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Sharma A, Gupta S, Paul K. Codon usage behavior distinguishes pathogenic Clostridium species from the non-pathogenic species. Gene 2023; 873:147394. [PMID: 37137382 DOI: 10.1016/j.gene.2023.147394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/19/2023] [Accepted: 03/21/2023] [Indexed: 05/05/2023]
Abstract
Genus Clostridium is of the largest genus in class Clostridia. It is comprised of spore-forming, anaerobic, gram-positive organisms. The members of this genus include human pathogens to free-living nitrogen fixing bacteria. In the present study, we have performed a comparison of the choice of preferred codons, codon usage patterns, dinucleotide and amino acid usage pattern of 76 species of Genus Clostridium. We found the pathogenic clostridium species to have smaller AT-rich genomes as compared to opportunistic and non-pathogenic clostridium species. The choice of preferred and optimal codons was also influenced by genomic GC/AT content of the respective clostridium species. The pathogenic clostridium species displayed a strict bias in the codon usage, employing 35 of the 61 codons encoding for 20 amino acids. Comparison of amino acid usage revealed an increased usage of amino acids with lower biosynthetic cost by pathogenic clostridium species as compared to opportunistic and non-pathogenic clostridium species. Smaller genome, strict codon usage bias and amino acid usage lead to lower protein energetic cost for the clostridial pathogens. Overall, we found the pathogenic members of genus Clostridium to prefer small, AT-rich codons to reduce biosynthetic costs and match the cellular environment of its AT-rich human host.
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Affiliation(s)
- Anuj Sharma
- Department of Biochemistry, DAV University, Jalandhar, Punjab 144012, India
| | - Shelly Gupta
- Department of Biochemistry, School of Bioengineering and Biosciences, Lovely Professional University, Punjab 144411, India
| | - Karan Paul
- Department of Biochemistry, DAV University, Jalandhar, Punjab 144012, India.
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2
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Schroeder WL, Kuil T, van Maris AJA, Olson DG, Lynd LR, Maranas CD. A detailed genome-scale metabolic model of Clostridium thermocellum investigates sources of pyrophosphate for driving glycolysis. Metab Eng 2023; 77:306-322. [PMID: 37085141 DOI: 10.1016/j.ymben.2023.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/24/2023] [Accepted: 04/08/2023] [Indexed: 04/23/2023]
Abstract
Lignocellulosic biomass is an abundant and renewable source of carbon for chemical manufacturing, yet it is cumbersome in conventional processes. A promising, and increasingly studied, candidate for lignocellulose bioprocessing is the thermophilic anaerobe Clostridium thermocellum given its potential to produce ethanol, organic acids, and hydrogen gas from lignocellulosic biomass under high substrate loading. Possessing an atypical glycolytic pathway which substitutes GTP or pyrophosphate (PPi) for ATP in some steps, including in the energy-investment phase, identification, and manipulation of PPi sources are key to engineering its metabolism. Previous efforts to identify the primary pyrophosphate have been unsuccessful. Here, we explore pyrophosphate metabolism through reconstructing, updating, and analyzing a new genome-scale stoichiometric model for C. thermocellum, iCTH669. Hundreds of changes to the former GEM, iCBI655, including correcting cofactor usages, addressing charge and elemental balance, standardizing biomass composition, and incorporating the latest experimental evidence led to a MEMOTE score improvement to 94%. We found agreement of iCTH669 model predictions across all available fermentation and biomass yield datasets. The feasibility of hundreds of PPi synthesis routes, newly identified and previously proposed, were assessed through the lens of the iCTH669 model including biomass synthesis, tRNA synthesis, newly identified sources, and previously proposed PPi-generating cycles. In all cases, the metabolic cost of PPi synthesis is at best equivalent to investment of one ATP suggesting no direct energetic advantage for the cofactor substitution in C. thermocellum. Even though no unique source of PPi could be gleaned by the model, by combining with gene expression data two most likely scenarios emerge. First, previously investigated PPi sources likely account for most PPi production in wild-type strains. Second, alternate metabolic routes as encoded by iCTH669 can collectively maintain PPi levels even when previously investigated synthesis cycles are disrupted. Model iCTH669 is available at github.com/maranasgroup/iCTH669.
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Affiliation(s)
- Wheaton L Schroeder
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA; Center for Bioenergy Innovation, Oak Ridge, TN, USA
| | - Teun Kuil
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Antonius J A van Maris
- Department of Industrial Biotechnology, School of Engineering Sciences in Chemistry Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Daniel G Olson
- Center for Bioenergy Innovation, Oak Ridge, TN, USA; Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Lee R Lynd
- Center for Bioenergy Innovation, Oak Ridge, TN, USA; Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Costas D Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA; Center for Bioenergy Innovation, Oak Ridge, TN, USA.
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3
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Oarga A, Bannerman BP, Júlvez J. CONTRABASS: exploiting flux constraints in genome-scale models for the detection of vulnerabilities. Bioinformatics 2023; 39:7000333. [PMID: 36692133 PMCID: PMC9907045 DOI: 10.1093/bioinformatics/btad053] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 11/16/2022] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
MOTIVATION Despite the fact that antimicrobial resistance is an increasing health concern, the pace of production of new drugs is slow due to the high cost and uncertain success of the process. The development of high-throughput technologies has allowed the integration of biological data into detailed genome-scale models of multiple organisms. Such models can be exploited by means of computational methods to identify system vulnerabilities such as chokepoint reactions and essential reactions. These vulnerabilities are appealing drug targets that can lead to novel drug developments. However, the current approach to compute these vulnerabilities is only based on topological data and ignores the dynamic information of the model. This can lead to misidentified drug targets. RESULTS This work computes flux constraints that are consistent with a certain growth rate of the modelled organism, and integrates the computed flux constraints into the model to improve the detection of vulnerabilities. By exploiting these flux constraints, we are able to obtain a directionality of the reactions of metabolism consistent with a given growth rate of the model, and consequently, a more realistic detection of vulnerabilities can be performed. Several sets of reactions that are system vulnerabilities are defined and the relationships among them are studied. The approach for the detection of these vulnerabilities has been implemented in the Python tool CONTRABASS. Such tool, for which an online web server has also been implemented, computes flux constraints and generates a report with the detected vulnerabilities. AVAILABILITY AND IMPLEMENTATION CONTRABASS is available as an open source Python package at https://github.com/openCONTRABASS/CONTRABASS under GPL-3.0 License. An online web server is available at http://contrabass.unizar.es. SUPPLEMENTARY INFORMATION A glossary of terms are available at Bioinformatics online.
