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Olavarria K, Becker MV, Sousa DZ, van Loosdrecht MC, Wahl SA. Design and thermodynamic analysis of a pathway enabling anaerobic production of poly-3-hydroxybutyrate in Escherichia coli. Synth Syst Biotechnol 2023; 8:629-639. [PMID: 37823039 PMCID: PMC10562921 DOI: 10.1016/j.synbio.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 10/13/2023] Open
Abstract
Utilizing anaerobic metabolisms for the production of biotechnologically relevant products presents potential advantages, such as increased yields and reduced energy dissipation. However, lower energy dissipation may indicate that certain reactions are operating closer to their thermodynamic equilibrium. While stoichiometric analyses and genetic modifications are frequently employed in metabolic engineering, the use of thermodynamic tools to evaluate the feasibility of planned interventions is less documented. In this study, we propose a novel metabolic engineering strategy to achieve an efficient anaerobic production of poly-(R)-3-hydroxybutyrate (PHB) in the model organism Escherichia coli. Our approach involves re-routing of two-thirds of the glycolytic flux through non-oxidative glycolysis and coupling PHB synthesis with NADH re-oxidation. We complemented our stoichiometric analysis with various thermodynamic approaches to assess the feasibility and the bottlenecks in the proposed engineered pathway. According to our calculations, the main thermodynamic bottleneck are the reactions catalyzed by the acetoacetyl-CoA β-ketothiolase (EC 2.3.1.9) and the acetoacetyl-CoA reductase (EC 1.1.1.36). Furthermore, we calculated thermodynamically consistent sets of kinetic parameters to determine the enzyme amounts required for sustaining the conversion fluxes. In the case of the engineered conversion route, the protein pool necessary to sustain the desired fluxes could account for 20% of the whole cell dry weight.
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Affiliation(s)
- Karel Olavarria
- Laboratory of Microbiology, Wageningen University and Research, Stippenenweg 4, 6708 WE, Wageningen, The Netherlands
- Centre for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, Princetonlaan 6, 3584 CB, Utrecht, The Netherlands
| | - Marco V. Becker
- Department of Biotechnology, Applied Sciences Faculty, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Diana Z. Sousa
- Laboratory of Microbiology, Wageningen University and Research, Stippenenweg 4, 6708 WE, Wageningen, The Netherlands
- Centre for Living Technologies, Eindhoven-Wageningen-Utrecht Alliance, Princetonlaan 6, 3584 CB, Utrecht, The Netherlands
| | - Mark C.M. van Loosdrecht
- Department of Biotechnology, Applied Sciences Faculty, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - S. Aljoscha Wahl
- Lehrstuhl für Bioverfahrenstechnik, Friedrich-Alexander-Universität, Paul-Gordan-Strasse 3, 91052, Erlangen, Germany
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2
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Bioreactor scale co-production of poly(hydroxyalkanoate) and rhamnolipids with distinct nitrogen sources. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01014-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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3
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Wang W, Yu X, Wei Y, Ledesma-Amaro R, Ji XJ. Reprogramming the metabolism of Klebsiella pneumoniae for efficient 1,3-propanediol production. Chem Eng Sci 2021. [DOI: 10.1016/j.ces.2021.116539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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4
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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.
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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.
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5
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Liu Y, Low ZJ, Ma X, Liang H, Sinskey AJ, Stephanopoulos G, Zhou K. Using biopolymer bodies for encapsulation of hydrophobic products in bacterium. Metab Eng 2020; 61:206-214. [DOI: 10.1016/j.ymben.2020.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/05/2020] [Accepted: 04/16/2020] [Indexed: 10/24/2022]
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6
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Liu LY, Xie GJ, Xing DF, Liu BF, Ding J, Ren NQ. Biological conversion of methane to polyhydroxyalkanoates: Current advances, challenges, and perspectives. ENVIRONMENTAL SCIENCE AND ECOTECHNOLOGY 2020; 2:100029. [PMID: 36160923 PMCID: PMC9487992 DOI: 10.1016/j.ese.2020.100029] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 05/13/2023]
Abstract
Methane emissions and plastic pollution are critical global challenges. The biological conversion of methane to poly-β-hydroxybutyrate (PHB) not only mitigates methane emissions but also provides biodegradable polymer substitutes for petroleum-based materials used in plastics production. This work provides an early overview of the methane-based PHB advances and discusses challenges and related strategies. Recent advances of PHB, including PHB biosynthetic pathways, methanotrophs, bioreactors, and the performances of PHB materials are introduced. Major challenges of methane-based PHB production are discussed in detail; these include low efficiency of methanotrophs, low gas-liquid mass transfer efficiency, and poor material properties. To overcome these limitations, various approaches are also explored, such as feast-famine regimes, engineered microorganisms, gas-permeable membrane bioreactors, two-phase partitioning bioreactors, poly-β-hydroxybutyrate-co-hydroxyvalerate synthesis, and molecular weight manipulation.
