylated by the pyruvate dehydrogenase multienzyme complex to acetyl coenzyme A (acetyl-CoA), which is directed to poly(3-hydroxybutyrate). The polyester is then synthesized to a greater extent, as also indicated by the upregulation of various enzymes of poly-β-hydroxybutyrate (PHB) metabolism. The larger amounts of NADPH required for PHB synthesis are delivered by significantly increased quantities of proton-translocating NAD(P) transhydrogenases. The current study successfully combined transcriptomic and proteomic investigations to unravel the phenotype of this hitherto-undefined glucose-utilizing mutant.
Collapse
|
46
|
Roles of multiple acetoacetyl coenzyme A reductases in polyhydroxybutyrate biosynthesis in Ralstonia eutropha H16. J Bacteriol 2010; 192:5319-28. [PMID: 20729355 DOI: 10.1128/jb.00207-10] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterium Ralstonia eutropha H16 synthesizes polyhydroxybutyrate (PHB) from acetyl coenzyme A (acetyl-CoA) through reactions catalyzed by a β-ketothiolase (PhaA), an acetoacetyl-CoA reductase (PhaB), and a polyhydroxyalkanoate synthase (PhaC). An operon of three genes encoding these enzymatic steps was discovered in R. eutropha and has been well studied. Sequencing and analysis of the R. eutropha genome revealed putative isologs for each of the PHB biosynthetic genes, many of which had never been characterized. In addition to the previously identified phaB1 gene, the genome contains the isologs phaB2 and phaB3 as well as 15 other potential acetoacetyl-CoA reductases. We have investigated the roles of the three phaB isologs by deleting them from the genome individually and in combination. It was discovered that the gene products of both phaB1 and phaB3 contribute to PHB biosynthesis in fructose minimal medium but that in plant oil minimal medium and rich medium, phaB3 seems to be unexpressed. This raises interesting questions concerning the regulation of phaB3 expression. Deletion of the gene phaB2 did not result in an observable phenotype under the conditions tested, although this gene does encode an active reductase. Addition of the individual reductase genes to the genome of the ΔphaB1 ΔphaB2 ΔphaB3 strain restored PHB production, and in the course of our complementation experiments, we serendipitously created a PHB-hyperproducing mutant. Measurement of the PhaB and PhaA activities of the mutant strains indicated that the thiolase reaction is the limiting step in PHB biosynthesis in R. eutropha H16 during nitrogen-limited growth on fructose.
Collapse
|
47
|
Engineering of pha operon on Cupriavidus necator chromosome for efficient biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from vegetable oil. Polym Degrad Stab 2010. [DOI: 10.1016/j.polymdegradstab.2010.02.026] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
48
|
Yamada M, Matsumoto K, Nakai T, Taguchi S. Microbial production of lactate-enriched poly[(R)-lactate-co-(R)-3-hydroxybutyrate] with novel thermal properties. Biomacromolecules 2010; 10:677-81. [PMID: 19249863 DOI: 10.1021/bm8013846] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Considerable enrichment of the lactate (LA) fraction in Poly[(R)-LA-co-(R)-3-hydroxybutyrate (3HB)] has been achieved, reaching up to 47 mol % from the previous 6 mol % [S. Taguchi et al. Proc. Natl. Acad. Sci. U.S.A. 2008, 105 (45), 17323-17327], when recombinant Escherichia coli W3110, harboring the LA-polymerizing enzyme gene together with three genes for supplying monomers, lactyl-coenzyme A (CoA), and 3-hydroxybutyryl-CoA, were grown on glucose under anaerobic conditions. The molecular weights of the copolymer were M(n) = 1.5 x 10(4) g/mol and M(w) = 2.0 x 10(4) g/mol, respectively. Notably, alkaline-hydrolyzed product analysis revealed that only the (R)-enantiomer of LA was incorporated in the copolymer. Furthermore, the triad sequence of LA-LA-LA was clearly detected in the polymer chain based on NMR analysis. A remarkably contrasting melting temperature was observed between the copolymer obtained here P[(R)-LA-co-(R)-3HB] (157 degrees C) and the chemically synthesized P[(S)-LA-co-(R)-3HB] (105 degrees C) with similar monomer composition.
Collapse
Affiliation(s)
- Miwa Yamada
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, N13-W8, Kita-ku, Sapporo 060-8628, Japan
| | | | | | | |
Collapse
|
49
|
Ryu HW, Hahn SK, Chang YK, Chang HN. Production of poly(3-hydroxybutyrate) by high cell density fed-batch culture of Alcaligenes eutrophus with phospate limitation. Biotechnol Bioeng 2009; 55:28-32. [PMID: 18636441 DOI: 10.1002/(sici)1097-0290(19970705)55:1<28::aid-bit4>3.0.co;2-z] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
High cell density fed-batch fermentation of Alcaligenes eutrophus was carried out for the production of poly(3-hydroxybutyrate) (PHB) in a 60-L fermentor. During the fermentation, pH was controlled with NH(4)OH solution and PHB accumulation was induced by phosphate limitation instead of nitrogen limitation. The glucose feeding was controlled by monitoring dissolved oxygen (DO) concentration and glucose concentration in the culture broth. The glucose concentration fluctuated within the range of 0-20 g/L. We have investigated the effect of initial phosphate concentration on the PHB production when the initial volume was fixed. Using an initial phosphate concentration of 5.5 g/L, the fed-batch fermentation resulted in a final cell concentration of 281 g/L, a PHB concentration of 232 g/L, and a PHB productivity of 3.14 g/L . h, which are the highest values ever reported to date. In this case, PHB content, cell yield from glucose, and PHB yield from glucose were 80, 0.46, and 0.38% (w/w), respectively.
Collapse
Affiliation(s)
- H W Ryu
- BioProcess Engineering Research Center and Department of Chemical Engineering, KAIST, 373-1, Kusong-dong, Yusong-gu, Taejon, 305-701, Korea
| | | | | | | |
Collapse
|
50
|
Abstract
Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates (HAs) synthesized by numerous bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. More than 80 HAs have been detected as constituents of PHAs, which allows these thermoplastic materials to have various mechanical properties resembling hard crystalline polymer or elastic rubber depending on the incorporated monomer units. Even though PHAs have been recognized as good candidates for biodegradable plastics, their high price compared with conventional plastics has limited their use in a wide range of applications. A number of bacteria including Alcaligenes eutrophus, Alcaligenes latus, Azotobacter vinelandii, methylotrophs, pseudomonads, and recombinant Escherichia coli have been employed for the production of PHAs, and the productivity of greater than 2 g PHA/L/h has been achieved. Recent advances in understanding metabolism, molecular biology, and genetics of the PHA-synthesizing bacteria and cloning of more than 20 different PHA biosynthesis genes allowed construction of various recombinant strains that were able to synthesize polyesters having different monomer units and/or to accumulate much more polymers. Also, genetically engineered plants harboring the bacterial PHA biosynthesis genes are being developed for the economical production of PHAs. Improvements in fermentation/separation technology and the development of bacterial strains or plants that more efficiently synthesize PHAs will bring the costs down to make PHAs competitive with the conventional plastics.
Collapse
Affiliation(s)
- S Y Lee
- Department of Chemical Engineering and BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701, Korea. leesy@sorak. kaist.ac. kr
| |
Collapse
|