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Affiliation(s)
- Alexandru Oarga
- Department of Computer Science and Systems Engineering, University of Zaragoza, Zaragoza 50018, Spain
| | - Bridget P Bannerman
- Lucy Cavendish College, Biological Sciences, University of Cambridge, Cambridge CB3 0BU, UK.,Science Resources Foundation, Health Unit, London EC1V 2NX, UK
| | - Jorge Júlvez
- Department of Computer Science and Systems Engineering, University of Zaragoza, Zaragoza 50018, Spain
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4
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Functional analysis of H +-pumping membrane-bound pyrophosphatase, ADP-glucose synthase, and pyruvate phosphate dikinase as pyrophosphate sources in Clostridium thermocellum. Appl Environ Microbiol 2021; 88:e0185721. [PMID: 34936842 PMCID: PMC8863071 DOI: 10.1128/aem.01857-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The atypical glycolysis of Clostridium thermocellum is characterized by the use of pyrophosphate (PPi) as phosphoryl donor for phosphofructokinase (Pfk) and pyruvate phosphate dikinase (Ppdk) reactions. Previously, biosynthetic PPi was calculated to be stoichiometrically insufficient to drive glycolysis. This study investigates the role of a H+-pumping membrane-bound pyrophosphatase, glycogen cycling, a predicted Ppdk-malate shunt cycle and acetate cycling in generating PPi. Knockout studies and enzyme assays confirmed that clo1313_0823 encodes a membrane-bound pyrophosphatase. Additionally, clo1313_0717-0718 was confirmed to encode ADP-glucose synthase by knockouts, glycogen measurements in C. thermocellum and heterologous expression in E. coli. Unexpectedly, individually-targeted gene deletions of the four putative PPi sources did not have a significant phenotypic effect. Although combinatorial deletion of all four putative PPi sources reduced the growth rate by 22% (0.30±0.01 h-1) and the biomass yield by 38% (0.18±0.00 gbiomass gsubstrate-1), this change was much smaller than what would be expected for stoichiometrically essential PPi-supplying mechanisms. Growth-arrested cells of the quadruple knockout readily fermented cellobiose indicating that the unknown PPi-supplying mechanisms are independent of biosynthesis. An alternative hypothesis that ATP-dependent Pfk activity circumvents a need for PPi altogether, was falsified by enzyme assays, heterologous expression of candidate genes and whole-genome sequencing. As a secondary outcome, enzymatic assays confirmed functional annotation of clo1313_1832 as ATP- and GTP-dependent fructokinase. These results indicate that the four investigated PPi sources individually and combined play no significant PPi-supplying role and the true source(s) of PPi, or alternative phosphorylating mechanisms, that drive glycolysis in C. thermocellum remain(s) elusive. IMPORTANCE Increased understanding of the central metabolism of C. thermocellum is important from a fundamental as well as from a sustainability and industrial perspective. In addition to showing that H+-pumping membrane-bound PPase, glycogen cycling, a Ppdk-malate shunt cycle, and acetate cycling are not significant sources of PPi supply, this study adds functional annotation of four genes and availability of an updated PPi stoichiometry from biosynthesis to the scientific domain. Together, this aids future metabolic engineering attempts aimed to improve C. thermocellum as a cell factory for sustainable and efficient production of ethanol from lignocellulosic material through consolidated bioprocessing with minimal pretreatment. Getting closer to elucidating the elusive source of PPi, or alternative phosphorylating mechanisms, for the atypical glycolysis is itself of fundamental importance. Additionally, the findings of this study directly contribute to investigations into trade-offs between thermodynamic driving force versus energy yield of PPi- and ATP-dependent glycolysis.
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Lai CY, Zhou L, Yuan Z, Guo J. Hydrogen-driven microbial biogas upgrading: Advances, challenges and solutions. WATER RESEARCH 2021; 197:117120. [PMID: 33862393 DOI: 10.1016/j.watres.2021.117120] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/12/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
As a clean and renewable energy, biogas is an important alternative to fossil fuels. However, the high carbon dioxide (CO2) content in biogas limits its value as a fuel. 'Biogas upgrading' is an advanced process which removes CO2 from biogas, thereby converting biogas to biomethane, which has a higher commercial value. Microbial technologies offer a sustainable and cost-effective way to upgrade biogas, removing CO2 using hydrogen (H2) as electron donor, generated by surplus electricity from renewable wind or solar energy. Hydrogenotrophic methanogens can be applied to convert CO2 with H2 to methane (CH4), or alternatively, homoacetogens can convert both CO2 and H2 into value-added chemicals. Here, we comprehensively review the current state of biogas generation and utilization, and describe the advances in biological, H2-dependent biogas upgrading technologies, with particular attention to key challenges associated with the processes, e.g., metabolic limitations, low H2 transfer rate, and finite CO2 conversion rate. We also highlight several new strategies for overcoming technical barriers to achieve efficient CO2 conversion, including process optimization to eliminate metabolic limitation, novel reactor designs to improve H2 transfer rate and utilization efficiency, and employing advanced genetic engineering tools to generate more efficient microorganisms. The insights offered in this review will promote further exploration into microbial, H2-driven biogas upgrading, towards addressing the global energy crisis and climate change associated with use of fossil fuels.
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Affiliation(s)
- Chun-Yu Lai
- Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Linjie Zhou
- Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
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6
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Vees CA, Neuendorf CS, Pflügl S. Towards continuous industrial bioprocessing with solventogenic and acetogenic clostridia: challenges, progress and perspectives. J Ind Microbiol Biotechnol 2020; 47:753-787. [PMID: 32894379 PMCID: PMC7658081 DOI: 10.1007/s10295-020-02296-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022]
Abstract
The sustainable production of solvents from above ground carbon is highly desired. Several clostridia naturally produce solvents and use a variety of renewable and waste-derived substrates such as lignocellulosic biomass and gas mixtures containing H2/CO2 or CO. To enable economically viable production of solvents and biofuels such as ethanol and butanol, the high productivity of continuous bioprocesses is needed. While the first industrial-scale gas fermentation facility operates continuously, the acetone-butanol-ethanol (ABE) fermentation is traditionally operated in batch mode. This review highlights the benefits of continuous bioprocessing for solvent production and underlines the progress made towards its establishment. Based on metabolic capabilities of solvent producing clostridia, we discuss recent advances in systems-level understanding and genome engineering. On the process side, we focus on innovative fermentation methods and integrated product recovery to overcome the limitations of the classical one-stage chemostat and give an overview of the current industrial bioproduction of solvents.
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Affiliation(s)
- Charlotte Anne Vees
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Christian Simon Neuendorf
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Stefan Pflügl
- Institute of Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060 Vienna, Austria
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7
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Garcia S, Thompson RA, Giannone RJ, Dash S, Maranas CD, Trinh CT. Development of a Genome-Scale Metabolic Model of Clostridium thermocellum and Its Applications for Integration of Multi-Omics Datasets and Computational Strain Design. Front Bioeng Biotechnol 2020; 8:772. [PMID: 32974289 PMCID: PMC7471609 DOI: 10.3389/fbioe.2020.00772] [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: 04/02/2020] [Accepted: 06/18/2020] [Indexed: 01/29/2023] Open
Abstract
Solving environmental and social challenges such as climate change requires a shift from our current non-renewable manufacturing model to a sustainable bioeconomy. To lower carbon emissions in the production of fuels and chemicals, plant biomass feedstocks can replace petroleum using microorganisms as biocatalysts. The anaerobic thermophile Clostridium thermocellum is a promising bacterium for bioconversion due to its capability to efficiently degrade lignocellulosic biomass. However, the complex metabolism of C. thermocellum is not fully understood, hindering metabolic engineering to achieve high titers, rates, and yields of targeted molecules. In this study, we developed an updated genome-scale metabolic model of C. thermocellum that accounts for recent metabolic findings, has improved prediction accuracy, and is standard-conformant to ensure easy reproducibility. We illustrated two applications of the developed model. We first formulated a multi-omics integration protocol and used it to understand redox metabolism and potential bottlenecks in biofuel (e.g., ethanol) production in C. thermocellum. Second, we used the metabolic model to design modular cells for efficient production of alcohols and esters with broad applications as flavors, fragrances, solvents, and fuels. The proposed designs not only feature intuitive push-and-pull metabolic engineering strategies, but also present novel manipulations around important central metabolic branch-points. We anticipate the developed genome-scale metabolic model will provide a useful tool for system analysis of C. thermocellum metabolism to fundamentally understand its physiology and guide metabolic engineering strategies to rapidly generate modular production strains for effective biosynthesis of biofuels and biochemicals from lignocellulosic biomass.