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7
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Gumulya Y, Boxall NJ, Khaleque HN, Santala V, Carlson RP, Kaksonen AH. In a quest for engineering acidophiles for biomining applications: challenges and opportunities. Genes (Basel) 2018; 9:E116. [PMID: 29466321 PMCID: PMC5852612 DOI: 10.3390/genes9020116] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/16/2018] [Accepted: 02/16/2018] [Indexed: 12/27/2022] Open
Abstract
Biomining with acidophilic microorganisms has been used at commercial scale for the extraction of metals from various sulfide ores. With metal demand and energy prices on the rise and the concurrent decline in quality and availability of mineral resources, there is an increasing interest in applying biomining technology, in particular for leaching metals from low grade minerals and wastes. However, bioprocessing is often hampered by the presence of inhibitory compounds that originate from complex ores. Synthetic biology could provide tools to improve the tolerance of biomining microbes to various stress factors that are present in biomining environments, which would ultimately increase bioleaching efficiency. This paper reviews the state-of-the-art tools to genetically modify acidophilic biomining microorganisms and the limitations of these tools. The first part of this review discusses resilience pathways that can be engineered in acidophiles to enhance their robustness and tolerance in harsh environments that prevail in bioleaching. The second part of the paper reviews the efforts that have been carried out towards engineering robust microorganisms and developing metabolic modelling tools. Novel synthetic biology tools have the potential to transform the biomining industry and facilitate the extraction of value from ores and wastes that cannot be processed with existing biomining microorganisms.
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Affiliation(s)
- Yosephine Gumulya
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Floreat WA 6014, Australia.
| | - Naomi J Boxall
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Floreat WA 6014, Australia.
| | - Himel N Khaleque
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Floreat WA 6014, Australia.
| | - Ville Santala
- Laboratory of Chemistry and Bioengineering, Tampere University of Technology (TUT), Tampere, 33101, Finland.
| | - Ross P Carlson
- Department of Chemical and Biological Engineering, Montana State University (MSU), Bozeman, MT 59717, USA.
| | - Anna H Kaksonen
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Floreat WA 6014, Australia.
- School of Pathology and Laboratory Medicine, University of Western Australia, Crawley, WA 6009, Australia.
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8
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Ouyang P, Wang H, Hajnal I, Wu Q, Guo Y, Chen GQ. Increasing oxygen availability for improving poly(3-hydroxybutyrate) production by Halomonas. Metab Eng 2018; 45:20-31. [DOI: 10.1016/j.ymben.2017.11.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/09/2017] [Accepted: 11/12/2017] [Indexed: 01/01/2023]
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9
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Chen GQ, Jiang XR. Engineering microorganisms for improving polyhydroxyalkanoate biosynthesis. Curr Opin Biotechnol 2017; 53:20-25. [PMID: 29169056 DOI: 10.1016/j.copbio.2017.10.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/27/2017] [Accepted: 10/30/2017] [Indexed: 01/22/2023]
Abstract
Biosynthesis of polyhydroxyalkanoates (PHA) has been studied since the 1920s. The biosynthesis pathways have been well understood and various attempts have been made to improve the PHA biosynthesis efficiency. Recent progresses have been focused on systematic improvements on PHA biosynthesis including changing growth pattern for rapid proliferation, engineering to enlarge cell sizes for more PHA accumulation space, reprogramming the PHA synthesis pathways using optimized RBS and promoter, redirecting metabolic flux to PHA synthesis using CRISPR/Cas9 tools, and very importantly, the employment of non-traditional host such as halophiles for reduced complexity on PHA production. All of the efforts should lead to ultrahigh PHA accumulation, controllable PHA compositions and molecular weights, open and continuous PHA production with gravity separation processes, resulting in competitive PHA production cost.
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Affiliation(s)
- Guo-Qiang Chen
- MOE Lab of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China; Manchester Institute of Biotechnology, Centre for Synthetic Biology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK.
| | - Xiao-Ran Jiang
- MOE Lab of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
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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.
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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.
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11
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Covalent-display of an active chimeric-recombinant tissue plasminogen activator on polyhydroxybutyrate granules surface. Biotechnol Lett 2017; 39:1683-1688. [DOI: 10.1007/s10529-017-2416-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/20/2017] [Indexed: 10/19/2022]
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12
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Velasco Alvarez MI, Ten Pierick A, van Dam PTN, Maleki Seifar R, van Loosdrecht MCM, Wahl SA. Microscale Quantitative Analysis of Polyhydroxybutyrate in Prokaryotes Using IDMS. Metabolites 2017; 7:metabo7020019. [PMID: 28513556 PMCID: PMC5487990 DOI: 10.3390/metabo7020019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/13/2017] [Accepted: 05/15/2017] [Indexed: 12/02/2022] Open
Abstract
Poly(3-hydroxybutyrate) (PHB) is an interesting biopolymer for replacing petroleum-based plastics, its biological production is performed in natural and engineered microorganisms. Current metabolic engineering approaches rely on high-throughput strain construction and screening. Analytical procedures have to be compatible with the small scale and speed of these approaches. Here, we present a method based on isotope dilution mass spectrometry (IDMS) and propanolysis extraction of poly(3-hydroxybutyrate) from an Escherichia coli strain engineered for PHB production. As internal standard (IS), we applied an uniformly labeled 13C-cell suspension, of an E. coli PHB producing strain, grown on U-13C-glucose as C-source. This internal 13C-PHB standard enables to quantify low concentrations of PHB (LOD of 0.01 µg/gCDW) from several micrograms of biomass. With this method, a technical reproducibility of about 1.8% relative standard deviation is achieved. Furthermore, the internal standard is robust towards different sample backgrounds and dilutions. The early addition of the internal standard also enables higher reproducibility and increases sensitivity and throughput by simplified sample preparation steps.
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Affiliation(s)
- Mariana Itzel Velasco Alvarez
- Cell Systems Engineering Group, Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands.
| | - Angela Ten Pierick
- BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands.
| | - Patricia T N van Dam
- Cell Systems Engineering Group, Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands.
| | - Reza Maleki Seifar
- Cell Systems Engineering Group, Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands.
| | - Mark C M van Loosdrecht
- Cell Systems Engineering Group, Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands.
| | - S Aljoscha Wahl
- Cell Systems Engineering Group, Department of Biotechnology, Delft University of Technology, 2629 HZ Delft, The Netherlands.
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Moreira JB, Terra ALM, Costa JAV, Morais MG. UTILIZATION OF CO2 IN SEMI-CONTINUOUS CULTIVATION OF Spirulina sp. AND Chlorella fusca AND EVALUATION OF BIOMASS COMPOSITION. BRAZILIAN JOURNAL OF CHEMICAL ENGINEERING 2016. [DOI: 10.1590/0104-6632.20160333s20150135] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Carlson RP, Oshota O, Shipman M, Caserta JA, Hu P, Saunders CW, Xu J, Jay ZJ, Reeder N, Richards A, Pettigrew C, Peyton BM. Integrated molecular, physiological and in silico characterization of two Halomonas isolates from industrial brine. Extremophiles 2016; 20:261-74. [PMID: 26888357 DOI: 10.1007/s00792-015-0806-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 12/06/2015] [Indexed: 01/15/2023]
Abstract
Two haloalkaliphilic bacteria isolated from industrial brine solutions were characterized via molecular, physiological, and in silico metabolic pathway analyses. Genomes from the organisms, designated Halomonas BC1 and BC2, were sequenced; 16S ribosomal subunit-based phylogenetic analysis revealed a high level of similarity to each other and to Halomonas meridiana. Both strains were moderate halophiles with near optimal specific growth rates (≥60 % μ max) observed over <0.1-5 % (w/v) NaCl and pH ranging from 7.4 to 10.2. Isolate BC1 was further characterized by measuring uptake or synthesis of compatible solutes under different growth conditions; in complex medium, uptake and accumulation of external glycine betaine was observed while ectoine was synthesized de novo in salts medium. Transcriptome analysis of isolate BC1 grown on glucose or citrate medium measured differences in glycolysis- and gluconeogenesis-based metabolisms, respectively. The annotated BC1 genome was used to build an in silico, genome-scale stoichiometric metabolic model to study catabolic energy strategies and compatible solute synthesis under gradients of oxygen and nutrient availability. The theoretical analysis identified energy metabolism challenges associated with acclimation to high salinity and high pH. The study documents central metabolism data for the industrially and scientifically important haloalkaliphile genus Halomonas.
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Affiliation(s)
- Ross P Carlson
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA. .,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.
| | - Olusegun Oshota
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Matt Shipman
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,U.S. Navy, Washington, DC, USA
| | | | - Ping Hu
- Procter and Gamble Co., Cincinnati, OH, 45202, USA
| | | | - Jun Xu
- Procter and Gamble Co., Cincinnati, OH, 45202, USA
| | - Zackary J Jay
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA
| | - Nancy Reeder
- Procter and Gamble Co., Cincinnati, OH, 45202, USA
| | - Abigail Richards
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA
| | | | - Brent M Peyton
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA. .,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.
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15
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The CreC Regulator of Escherichia coli, a New Target for Metabolic Manipulations. Appl Environ Microbiol 2015; 82:244-54. [PMID: 26497466 DOI: 10.1128/aem.02984-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 10/15/2015] [Indexed: 11/20/2022] Open
Abstract
The CreBC (carbon source-responsive) two-component regulation system of Escherichia coli affects a number of functions, including intermediary carbon catabolism. The impacts of different creC mutations (a ΔcreC mutant and a mutant carrying the constitutive creC510 allele) on bacterial physiology were analyzed in glucose cultures under three oxygen availability conditions. Differences in the amounts of extracellular metabolites produced were observed in the null mutant compared to the wild-type strain and the mutant carrying creC510 and shown to be affected by oxygen availability. The ΔcreC strain secreted more formate, succinate, and acetate but less lactate under low aeration. These metabolic changes were associated with differences in AckA and LdhA activities, both of which were affected by CreC. Measurement of the NAD(P)H/NAD(P)(+) ratios showed that the creC510 strain had a more reduced intracellular redox state, while the opposite was observed for the ΔcreC mutant, particularly under intermediate oxygen availability conditions, indicating that CreC affects redox balance. The null mutant formed more succinate than the wild-type strain under both low aeration and no aeration. Overexpression of the genes encoding phosphoenolpyruvate carboxylase from E. coli and a NADH-forming formate dehydrogenase from Candida boidinii in the ΔcreC mutant further increased the yield of succinate on glucose. Interestingly, the elimination of ackA and adhE did not significantly improve the production of succinate. The diverse metabolic effects of this regulator on the central biochemical network of E. coli make it a good candidate for metabolic-engineering manipulations to enhance the formation of bioproducts, such as succinate.