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Affiliation(s)
- Sergio Garcia
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, United States.,Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - R Adam Thompson
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, United States.,Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Richard J Giannone
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Satyakam Dash
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Costas D Maranas
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, United States.,Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, United States.,Oak Ridge National Laboratory, Oak Ridge, TN, United States
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8
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Ou J, Bao T, Ernst P, Si Y, Prabhu SD, Wu H, Zhang J(J, Zhou L, Yang ST, Liu X(M. Intracellular metabolism analysis of Clostridium cellulovorans via modeling integrating proteomics, metabolomics and fermentation. Process Biochem 2020. [DOI: 10.1016/j.procbio.2019.10.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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9
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Lillington SP, Leggieri PA, Heom KA, O'Malley MA. Nature's recyclers: anaerobic microbial communities drive crude biomass deconstruction. Curr Opin Biotechnol 2019; 62:38-47. [PMID: 31593910 DOI: 10.1016/j.copbio.2019.08.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/25/2019] [Accepted: 08/29/2019] [Indexed: 12/13/2022]
Abstract
Microbial communities within anaerobic ecosystems have evolved to degrade and recycle carbon throughout the earth. A number of strains have been isolated from anaerobic microbial communities, which are rich in carbohydrate active enzymes (CAZymes) to liberate fermentable sugars from crude plant biomass (lignocellulose). However, natural anaerobic communities host a wealth of microbial diversity that has yet to be harnessed for biotechnological applications to hydrolyze crude biomass into sugars and value-added products. This review highlights recent advances in 'omics' techniques to sequence anaerobic microbial genomes, decipher microbial membership, and characterize CAZyme diversity in anaerobic microbiomes. With a focus on the herbivore rumen, we further discuss methods to discover new CAZymes, including those found within multi-enzyme fungal cellulosomes. Emerging techniques to characterize the interwoven metabolism and spatial interactions between anaerobes are also reviewed, which will prove critical to developing a predictive understanding of anaerobic communities to guide in microbiome engineering.
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Affiliation(s)
- Stephen P Lillington
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, United States
| | - Patrick A Leggieri
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, United States
| | - Kellie A Heom
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, United States
| | - Michelle A O'Malley
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, United States.
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10
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Röhl A, Bockmayr A. Finding MEMo: minimum sets of elementary flux modes. J Math Biol 2019; 79:1749-1777. [PMID: 31388689 DOI: 10.1007/s00285-019-01409-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 07/15/2019] [Indexed: 10/26/2022]
Abstract
Metabolic network reconstructions are widely used in computational systems biology for in silico studies of cellular metabolism. A common approach to analyse these models are elementary flux modes (EFMs), which correspond to minimal functional units in the network. Already for medium-sized networks, it is often impossible to compute the set of all EFMs, due to their huge number. From a practical point of view, this might also not be necessary because a subset of EFMs may already be sufficient to answer relevant biological questions. In this article, we study MEMos or minimum sets of EFMs that can generate all possible steady-state behaviours of a metabolic network. The number of EFMs in a MEMo may be by several orders of magnitude smaller than the total number of EFMs. Using MEMos, we can compute generating sets of EFMs in metabolic networks where the whole set of EFMs is too large to be enumerated.
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Affiliation(s)
- Annika Röhl
- Department of Mathematics and Computer Science, Freie Universität Berlin, Arnimallee 6, 14195, Berlin, Germany.
| | - Alexander Bockmayr
- Department of Mathematics and Computer Science, Freie Universität Berlin, Arnimallee 6, 14195, Berlin, Germany
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11
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Yan Q, Robert S, Brooks JP, Fong SS. Metabolic characterization of the chitinolytic bacterium Serratia marcescens using a genome-scale metabolic model. BMC Bioinformatics 2019; 20:227. [PMID: 31060515 PMCID: PMC6501404 DOI: 10.1186/s12859-019-2826-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 04/17/2019] [Indexed: 12/31/2022] Open
Abstract
Background Serratia marcescens is a chitinolytic bacterium that can potentially be used for consolidated bioprocessing to convert chitin to value-added chemicals. Currently, S. marcescens is poorly characterized and studies on intracellular metabolic and regulatory mechanisms would expedite development of bioprocessing applications. Results In this study, our goal was to characterize the metabolic profile of S. marcescens to provide insight for metabolic engineering applications and fundamental biological studies. Hereby, we constructed a constraint-based genome-scale metabolic model (iSR929) including 929 genes, 1185 reactions and 1164 metabolites based on genomic annotation of S. marcescens Db11. The model was tested by comparing model predictions with experimental data and analyzed to identify essential aspects of the metabolic network (e.g. 138 essential genes predicted). The model iSR929 was refined by integrating RNAseq data of S. marcescens growth on three different carbon sources (glucose, N-acetylglucosamine, and glycerol). Significant differences in TCA cycle utilization were found for growth on the different carbon substrates, For example, for growth on N-acetylglucosamine, S. marcescens exhibits high pentose phosphate pathway activity and nucleotide synthesis but low activity of the TCA cycle. Conclusions Our results show that S. marcescens model iSR929 can provide reasonable predictions and can be constrained to fit with experimental values. Thus, our model may be used to guide strain designs for metabolic engineering to produce chemicals such as 2,3-butanediol, N-acetylneuraminic acid, and n-butanol using S. marcescens. Electronic supplementary material The online version of this article (10.1186/s12859-019-2826-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Qiang Yan
- Department of Chemical and Life Science Engineering, School of Engineering, Virginia Commonwealth University, West Hall, Room 422, 601 West Main Street, P.O. Box 843028, Richmond, VA, 23284-3028, USA.
| | - Seth Robert
- Department of Chemical and Life Science Engineering, School of Engineering, Virginia Commonwealth University, West Hall, Room 422, 601 West Main Street, P.O. Box 843028, Richmond, VA, 23284-3028, USA
| | - J Paul Brooks
- Department of Statistical Sciences and Operations Research, Virginia Commonwealth University, P.O. Box 843083, Richmond, VA, 23284, USA.,Center for the study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Stephen S Fong
- Department of Chemical and Life Science Engineering, School of Engineering, Virginia Commonwealth University, West Hall, Room 422, 601 West Main Street, P.O. Box 843028, Richmond, VA, 23284-3028, USA. .,Center for the study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, 23284, USA.
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12
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Yaşar Yildiz S, Nikerel E, Toksoy Öner E. Genome-Scale Metabolic Model of a Microbial Cell Factory ( Brevibacillus thermoruber 423) with Multi-Industry Potentials for Exopolysaccharide Production. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2019; 23:237-246. [PMID: 30932743 DOI: 10.1089/omi.2019.0028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Brevibacillus thermoruber 423 is a thermophilic bacterium capable of producing high levels of exopolysaccharide (EPS) that has broad applications in nutrition, feed, cosmetics, pharmaceutical, and chemical industries, not to mention in health and bionanotechnology sectors. EPS is a natural, nontoxic, and biodegradable polymer of sugar residues and plays pivotal roles in cell-to-cell interactions, adhesion, biofilm formation, and protection of cell against environmental extremes. This bacterium is a thermophilic EPS producer while exceeding other thermophilic producers by virtue of high level of polymer synthesis. Recently, B. thermoruber 423 was noted for relevance to multiple industry sectors because of its capacity to use xylose, and produce EPS, isoprenoids, ethanol/butanol, lipases, proteases, cellulase, and glucoamylase enzymes as well as its resistance to arsenic. A key step in understanding EPS production with a systems-based approach is the knowledge of microbial genome sequence. To speed biotechnology and industrial applications, this study reports on a genome-scale metabolic model (GSMM) of B. thermoruber 423, constructed using the recently available high-quality genome sequence that we have subsequently validated using physiological data on batch growth and EPS production on seven different carbon sources. The model developed contains 1454 reactions (of which 1127 are assigned an enzyme commission number) and 1410 metabolites from 925 genes. This GSMM offers the promise to enable and accelerate further systems biology and industrial scale studies, not to mention the ability to calculate metabolic flux distribution in large networks and multiomic data integration.