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16
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Horvat P, Koller M, Braunegg G. Recent advances in elementary flux modes and yield space analysis as useful tools in metabolic network studies. World J Microbiol Biotechnol 2015; 31:1315-28. [DOI: 10.1007/s11274-015-1887-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 06/05/2015] [Indexed: 11/25/2022]
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17
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Sekar K, Tyo KE. Regulatory effects on central carbon metabolism from poly-3-hydroxybutryate synthesis. Metab Eng 2015; 28:180-189. [DOI: 10.1016/j.ymben.2015.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 12/29/2014] [Accepted: 01/05/2015] [Indexed: 10/24/2022]
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18
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Effects of cascaded vgb promoters on poly(hydroxybutyrate) (PHB) synthesis by recombinant Escherichia coli grown micro-aerobically. Appl Microbiol Biotechnol 2014; 98:10013-21. [DOI: 10.1007/s00253-014-6059-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 08/23/2014] [Accepted: 08/28/2014] [Indexed: 01/29/2023]
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19
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Tamis J, Marang L, Jiang Y, van Loosdrecht MC, Kleerebezem R. Modeling PHA-producing microbial enrichment cultures—towards a generalized model with predictive power. N Biotechnol 2014; 31:324-34. [DOI: 10.1016/j.nbt.2013.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 10/25/2013] [Accepted: 11/25/2013] [Indexed: 10/25/2022]
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Adaptation of Escherichia coli to elevated sodium concentrations increases cation tolerance and enables greater lactic acid production. Appl Environ Microbiol 2014; 80:2880-8. [PMID: 24584246 DOI: 10.1128/aem.03804-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Adaptive evolution was employed to generate sodium (Na(+))-tolerant mutants of Escherichia coli MG1655. Four mutants with elevated sodium tolerance, designated ALS1184, ALS1185, ALS1186, and ALS1187, were independently isolated after 73 days of serial transfer in medium containing progressively greater Na(+) concentrations. The isolates also showed increased tolerance of K(+), although this cation was not used for selective pressure. None of the adapted mutants showed increased tolerance to the nonionic osmolyte sucrose. Several physiological parameters of E. coli MG1655 and ALS1187, the isolate with the greatest Na(+) tolerance, were calculated and compared using glucose-limited chemostats. Genome sequencing showed that the ALS1187 isolate contained mutations in five genes, emrR, hfq, kil, rpsG, and sspA, all of which could potentially affect the ability of E. coli to tolerate Na(+). Two of these genes, hfq and sspA, are known to be involved in global regulatory processes that help cells endure a variety of cellular stresses. Pyruvate formate lyase knockouts were constructed in strains MG1655 and ALS1187 to determine whether increased Na(+) tolerance afforded increased anaerobic generation of lactate. In fed-batch fermentations, E. coli ALS1187 pflB generated 76.2 g/liter lactate compared to MG1655 pflB, which generated only 56.3 g/liter lactate.
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Enhanced co-production of hydrogen and poly-(R)-3-hydroxybutyrate by recombinant PHB producing E. coli over-expressing hydrogenase 3 and acetyl-CoA synthetase. Metab Eng 2012; 14:496-503. [DOI: 10.1016/j.ymben.2012.07.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/29/2012] [Accepted: 07/19/2012] [Indexed: 11/24/2022]
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Carlson RP, Oshota OJ, Taffs RL. Systems analysis of microbial adaptations to simultaneous stresses. Subcell Biochem 2012; 64:139-57. [PMID: 23080249 DOI: 10.1007/978-94-007-5055-5_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Microbes live in multi-factorial environments and have evolved under a variety of concurrent stresses including resource scarcity. Their metabolic organization is a reflection of their evolutionary histories and, in spite of decades of research, there is still a need for improved theoretical tools to explain fundamental aspects of microbial physiology. Using ecological and economic concepts, this chapter explores a resource-ratio based theory to elucidate microbial strategies for extracting and channeling mass and energy. The theory assumes cellular fitness is maximized by allocating scarce resources in appropriate proportions to multiple stress responses. Presented case studies deconstruct metabolic networks into a complete set of minimal biochemical pathways known as elementary flux modes. An economic analysis of the elementary flux modes tabulates enzyme atomic synthesis requirements from amino acid sequences and pathway operating costs from catabolic efficiencies, permitting characterization of inherent tradeoffs between resource investment and phenotype. A set of elementary flux modes with competitive tradeoffs properties can be mathematically projected onto experimental fluxomics datasets to decompose measured phenotypes into metabolic adaptations, interpreted as cellular responses proportional to the experienced culturing stresses. The resource-ratio based method describes the experimental phenotypes with greater accuracy than other contemporary approaches and further analysis suggests the results are both statistically and biologically significant. The insight into metabolic network design principles including tradeoffs associated with concurrent stress adaptation provides a foundation for interpreting physiology as well as for rational control and engineering of medically, environmentally, and industrially relevant microbes.