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Affiliation(s)
- Songül Yaşar Yildiz
- 1 Department of Bioengineering, Istanbul Medeniyet University, Istanbul, Turkey
| | - Emrah Nikerel
- 2 Department of Genetics and Bioengineering, Yeditepe University, Istanbul, Turkey
| | - Ebru Toksoy Öner
- 3 Department of Bioengineering, IBSB, Marmara University, Istanbul, Turkey
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13
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Recent Advancements in Mycodegradation of Lignocellulosic Biomass for Bioethanol Production. Fungal Biol 2019. [DOI: 10.1007/978-3-030-23834-6_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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14
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Serrano-Bermúdez LM, González Barrios AF, Montoya D. Clostridium butyricum population balance model: Predicting dynamic metabolic flux distributions using an objective function related to extracellular glycerol content. PLoS One 2018; 13:e0209447. [PMID: 30571717 PMCID: PMC6301710 DOI: 10.1371/journal.pone.0209447] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/05/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Extensive experimentation has been conducted to increment 1,3-propanediol (PDO) production using Clostridium butyricum cultures in glycerol, but computational predictions are limited. Previously, we reconstructed the genome-scale metabolic (GSM) model iCbu641, the first such model of a PDO-producing Clostridium strain, which was validated at steady state using flux balance analysis (FBA). However, the prediction ability of FBA is limited for batch and fed-batch cultures, which are the most often employed industrial processes. RESULTS We used the iCbu641 GSM model to develop a dynamic flux balance analysis (DFBA) approach to predict the PDO production of the Colombian strain Clostridium sp IBUN 158B. First, we compared the predictions of the dynamic optimization approach (DOA), static optimization approach (SOA), and direct approach (DA). We found no differences between approaches, but the DOA simulation duration was nearly 5000 times that of the SOA and DA simulations. Experimental results at glycerol limitation and glycerol excess allowed for validating dynamic predictions of growth, glycerol consumption, and PDO formation. These results indicated a 4.4% error in PDO prediction and therefore validated the previously proposed objective functions. We performed two global sensitivity analyses, finding that the kinetic input parameters of glycerol uptake flux had the most significant effect on PDO predictions. The other input parameters evaluated during global sensitivity analysis were biomass composition (precursors and macromolecules), death constants, and the kinetic parameters of acetic acid secretion flux. These last input parameters, all obtained from other Clostridium butyricum cultures, were used to develop a population balance model (PBM). Finally, we simulated fed-batch cultures, predicting a final PDO production near to 66 g/L, almost three times the PDO predicted in the best batch culture. CONCLUSIONS We developed and validated a dynamic approach to predict PDO production using the iCbu641 GSM model and the previously proposed objective functions. This validated approach was used to propose a population model and then an increment in predictions of PDO production through fed-batch cultures. Therefore, this dynamic model could predict different scenarios, including its integration into downstream processes to predict technical-economic feasibilities and reducing the time and costs associated with experimentation.
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Affiliation(s)
- Luis Miguel Serrano-Bermúdez
- Bioprocesses and Bioprospecting Group, Universidad Nacional de Colombia, Ciudad Universitaria, Carrera, Bogotá D.C., Colombia
- Grupo Cundinamarca Agroambiental, Departamento de Ingeniería Ambiental, Universidad de Cundinamarca, Facatativá, Colombia
| | - Andrés Fernando González Barrios
- Grupo de Diseño de Productos y Procesos (GDPP), Departamento de Ingeniería Química, Universidad de los Andes, Bogotá D.C., Colombia
| | - Dolly Montoya
- Bioprocesses and Bioprospecting Group, Universidad Nacional de Colombia, Ciudad Universitaria, Carrera, Bogotá D.C., Colombia
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Xiong W, Lo J, Chou KJ, Wu C, Magnusson L, Dong T, Maness P. Isotope-Assisted Metabolite Analysis Sheds Light on Central Carbon Metabolism of a Model Cellulolytic Bacterium Clostridium thermocellum. Front Microbiol 2018; 9:1947. [PMID: 30190711 PMCID: PMC6115520 DOI: 10.3389/fmicb.2018.01947] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/31/2018] [Indexed: 01/01/2023] Open
Abstract
Cellulolytic bacteria have the potential to perform lignocellulose hydrolysis and fermentation simultaneously. The metabolic pathways of these bacteria, therefore, require more comprehensive and quantitative understanding. Using isotope tracer, gas chromatography-mass spectrometry, and metabolic flux modeling, we decipher the metabolic network of Clostridium thermocellum, a model cellulolytic bacterium which represents as an attractive platform for conversion of lignocellulose to dedicated products. We uncover that the Embden-Meyerhof-Parnas (EMP) pathway is the predominant glycolytic route whereas the Entner-Doudoroff (ED) pathway and oxidative pentose phosphate pathway are inactive. We also observe that C. thermocellum's TCA cycle is initiated by both Si- and Re-citrate synthase, and it is disconnected between 2-oxoglutarate and oxaloacetate in the oxidative direction; C. thermocellum uses a citramalate shunt to synthesize isoleucine; and both the one-carbon pathway and the malate shunt are highly active in this bacterium. To gain a quantitative understanding, we further formulate a fluxome map to quantify the metabolic fluxes through central metabolic pathways. This work represents the first global in vivo investigation of the principal carbon metabolism of C. thermocellum. Our results elucidate the unique structure of metabolic network in this cellulolytic bacterium and demonstrate the capability of isotope-assisted metabolite studies in understanding microbial metabolism of industrial interests.
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Affiliation(s)
- Wei Xiong
- National Renewable Energy Laboratory, Golden, CO, United States
| | - Jonathan Lo
- National Renewable Energy Laboratory, Golden, CO, United States
| | | | - Chao Wu
- National Renewable Energy Laboratory, Golden, CO, United States
| | | | - Tao Dong
- National Renewable Energy Laboratory, Golden, CO, United States
| | - PinChing Maness
- National Renewable Energy Laboratory, Golden, CO, United States
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16
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Production of optically pure 2,3-butanediol from Miscanthus floridulus hydrolysate using engineered Bacillus licheniformis strains. World J Microbiol Biotechnol 2018; 34:66. [PMID: 29687256 DOI: 10.1007/s11274-018-2450-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 04/18/2018] [Indexed: 01/02/2023]
Abstract
2,3-Butanediol (2,3-BD) can be produced by fermentation of natural resources like Miscanthus. Bacillus licheniformis mutants, WX-02ΔbudC and WX-02ΔgldA, were elucidated for the potential to use Miscanthus as a cost-effective biomass to produce optically pure 2,3-BD. Both WX-02ΔbudC and WX-02ΔgldA could efficiently use xylose as well as mixed sugars of glucose and xylose to produce optically pure 2,3-BD. Batch fermentation of M. floridulus hydrolysate could produce 21.6 g/L D-2,3-BD and 23.9 g/L meso-2,3-BD in flask, and 13.8 g/L D-2,3-BD and 13.2 g/L meso-2,3-BD in bioreactor for WX-02ΔbudC and WX-02ΔgldA, respectively. Further fed-batch fermentation of hydrolysate in bioreactor showed both of two strains could produce optically pure 2,3-BD, with 32.2 g/L D-2,3-BD for WX-02ΔbudC and 48.5 g/L meso-2,3-BD for WX-02ΔgldA, respectively. Collectively, WX-02ΔbudC and WX-02ΔgldA can efficiently produce optically pure 2,3-BD with M. floridulus hydrolysate, and these two strains are candidates for industrial production of optical purity of 2,3-BD with M. floridulus hydrolysate.
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17
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Pinu FR, Granucci N, Daniell J, Han TL, Carneiro S, Rocha I, Nielsen J, Villas-Boas SG. Metabolite secretion in microorganisms: the theory of metabolic overflow put to the test. Metabolomics 2018; 14:43. [PMID: 30830324 DOI: 10.1007/s11306-018-1339-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/07/2018] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Microbial cells secrete many metabolites during growth, including important intermediates of the central carbon metabolism. This has not been taken into account by researchers when modeling microbial metabolism for metabolic engineering and systems biology studies. MATERIALS AND METHODS The uptake of metabolites by microorganisms is well studied, but our knowledge of how and why they secrete different intracellular compounds is poor. The secretion of metabolites by microbial cells has traditionally been regarded as a consequence of intracellular metabolic overflow. CONCLUSIONS Here, we provide evidence based on time-series metabolomics data that microbial cells eliminate some metabolites in response to environmental cues, independent of metabolic overflow. Moreover, we review the different mechanisms of metabolite secretion and explore how this knowledge can benefit metabolic modeling and engineering.
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Affiliation(s)
- Farhana R Pinu
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92169, Auckland, 1142, New Zealand.
| | - Ninna Granucci
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
| | - James Daniell
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
- LanzaTech, Skokie, IL, 60077, USA
| | - Ting-Li Han
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
| | - Sonia Carneiro
- Center of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Isabel Rocha
- Center of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivagen 10, 412 96, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2970, Hørsholm, Denmark
| | - Silas G Villas-Boas
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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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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Kaushal M, Chary KVN, Ahlawat S, Palabhanvi B, Goswami G, Das D. Understanding regulation in substrate dependent modulation of growth and production of alcohols in Clostridium sporogenes NCIM 2918 through metabolic network reconstruction and flux balance analysis. BIORESOURCE TECHNOLOGY 2018; 249:767-776. [PMID: 29136931 DOI: 10.1016/j.biortech.2017.10.080] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/18/2017] [Accepted: 10/20/2017] [Indexed: 06/07/2023]
Abstract
Flux Balance Analysis was performed for Clostridium sporogenes NCIM 2918 grown on sole glucose and glycerol or glucose-glycerol combinations at varied concentrations. During acidogenesis, glucose and glucose-glycerol combinations favored improved growth and butyric acid production. Glycerol fermentation was however marked by reduced growth and predominant ethanol synthesis. Further, with increase of glycerol fraction in glucose-glycerol blend, flux towards ethanol synthesis linearly increased with simultaneous decrease in butanol flux. Elevated ATP demand due to improved growth was satisfied by upregulated carbon flux towards butyric acid synthesis during both glucose and dual substrate fermentations. Possible repression of pyruvate carboxylase by glycerol resulting in downturn of carbon uptake flux towards TCA cycle through anaplerotic reaction may be responsible for reduced growth in glycerol fermentation. Ammonium acetate mediated induction of acetic acid utilization, during acidogenesis, led to excess acetyl-CoA generation and its subsequent metabolism to lesser reduced products, butyric acid or ethanol.
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Affiliation(s)
- Mehak Kaushal
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, Assam 781039, India; DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - K Venkata Narayana Chary
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, Assam 781039, India; DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Saumya Ahlawat
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, Assam 781039, India; DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Basavaraj Palabhanvi
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, Assam 781039, India; DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Gargi Goswami
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, Assam 781039, India; DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Debasish Das
- Department of Biosciences & Bioengineering, Indian Institute of Technology, Guwahati, Assam 781039, India; DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology, Guwahati, Assam 781039, India.
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20
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Sangavai C, Chellapandi P. Amino acid catabolism-directed biofuel production in Clostridium sticklandii: An insight into model-driven systems engineering. ACTA ACUST UNITED AC 2017; 16:32-43. [PMID: 29167757 PMCID: PMC5686429 DOI: 10.1016/j.btre.2017.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/17/2017] [Accepted: 11/03/2017] [Indexed: 01/01/2023]
Abstract
Model-driven systems engineering has been more fascinating process for microbial biofuel production. Clostridium sticklandii is a potential strain for the solventogenesis and acidogenesis. The present review provides an insight for the protein catabolism-directed biofuel production.
Model-driven systems engineering has been more fascinating process for the microbial production of biofuel and bio-refineries in chemical and pharmaceutical industries. Genome-scale modeling and simulations have been guided for metabolic engineering of Clostridium species for the production of organic solvents and organic acids. Among them, Clostridium sticklandii is one of the potential organisms to be exploited as a microbial cell factory for biofuel production. It is a hyper-ammonia producing bacterium and is able to catabolize amino acids as important carbon and energy sources via Stickland reactions and the development of the specific pathways. Current genomic and metabolic aspects of this bacterium are comprehensively reviewed herein, which provided information for learning about protein catabolism-directed biofuel production. It has a metabolic potential to drive energy and direct solventogenesis as well as acidogenesis from protein catabolism. It produces by-products such as ethanol, acetate, n-butanol, n-butyrate and hydrogen from amino acid catabolism. Model-driven systems engineering of this organism would improve the performance of the industrial sectors and enhance the industrial economy by using protein-based waste in environment-friendly ways.
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Affiliation(s)
- C Sangavai
- Molecular Systems Engineering Lab, Department of Bioinformatics, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620 024, Tamil Nadu, India
| | - P Chellapandi
- Molecular Systems Engineering Lab, Department of Bioinformatics, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620 024, Tamil Nadu, India
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de Eugenio LI, Méndez-Líter JA, Nieto-Domínguez M, Alonso L, Gil-Muñoz J, Barriuso J, Prieto A, Martínez MJ. Differential β-glucosidase expression as a function of carbon source availability in Talaromyces amestolkiae: a genomic and proteomic approach. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:161. [PMID: 28649280 PMCID: PMC5481877 DOI: 10.1186/s13068-017-0844-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 06/08/2017] [Indexed: 05/07/2023]
Abstract
BACKGROUND Genomic and proteomic analysis are potent tools for metabolic characterization of microorganisms. Although cellulose usually triggers cellulase production in cellulolytic fungi, the secretion of the different enzymes involved in polymer conversion is subjected to different factors, depending on growth conditions. These enzymes are key factors in biomass exploitation for second generation bioethanol production. Although highly effective commercial cocktails are available, they are usually deficient for β-glucosidase activity, and genera like Penicillium and Talaromyces are being explored for its production. RESULTS This article presents the description of Talaromyces amestolkiae as a cellulase-producer fungus that secretes high levels of β-glucosidase. β-1,4-endoglucanase, exoglucanase, and β-glucosidase activities were quantified in the presence of different carbon sources. Although the two first activities were only induced with cellulosic substrates, β-glucosidase levels were similar in all carbon sources tested. Sequencing and analysis of the genome of this fungus revealed multiple genes encoding β-glucosidases. Extracellular proteome analysis showed different induction patterns. In all conditions assayed, glycosyl hydrolases were the most abundant proteins in the supernatants, albeit the ratio of the diverse enzymes from this family depended on the carbon source. At least two different β-glucosidases have been identified in this work: one is induced by cellulose and the other one is carbon source-independent. The crudes induced by Avicel and glucose were independently used as supplements for saccharification of slurry from acid-catalyzed steam-exploded wheat straw, obtaining the highest yields of fermentable glucose using crudes induced by cellulose. CONCLUSIONS The genome of T. amestolkiae contains several genes encoding β-glucosidases and the fungus secretes high levels of this activity, regardless of the carbon source availability, although its production is repressed by glucose. Two main different β-glucosidases have been identified from proteomic shotgun analysis. One of them is produced under different carbon sources, while the other is induced in cellulosic substrates and is a good supplement to Celluclast in saccharification of pretreated wheat straw.