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Affiliation(s)
- Ross P Carlson
- Chemical and Biological Engineering Department, Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717-3920, USA,
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23
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Lactate fraction dependent mechanical properties of semitransparent poly(lactate-co-3-hydroxybutyrate)s produced by control of lactyl-CoA monomer fluxes in recombinant Escherichia coli. J Biotechnol 2011; 154:255-60. [PMID: 21640144 DOI: 10.1016/j.jbiotec.2011.05.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 05/11/2011] [Accepted: 05/19/2011] [Indexed: 11/22/2022]
Abstract
In order to evaluate the mechanical properties of poly(lactate-co-3-hydroxybutyrate) [P(LA-co-3HB)] and its correlation with the LA fraction, P(LA-co-3HB)s with a variety of LA fractions were prepared using recombinant Escherichia coli expressing the LA-polymerizing enzyme and monomer supplying enzymes. The LA-overproducing mutant E. coli JW0885 with a pflA gene disruption was used for the LA-enriched polymer production. The LA fraction was also varied by jar-fermentor based fine-regulation of the anaerobic status of the culture conditions, resulting in LA fractions ranging from 4 to 47 mol%. In contrary to the opaque P(3HB) film, the copolymer films attained semitransparency depending on the LA fraction. Young's modulus values of the P(LA-co-3HB)s (from 148 to 905 MPa) were lower than those of poly(lactic acid) (PLA) (1020 MPa) and P(3HB) (1079 MPa). In addition, the value of elongation at break of the copolymer with 29 mol% LA reached 150%. In conclusion, P(LA-co-3HB)s were found to be a comparatively pliable and flexible material, differing from both of the rigid homopolymers.
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Jian J, Zhang SQ, Shi ZY, Wang W, Chen GQ, Wu Q. Production of polyhydroxyalkanoates by Escherichia coli mutants with defected mixed acid fermentation pathways. Appl Microbiol Biotechnol 2010; 87:2247-56. [PMID: 20535465 DOI: 10.1007/s00253-010-2706-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 05/27/2010] [Accepted: 05/28/2010] [Indexed: 10/19/2022]
Abstract
A series of Escherichia coli BW25113 mutants with reduced mixed acid fermentation were constructed. Genes ackA-pta, poxB, ldhA, adhE, and pflB encoding acetate kinase, phosphate acetyltransferase, pyruvate oxidase, D: -lactate dehydrogenase, acetaldehyde dehydrogenase, and pyruvate formate-lyase, respectively, were deleted successively. When grown under microaerobic condition, the mutants reduced approximately 90% acetate excretion after the deletion of genes ackA-pta and poxB. Production of lactate, ethanol, and formate was also significantly reduced after the deletion of genes ldhA, adhE, and pflB, respectively. The accumulation of biomass and poly(3-hydroxybutyrate) (PHB) were significantly enhanced after deleting the mixed acid fermentation. E. coli mutant BWapld with deletions of ackA-pta, poxB, ldhA, and adhE produced twice the cell dry weight (CDW) and 3.5 times of PHB compared with its wild-type under microaerobic conditions. E. coli mutant BWapl with deletions of ackA-pta, poxB, and ldhA also achieved nearly twice CDW and three times of PHB content in comparison to the wild-type during 48 h static cultivation. Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was observed in the mutants under static cultivation. E. coli mutant BWapld could produce approximately 50 wt.% P(3HB-co-3HV) consisting of 5 mol% of 3-hydroxyvalerate (3HV) under aerobic conditions, when the seed culture was inoculated at an appropriate time. When ackA-pta, poxB, ldhA, adhE, and pflB were deleted, E. coli mutant BWapldf accumulated over 70 wt.% P(3HB-co-3HV) consisting of 8 mol% 3HV under aerobic conditions.
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Affiliation(s)
- Jia Jian
- Department of Biology, Tsinghua University, Beijing, China
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25
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Faust K, Croes D, van Helden J. In response to 'Can sugars be produced from fatty acids? A test case for pathway analysis tools'. ACTA ACUST UNITED AC 2009; 25:3202-5. [PMID: 19776213 DOI: 10.1093/bioinformatics/btp557] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
MOTIVATION In their article entitled 'Can sugars be produced from fatty acids? A test case for pathway analysis tools' de Figueiredo and co-authors assess the performance of three pathway prediction tools (METATOOL, PathFinding and Pathway Hunter Tool) using the synthesis of glucose-6-phosphate (G6P) from acetyl-CoA in humans as a test case. We think that this article is biased for three reasons: (i) the metabolic networks used as input for the respective tools were of very different sizes; (ii) the 'assessment' is restricted to two study cases; (iii) developers are inherently more skilled to use their own tools than those developed by other people. We extended the analyses led by de Figueiredo and clearly show that the apparent superior performance of their tool (METATOOL) is partly due to the differences in input network sizes. We also see a conceptual problem in the comparison of tools that serve different purposes. In our opinion, metabolic path finding and elementary mode analysis are answering different biological questions, and should be considered as complementary rather than competitive approaches. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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26
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Chen GQ. A microbial polyhydroxyalkanoates (PHA) based bio- and materials industry. Chem Soc Rev 2009; 38:2434-46. [PMID: 19623359 DOI: 10.1039/b812677c] [Citation(s) in RCA: 723] [Impact Index Per Article: 48.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Biopolyesters polyhydroxyalkanoates (PHA) produced by many bacteria have been investigated by microbiologists, molecular biologists, biochemists, chemical engineers, chemists, polymer experts and medical researchers. PHA applications as bioplastics, fine chemicals, implant biomaterials, medicines and biofuels have been developed and are covered in this critical review. Companies have been established or involved in PHA related R&D as well as large scale production. Recently, bacterial PHA synthesis has been found to be useful for improving robustness of industrial microorganisms and regulating bacterial metabolism, leading to yield improvement on some fermentation products. In addition, amphiphilic proteins related to PHA synthesis including PhaP, PhaZ or PhaC have been found to be useful for achieving protein purification and even specific drug targeting. It has become clear that PHA and its related technologies are forming an industrial value chain ranging from fermentation, materials, energy to medical fields (142 references).
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Affiliation(s)
- Guo-Qiang Chen
- Dept Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China.
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27
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Wei XX, Shi ZY, Yuan MQ, Chen GQ. Effect of anaerobic promoters on the microaerobic production of polyhydroxybutyrate (PHB) in recombinant Escherichia coli. Appl Microbiol Biotechnol 2009; 82:703-12. [DOI: 10.1007/s00253-008-1816-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 12/05/2008] [Accepted: 12/07/2008] [Indexed: 11/30/2022]
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Gilbert A, Srienc F. Optimized evolution in the cytostat: a Monte Carlo simulation. Biotechnol Bioeng 2008; 102:221-31. [PMID: 18781685 DOI: 10.1002/bit.22045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Rational genetic alterations of a microorganism for a specific purpose are not possible in many situations where our knowledge of the relationship between phenotype and genotype is limited. In such cases evolutionary techniques must be applied. Evolutionary methods are usually time consuming; therefore, more efficient techniques are highly desirable. In this work we present the optimization of strain development in a cytostat. The time required for mutant strain isolation is dependent on the total cells present, the wild-type specific growth rate, the beneficial mutation probability, the mutant specific growth rate, and several bioreactor operating conditions. These parameters are highly related, and a theoretical model, as developed here, is needed to define the conditions that optimize the isolation. The model is based on a discrete, stochastic description of mutant formation and selection in the background of abundant wild-type cells. Using the model, we determined the optimal cytostat operating strategy for mutant isolation that varies according to the probability of beneficial mutations. It is also shown that mutants with as little as a 5% growth advantage can be isolated in less than 15 days which is significantly faster than in a chemostat. The described optimal mutant isolation procedure is expected to be particularly useful for the generation of industrial strains that are robust in challenging growth conditions.
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Affiliation(s)
- Alan Gilbert
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
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Trinh CT, Wlaschin A, Srienc F. Elementary mode analysis: a useful metabolic pathway analysis tool for characterizing cellular metabolism. Appl Microbiol Biotechnol 2008; 81:813-26. [PMID: 19015845 DOI: 10.1007/s00253-008-1770-1] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2008] [Revised: 10/23/2008] [Accepted: 10/25/2008] [Indexed: 12/19/2022]
Abstract
Elementary mode analysis is a useful metabolic pathway analysis tool to identify the structure of a metabolic network that links the cellular phenotype to the corresponding genotype. The analysis can decompose the intricate metabolic network comprised of highly interconnected reactions into uniquely organized pathways. These pathways consisting of a minimal set of enzymes that can support steady state operation of cellular metabolism represent independent cellular physiological states. Such pathway definition provides a rigorous basis to systematically characterize cellular phenotypes, metabolic network regulation, robustness, and fragility that facilitate understanding of cell physiology and implementation of metabolic engineering strategies. This mini-review aims to overview the development and application of elementary mode analysis as a metabolic pathway analysis tool in studying cell physiology and as a basis of metabolic engineering.
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Affiliation(s)
- Cong T Trinh
- Department of Chemical Engineering and Materials Science, University of Minnesota, 151 Amundson Hall, 421 Washington Ave SE, Minneapolis, MN 55455, USA
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30
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Ugwu C, Tokiwa Y, Aoyagi H, Uchiyama H, Tanaka H. UV mutagenesis ofCupriavidus necatorfor extracellular production of (R)-3-hydroxybutyric acid. J Appl Microbiol 2008; 105:236-42. [DOI: 10.1111/j.1365-2672.2008.03774.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Pettinari MJ, Nikel PI, Ruiz JA, Méndez BS. ArcA redox mutants as a source of reduced bioproducts. J Mol Microbiol Biotechnol 2008; 15:41-7. [PMID: 18349549 DOI: 10.1159/000111991] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Escherichia coli and other facultative anaerobes can adapt their metabolism according to oxygen availability by means of aerobic and anaerobic respiration and fermentation. ArcAB is a two-component signal transduction system that controls, at the transcriptional level, the choice of energy generation pathway according to the intracellular redox state. High throughput studies on different redox regulator mutants, involving transcriptome analysis, RT-PCR and phenotypic arrays enabled the elucidation of a repertoire of operons coordinated by ArcA which extended beyond respiration control including, among others, those which code for survival, chromosome replication and degradation of fatty acids. Flux analysis by (13)C labeling provided new clues to the understanding of the distribution of metabolites mediated by ArcAB. The genetic manipulation of this regulator proved to be useful for the generation of reduced products of commercial value.