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Affiliation(s)
- Laura I. de Eugenio
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Juan A. Méndez-Líter
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Manuel Nieto-Domínguez
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Lola Alonso
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
- Genetic and Molecular Epidemiology Group, Human Cancer Genetics Programme, Spanish National Cancer Research Centre, CNIO, Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Jesús Gil-Muñoz
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Jorge Barriuso
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Alicia Prieto
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - María Jesús Martínez
- Department of Environmental Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
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Serrano-Bermúdez LM, González Barrios AF, Maranas CD, Montoya D. Clostridium butyricum maximizes growth while minimizing enzyme usage and ATP production: metabolic flux distribution of a strain cultured in glycerol. BMC SYSTEMS BIOLOGY 2017; 11:58. [PMID: 28571567 PMCID: PMC5455137 DOI: 10.1186/s12918-017-0434-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 05/16/2017] [Indexed: 01/15/2023]
Abstract
BACKGROUND The increase in glycerol obtained as a byproduct of biodiesel has encouraged the production of new industrial products, such as 1,3-propanediol (PDO), using biotechnological transformation via bacteria like Clostridium butyricum. However, despite the increasing role of Clostridium butyricum as a bio-production platform, its metabolism remains poorly modeled. RESULTS We reconstructed iCbu641, the first genome-scale metabolic (GSM) model of a PDO producer Clostridium strain, which included 641 genes, 365 enzymes, 891 reactions, and 701 metabolites. We found an enzyme expression prediction of nearly 84% after comparison of proteomic data with flux distribution estimation using flux balance analysis (FBA). The remaining 16% corresponded to enzymes directionally coupled to growth, according to flux coupling findings (FCF). The fermentation data validation also revealed different phenotype states that depended on culture media conditions; for example, Clostridium maximizes its biomass yield per enzyme usage under glycerol limitation. By contrast, under glycerol excess conditions, Clostridium grows sub-optimally, maximizing biomass yield while minimizing both enzyme usage and ATP production. We further evaluated perturbations in the GSM model through enzyme deletions and variations in biomass composition. The GSM predictions showed no significant increase in PDO production, suggesting a robustness to perturbations in the GSM model. We used the experimental results to predict that co-fermentation was a better alternative than iCbu641 perturbations for improving PDO yields. CONCLUSIONS The agreement between the predicted and experimental values allows the use of the GSM model constructed for the PDO-producing Clostridium strain to propose new scenarios for PDO production, such as dynamic simulations, thereby reducing the time and costs associated with experimentation.
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Affiliation(s)
- Luis Miguel Serrano-Bermúdez
- Bioprocesses and Bioprospecting Group, Universidad Nacional de Colombia. Ciudad Universitaria, Carrera 30 No. 45-03, Bogotá, D.C Colombia
| | - Andrés Fernando González Barrios
- Grupo de Diseño de Productos y Procesos (GDPP), Departamento de Ingeniería Química, Universidad de los Andes, Carrera 1 N.° 18A – 12, Bogotá, Colombia
| | - Costas D. Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802 USA
| | - Dolly Montoya
- Bioprocesses and Bioprospecting Group, Universidad Nacional de Colombia. Ciudad Universitaria, Carrera 30 No. 45-03, Bogotá, D.C Colombia
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Ahmad A, Hartman HB, Krishnakumar S, Fell DA, Poolman MG, Srivastava S. A Genome Scale Model of Geobacillus thermoglucosidasius (C56-YS93) reveals its biotechnological potential on rice straw hydrolysate. J Biotechnol 2017; 251:30-37. [DOI: 10.1016/j.jbiotec.2017.03.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 03/27/2017] [Accepted: 03/27/2017] [Indexed: 01/29/2023]
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Dash S, Khodayari A, Zhou J, Holwerda EK, Olson DG, Lynd LR, Maranas CD. Development of a core Clostridium thermocellum kinetic metabolic model consistent with multiple genetic perturbations. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:108. [PMID: 28469704 PMCID: PMC5414155 DOI: 10.1186/s13068-017-0792-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Accepted: 04/18/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Clostridium thermocellum is a Gram-positive anaerobe with the ability to hydrolyze and metabolize cellulose into biofuels such as ethanol, making it an attractive candidate for consolidated bioprocessing (CBP). At present, metabolic engineering in C. thermocellum is hindered due to the incomplete description of its metabolic repertoire and regulation within a predictive metabolic model. Genome-scale metabolic (GSM) models augmented with kinetic models of metabolism have been shown to be effective at recapitulating perturbed metabolic phenotypes. RESULTS In this effort, we first update a second-generation genome-scale metabolic model (iCth446) for C. thermocellum by correcting cofactor dependencies, restoring elemental and charge balances, and updating GAM and NGAM values to improve phenotype predictions. The iCth446 model is next used as a scaffold to develop a core kinetic model (k-ctherm118) of the C. thermocellum central metabolism using the Ensemble Modeling (EM) paradigm. Model parameterization is carried out by simultaneously imposing fermentation yield data in lactate, malate, acetate, and hydrogen production pathways for 19 measured metabolites spanning a library of 19 distinct single and multiple gene knockout mutants along with 18 intracellular metabolite concentration data for a Δgldh mutant and ten experimentally measured Michaelis-Menten kinetic parameters. CONCLUSIONS The k-ctherm118 model captures significant metabolic changes caused by (1) nitrogen limitation leading to increased yields for lactate, pyruvate, and amino acids, and (2) ethanol stress causing an increase in intracellular sugar phosphate concentrations (~1.5-fold) due to upregulation of cofactor pools. Robustness analysis of k-ctherm118 alludes to the presence of a secondary activity of ketol-acid reductoisomerase and possible regulation by valine and/or leucine pool levels. In addition, cross-validation and robustness analysis allude to missing elements in k-ctherm118 and suggest additional experiments to improve kinetic model prediction fidelity. Overall, the study quantitatively assesses the advantages of EM-based kinetic modeling towards improved prediction of C. thermocellum metabolism and develops a predictive kinetic model which can be used to design biofuel-overproducing strains.
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Affiliation(s)
- Satyakam Dash
- Department of Chemical Engineering, The Pennsylvania State University, 126 Land and Water Research Building, University Park, PA 16802 USA
| | - Ali Khodayari
- Department of Chemical Engineering, The Pennsylvania State University, 126 Land and Water Research Building, University Park, PA 16802 USA
| | - Jilai Zhou
- Thayer School of Engineering at Dartmouth College, Hanover, NH USA
| | | | - Daniel G. Olson
- Thayer School of Engineering at Dartmouth College, Hanover, NH USA
| | - Lee R. Lynd
- Thayer School of Engineering at Dartmouth College, Hanover, NH USA
| | - Costas D. Maranas
- Department of Chemical Engineering, The Pennsylvania State University, 126 Land and Water Research Building, University Park, PA 16802 USA
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Taillefer M, Sparling R. Glycolysis as the Central Core of Fermentation. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017; 156:55-77. [PMID: 26907549 DOI: 10.1007/10_2015_5003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The increasing concerns of greenhouse gas emissions have increased the interest in dark fermentation as a means of productions for industrial chemicals, especially from renewable cellulosic biomass. However, the metabolism, including glycolysis, of many candidate organisms for cellulosic biomass conversion through consolidated bioprocessing is still poorly understood and the genomes have only recently been sequenced. Because a variety of industrial chemicals are produced directly from sugar metabolism, the careful understanding of glycolysis from a genomic and biochemical point of view is essential in the development of strategies for increasing product yields and therefore increasing industrial potential. The current review discusses the different pathways available for glycolysis along with unexpected variations from traditional models, especially in the utilization of alternate energy intermediates (GTP, pyrophosphate). This reinforces the need for a careful description of interactions between energy metabolites and glycolysis enzymes for understanding carbon and electron flux regulation.