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Affiliation(s)
- M Julia Pettinari
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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Poly(3-hydroxybutyrate) synthesis from glycerol by a recombinant Escherichia coli arcA mutant in fed-batch microaerobic cultures. Appl Microbiol Biotechnol 2007; 77:1337-43. [PMID: 18034236 DOI: 10.1007/s00253-007-1255-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 10/22/2007] [Accepted: 10/23/2007] [Indexed: 10/22/2022]
Abstract
Poly(3-hydroxybutyrate) (PHB) synthesis was analyzed under microaerobic conditions in a recombinant Escherichia coli arcA mutant using glycerol as the main carbon source. The effect of several additives was assessed in a semi-synthetic medium by the 'one-factor-at-a-time' technique. Casein amino acids (CAS) concentration was an important factor influencing both growth and PHB accumulation. Three factors exerting a statistically significant influence on PHB synthesis were selected by using a Plackett-Burman screening design [glycerol, CAS, and initial cell dry weight (CDW) concentrations] and then optimized through a Box-Wilson design. Under such optimized conditions (22.02 g l(-1) glycerol, 1.78 g l(-1) CAS, and 1.83 g l(-1) inoculum) microaerobic batch cultures gave rise to 8.37 g l(-1) CDW and 3.52 g l(-1) PHB in 48 h (PHB content of 42%) in a benchtop bioreactor. Further improvements in microaerobic PHB accumulation were obtained in fed-batch cultures, in which glycerol was added to maintain its concentration above 5 g l(-1). After 60 h, CDW and PHB concentration reached 21.17 and 10.81 g l(-1), respectively, which results in a PHB content of 51%. Microaerobic fed-batch cultures allowed a 2.57-fold increase in volumetric productivity when compared with batch cultures.
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33
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Carlson R, Srienc F. Effects of recombinant precursor pathway variations on poly[(R)-3-hydroxybutyrate] synthesis in Saccharomyces cerevisiae. J Biotechnol 2006; 124:561-73. [PMID: 16530287 DOI: 10.1016/j.jbiotec.2006.01.035] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 01/05/2006] [Accepted: 01/16/2006] [Indexed: 11/26/2022]
Abstract
Different recombinant R-3-hydroxybutyryl-CoA (3-HB) synthesis pathways strongly influenced the rate and accumulation of the biopolymer poly[(R)-3-hydroxybutyrate] (PHB) in Saccharomyces cerevisiae. It has been previously shown that expression of the Cupriavidus necator PHB synthase gene leads to PHB accumulation in S. cerevisiae [Leaf, T., Peterson, M., Stoup, S., Somers, D., Srienc, F., 1996. Saccharomyces cerevisiae expressing bacterial polyhydroxybutyrate synthase produces poly-3-hydroxybutyrate. Microbiology 142, 1169-1180]. This finding indicates that native S. cerevisiae expresses genes capable of synthesizing the correct stereochemical substrate for the synthase enzyme. The effects of variations of 3-HB precursor pathways on PHB accumulation were investigated by expressing combinations of C. necator PHB pathway genes. When only the PHB synthase gene was expressed, the cells accumulated biopolymer to approximately 0.2% of their cell dry weight. When the PHB synthase and reductase gene were co-expressed, the PHB levels increased approximately 18 fold to about 3.5% of the cell dry weight. When the beta-ketothiolase, reductase and synthase genes were all expressed, the strain accumulated PHB to approximately 9% of the cell dry weight which is 45 fold higher than in the strain with only the synthase gene. Fluorescent microscopic analysis revealed significant cell-to-cell heterogeneity in biopolymer accumulation. While the population average for the strain expressing three PHB genes was approximately 9% of the cell dry weight, some cells accumulated PHB in excess of 50% of their cell volume. Other cells accumulated no biopolymer. In addition, the recombinant strain was shown to co-produce ethanol and PHB under anaerobic conditions. These results demonstrate that the technologically important organism S. cerevisiae is capable of accumulating PHB aerobically and anaerobically at levels similar to some bacterial systems. The easily assayed PHB system also creates a convenient means of probing in vivo the presence of intracellular metabolites which could be useful for studying the intermediary metabolism of S. cerevisiae.
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Affiliation(s)
- Ross Carlson
- Department of Chemical Engineering and Materials Science, and BioTechnology Institute, University of Minnesota, Minneapolis/St. Paul, MN 55108, USA
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Wlaschin AP, Trinh CT, Carlson R, Srienc F. The fractional contributions of elementary modes to the metabolism of Escherichia coli and their estimation from reaction entropies. Metab Eng 2006; 8:338-52. [PMID: 16581276 DOI: 10.1016/j.ymben.2006.01.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 01/04/2006] [Accepted: 01/31/2006] [Indexed: 11/21/2022]
Abstract
The metabolism of a cell can be viewed as a weighted sum of elementary modes. Due to the multiplicity of modes the identification of the individual weights represents a non-trivial problem. To enable the determination of weighting factors we have identified and implemented two gene deletions in combination with defined growth conditions that limit the metabolism from 4374 original elementary modes to 24 elementary modes for a non-PHB synthesizing control and 40 modes for a PHB synthesizing strain. These remaining modes can be further grouped into five families that have the same overall stoichiometry. Thus, the complexity of the problem is significantly reduced, and weighting factors for each family of modes could be determined from the measurement of accumulation rates of metabolites. Moreover, it is shown that individual weights are inversely correlated with the entropy generated by the operation of the used pathways defined in elementary modes. This suggests that evolution developed cellular regulatory patterns that permit diversity of pathways while favoring efficient pathways with low entropy generation. Furthermore, such correlation provides a rational way of estimating metabolic fluxes based on the thermodynamic properties of elementary modes. This is demonstrated with an example in which experimentally determined, intracellular fluxes are shown to be highly correlated with fluxes computed based on elementary modes and reaction entropies. The analysis suggests that the set of elementary modes can be interpreted analogous to a metabolic ensemble of quantum states of a macroscopic system.
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Affiliation(s)
- Aaron P Wlaschin
- 240 Gortner Laboratory, Department of Chemical Engineering and Materials Science, and BioTechnology Institute, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN 55455/55108, USA
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35
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Wang X, Xu P, Yuan Y, Liu C, Zhang D, Yang Z, Yang C, Ma C. Modeling for gellan gum production by Sphingomonas paucimobilis ATCC 31461 in a simplified medium. Appl Environ Microbiol 2006; 72:3367-74. [PMID: 16672479 PMCID: PMC1472386 DOI: 10.1128/aem.72.5.3367-3374.2006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Accepted: 03/02/2006] [Indexed: 11/20/2022] Open
Abstract
Gellan gum production was carried out by Sphingomonas paucimobilis ATCC 31461 in a simplified medium with a short incubation time, and a kinetic model for understanding, controlling, and optimizing the fermentation process was proposed. The results revealed that glucose was the best carbon source and that the optimal concentration was 30 g liter(-1). As for the fermenting parameters, considerably large amounts of gellan gum were yielded by an 8-h-old culture and a 4% inoculum at 200 rpm on a rotary shaker. Under the optimized conditions, the maximum level of gellan gum (14.75 g liter(-1)) and the highest conversion efficiency (49.17%) were obtained in a 30-liter fermentor in batch fermentation. Logistic and Luedeking-Piret models were confirmed to provide a good description of gellan gum fermentation, which gave some support for the study of gellan gum fermentation kinetics. Additionally, this study is the first demonstration that gellan gum production is largely growth associated by analysis of kinetics in its batch fermentation process. Based on model prediction, higher gellan gum production (17.71 g liter(-1)) and higher conversion efficiency (57.12%) were obtained in fed-batch fermentation at the same total glucose concentration (30 g liter(-1)).
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Affiliation(s)
- Xia Wang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, People's Republic of China
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36
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Nikel PI, Pettinari MJ, Galvagno MA, Méndez BS. Poly(3-hydroxybutyrate) synthesis by recombinant Escherichia coli arcA mutants in microaerobiosis. Appl Environ Microbiol 2006; 72:2614-20. [PMID: 16597965 PMCID: PMC1448993 DOI: 10.1128/aem.72.4.2614-2620.2006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 02/02/2006] [Indexed: 11/20/2022] Open
Abstract
We assessed the effects of different arcA mutations on poly(3-hydroxybutyrate) (PHB) synthesis in recombinant Escherichia coli strains carrying the pha synthesis genes from Azotobacter sp. strain FA8. The arcA mutations used were an internal deletion and the arcA2 allele, a leaky mutation for some of the characteristics of the Arc phenotype which confers high respiratory capacity. PHB synthesis was not detected in the wild-type strain in shaken flask cultures under low-oxygen conditions, while ArcA mutants gave rise to polymer accumulation of up to 24% of their cell dry weight. When grown under microaerobic conditions in a bioreactor, the arcA deletion mutant reached a PHB content of 27% +/- 2%. Under the same conditions, higher biomass and PHB concentrations were observed for the strain bearing the arcA2 allele, resulting in a PHB content of 35% +/- 3%. This strain grew in a simple medium at a specific growth rate of 0.69 +/- 0.07 h(-1), whereas the deletion mutant needed several nutritional additives and showed a specific growth rate of 0.56 +/- 0.06 h(-1). The results presented here suggest that arcA mutations could play a role in heterologous PHB synthesis in microaerobiosis.
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Affiliation(s)
- Pablo I Nikel
- Departamento de Química Biológica. Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria-Pabellón 2, 1428 Buenos Aires, Argentina
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