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Affiliation(s)
- M Taillefer
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
| | - R Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2.
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Poudel S, Giannone RJ, Rodriguez M, Raman B, Martin MZ, Engle NL, Mielenz JR, Nookaew I, Brown SD, Tschaplinski TJ, Ussery D, Hettich RL. Integrated omics analyses reveal the details of metabolic adaptation of Clostridium thermocellum to lignocellulose-derived growth inhibitors released during the deconstruction of switchgrass. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:14. [PMID: 28077967 PMCID: PMC5223564 DOI: 10.1186/s13068-016-0697-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 12/24/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND Clostridium thermocellum is capable of solubilizing and converting lignocellulosic biomass into ethanol. Although much of the work-to-date has centered on characterizing this microbe's growth on model cellulosic substrates, such as cellobiose, Avicel, or filter paper, it is vitally important to understand its metabolism on more complex, lignocellulosic substrates to identify relevant industrial bottlenecks that could undermine efficient biofuel production. To this end, we have examined a time course progression of C. thermocellum grown on switchgrass to assess the metabolic and protein changes that occur during the conversion of plant biomass to ethanol. RESULTS The most striking feature of the metabolome was the observed accumulation of long-chain, branched fatty acids over time, implying an adaptive restructuring of C. thermocellum's cellular membrane as the culture progresses. This is undoubtedly a response to the gradual accumulation of lignocellulose-derived inhibitory compounds as the organism deconstructs the switchgrass to access the embedded cellulose. Corroborating the metabolomics data, proteomic analysis revealed a corresponding time-dependent increase in various enzymes, including those involved in the interconversion of branched amino acids valine, leucine, and isoleucine to iso- and anteiso-fatty acid precursors. Additionally, the metabolic accumulation of hemicellulose-derived sugars and sugar alcohols concomitant with increased abundance of enzymes involved in C5 sugar metabolism/pentose phosphate pathway indicates that C. thermocellum shifts glycolytic intermediates to alternate pathways to modulate overall carbon flux in response to C5 sugar metabolites that increase during lignocellulose deconstruction. CONCLUSIONS Integrated omic platforms provided complementary systems biological information that highlight C. thermocellum's specific response to cytotoxic inhibitors released during the deconstruction and utilization of switchgrass. These additional viewpoints allowed us to fully realize the level to which the organism adapts to an increasingly challenging culture environment-information that will prove critical to C. thermocellum's industrial efficacy.
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Affiliation(s)
- Suresh Poudel
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
- Department of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996 USA
| | | | - Miguel Rodriguez
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
| | - Babu Raman
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
- Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268 USA
| | - Madhavi Z. Martin
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
| | - Nancy L. Engle
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
| | | | - Intawat Nookaew
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR 72205 USA
| | - Steven D. Brown
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
- Department of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996 USA
| | | | - David Ussery
- Biosciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR 72205 USA
| | - Robert L. Hettich
- Chemical Sciences Division, Oak Ridge National Lab, Oak Ridge, TN 37831 USA
- Department of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996 USA
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Genome-Scale Modeling of Thermophilic Microorganisms. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016. [PMID: 27913830 DOI: 10.1007/10_2016_45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Thermophilic microorganisms are of increasing interest for many industries as their enzymes and metabolisms are highly efficient at elevated temperatures. However, their metabolic processes are often largely different from their mesophilic counterparts. These differences can lead to metabolic engineering strategies that are doomed to fail. Genome-scale metabolic modeling is an effective and highly utilized way to investigate cellular phenotypes and to test metabolic engineering strategies. In this review we chronicle a number of thermophilic organisms that have recently been studied with genome-scale models. The microorganisms spread across archaea and bacteria domains, and their study gives insights that can be applied in a broader context than just the species they describe. We end with a perspective on the future development and applications of genome-scale models of thermophilic organisms.
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Lo J, Olson DG, Murphy SJL, Tian L, Hon S, Lanahan A, Guss AM, Lynd LR. Engineering electron metabolism to increase ethanol production in Clostridium thermocellum. Metab Eng 2016; 39:71-79. [PMID: 27989806 DOI: 10.1016/j.ymben.2016.10.018] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 10/17/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
The NfnAB (NADH-dependent reduced ferredoxin: NADP+ oxidoreductase) and Rnf (ion-translocating reduced ferredoxin: NAD+ oxidoreductase) complexes are thought to catalyze electron transfer between reduced ferredoxin and NAD(P)+. Efficient electron flux is critical for engineering fuel production pathways, but little is known about the relative importance of these enzymes in vivo. In this study we investigate the importance of the NfnAB and Rnf complexes in Clostridium thermocellum for growth on cellobiose and Avicel using gene deletion, enzyme assays, and fermentation product analysis. The NfnAB complex does not seem to play a major role in metabolism, since deletion of nfnAB genes had little effect on the distribution of fermentation products. By contrast, the Rnf complex appears to play an important role in ethanol formation. Deletion of rnf genes resulted in a decrease in ethanol formation. Overexpression of rnf genes resulted in an increase in ethanol production of about 30%, but only in strains where the hydG hydrogenase maturation gene was also deleted.
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Affiliation(s)
- Jonathan Lo
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Sean Jean-Loup Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Liang Tian
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Shuen Hon
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Anthony Lanahan
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA
| | - Adam M Guss
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge TN 37830, USA.
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Thompson RA, Dahal S, Garcia S, Nookaew I, Trinh CT. Exploring complex cellular phenotypes and model-guided strain design with a novel genome-scale metabolic model of Clostridium thermocellum DSM 1313 implementing an adjustable cellulosome. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:194. [PMID: 27602057 PMCID: PMC5012057 DOI: 10.1186/s13068-016-0607-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/26/2016] [Indexed: 05/06/2023]
Abstract
BACKGROUND Clostridium thermocellum is a gram-positive thermophile that can directly convert lignocellulosic material into biofuels. The metabolism of C. thermocellum contains many branches and redundancies which limit biofuel production, and typical genetic techniques are time-consuming. Further, the genome sequence of a genetically tractable strain C. thermocellum DSM 1313 has been recently sequenced and annotated. Therefore, developing a comprehensive, predictive, genome-scale metabolic model of DSM 1313 is desired for elucidating its complex phenotypes and facilitating model-guided metabolic engineering. RESULTS We constructed a genome-scale metabolic model iAT601 for DSM 1313 using the KEGG database as a scaffold and an extensive literature review and bioinformatic analysis for model refinement. Next, we used several sets of experimental data to train the model, e.g., estimation of the ATP requirement for growth-associated maintenance (13.5 mmol ATP/g DCW/h) and cellulosome synthesis (57 mmol ATP/g cellulosome/h). Using our tuned model, we investigated the effect of cellodextrin lengths on cell yields, and could predict in silico experimentally observed differences in cell yield based on which cellodextrin species is assimilated. We further employed our tuned model to analyze the experimentally observed differences in fermentation profiles (i.e., the ethanol to acetate ratio) between cellobiose- and cellulose-grown cultures and infer regulatory mechanisms to explain the phenotypic differences. Finally, we used the model to design over 250 genetic modification strategies with the potential to optimize ethanol production, 6155 for hydrogen production, and 28 for isobutanol production. CONCLUSIONS Our developed genome-scale model iAT601 is capable of accurately predicting complex cellular phenotypes under a variety of conditions and serves as a high-quality platform for model-guided strain design and metabolic engineering to produce industrial biofuels and chemicals of interest.
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Affiliation(s)
- R. Adam Thompson
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN 37996 USA
- Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Sanjeev Dahal
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Comparative Genomics Group, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Sergio Garcia
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
| | - Intawat Nookaew
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Comparative Genomics Group, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Biomedical Informatics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205 USA
| | - Cong T. Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN 37996 USA
- Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 1512 Middle Dr., DO#432, Knoxville, TN 37996 USA
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Islam MA, Zengler K, Edwards EA, Mahadevan R, Stephanopoulos G. Investigating Moorella thermoacetica metabolism with a genome-scale constraint-based metabolic model. Integr Biol (Camb) 2016; 7:869-82. [PMID: 25994252 DOI: 10.1039/c5ib00095e] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Moorella thermoacetica is a strictly anaerobic, endospore-forming, and metabolically versatile acetogenic bacterium capable of conserving energy by both autotrophic (acetogenesis) and heterotrophic (homoacetogenesis) modes of metabolism. Its metabolic diversity and the ability to efficiently convert a wide range of compounds, including syngas (CO + H2) into acetyl-CoA have made this thermophilic bacterium a promising host for industrial biotechnology applications. However, lack of detailed information on M. thermoacetica's metabolism is a major impediment to its use as a microbial cell factory. In order to overcome this issue, a genome-scale constraint-based metabolic model of Moorella thermoacetica, iAI558, has been developed using its genome sequence and physiological data from published literature. The reconstructed metabolic network of M. thermoacetica comprises 558 metabolic genes, 705 biochemical reactions, and 698 metabolites. Of the total 705 model reactions, 680 are gene-associated while the rest are non-gene associated reactions. The model, in addition to simulating both autotrophic and heterotrophic growth of M. thermoacetica, revealed degeneracy in its TCA-cycle, a common characteristic of anaerobic metabolism. Furthermore, the model helped elucidate the poorly understood energy conservation mechanism of M. thermoacetica during autotrophy. Thus, in addition to generating experimentally testable hypotheses regarding its physiology, such a detailed model will facilitate rapid strain designing and metabolic engineering of M. thermoacetica for industrial applications.
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Affiliation(s)
- M Ahsanul Islam
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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31
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PSAMM: A Portable System for the Analysis of Metabolic Models. PLoS Comput Biol 2016; 12:e1004732. [PMID: 26828591 PMCID: PMC4734835 DOI: 10.1371/journal.pcbi.1004732] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 01/05/2016] [Indexed: 11/19/2022] Open
Abstract
The genome-scale models of metabolic networks have been broadly applied in phenotype prediction, evolutionary reconstruction, community functional analysis, and metabolic engineering. Despite the development of tools that support individual steps along the modeling procedure, it is still difficult to associate mathematical simulation results with the annotation and biological interpretation of metabolic models. In order to solve this problem, here we developed a Portable System for the Analysis of Metabolic Models (PSAMM), a new open-source software package that supports the integration of heterogeneous metadata in model annotations and provides a user-friendly interface for the analysis of metabolic models. PSAMM is independent of paid software environments like MATLAB, and all its dependencies are freely available for academic users. Compared to existing tools, PSAMM significantly reduced the running time of constraint-based analysis and enabled flexible settings of simulation parameters using simple one-line commands. The integration of heterogeneous, model-specific annotation information in PSAMM is achieved with a novel format of YAML-based model representation, which has several advantages, such as providing a modular organization of model components and simulation settings, enabling model version tracking, and permitting the integration of multiple simulation problems. PSAMM also includes a number of quality checking procedures to examine stoichiometric balance and to identify blocked reactions. Applying PSAMM to 57 models collected from current literature, we demonstrated how the software can be used for managing and simulating metabolic models. We identified a number of common inconsistencies in existing models and constructed an updated model repository to document the resolution of these inconsistencies. The broad application of genome-scale metabolic modeling has made it a useful technique for tackling fundamental questions in biological research and engineering. Today over 100 models have been constructed for organisms that carry out a diverse array of metabolic activities spanning all three kingdoms of life. These models, however, have been curated independently following different conventions. The maintenance of model consistency has been challenging due to the lack of consensus in model representation and the absence of integrated modeling software for associating mathematical simulations with the annotation and biological interpretation of metabolic models. To solve this problem, we developed a new software package, PSAMM, and a new model format that incorporates heterogeneous, model-specific annotation information into modular representations of model definitions and simulation settings. PSAMM provides significant advances in standardizing the workflow of model annotation and consistency checking. Compared to existing tools, PSAMM supports more flexible configurations and is more efficient in running constraint-based simulations. All functions of PSAMM are freely available for academic users and can be downloaded from a public Git repository (https://zhanglab.github.io/psamm/) under the GNU General Public License.
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32
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Dash S, Ng CY, Maranas CD. Metabolic modeling of clostridia: current developments and applications. FEMS Microbiol Lett 2016; 363:fnw004. [PMID: 26755502 DOI: 10.1093/femsle/fnw004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2016] [Indexed: 12/12/2022] Open
Abstract
Anaerobic Clostridium spp. is an important bioproduction microbial genus that can produce solvents and utilize a broad spectrum of substrates including cellulose and syngas. Genome-scale metabolic (GSM) models are increasingly being put forth for various clostridial strains to explore their respective metabolic capabilities and suitability for various bioconversions. In this study, we have selected representative GSM models for six different clostridia (Clostridium acetobutylicum, C. beijerinckii, C. butyricum, C. cellulolyticum, C. ljungdahlii and C. thermocellum) and performed a detailed model comparison contrasting their metabolic repertoire. We also discuss various applications of these GSM models to guide metabolic engineering interventions as well as assessing cellular physiology.
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Affiliation(s)
- Satyakam Dash
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802-1503, USA
| | - Chiam Yu Ng
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802-1503, USA
| | - Costas D Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802-1503, USA
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Deng K, Takasuka TE, Bianchetti CM, Bergeman LF, Adams PD, Northen TR, Fox BG. Use of Nanostructure-Initiator Mass Spectrometry to Deduce Selectivity of Reaction in Glycoside Hydrolases. Front Bioeng Biotechnol 2015; 3:165. [PMID: 26579511 PMCID: PMC4621489 DOI: 10.3389/fbioe.2015.00165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/02/2015] [Indexed: 12/20/2022] Open
Abstract
Chemically synthesized nanostructure-initiator mass spectrometry (NIMS) probes derivatized with tetrasaccharides were used to study the reactivity of representative Clostridium thermocellum β-glucosidase, endoglucanases, and cellobiohydrolase. Diagnostic patterns for reactions of these different classes of enzymes were observed. Results show sequential removal of glucose by the β-glucosidase and a progressive increase in specificity of reaction from endoglucanases to cellobiohydrolase. Time-dependent reactions of these polysaccharide-selective enzymes were modeled by numerical integration, which provides a quantitative basis to make functional distinctions among a continuum of naturally evolved catalytic properties. Consequently, our method, which combines automated protein translation with high-sensitivity and time-dependent detection of multiple products, provides a new approach to annotate glycoside hydrolase phylogenetic trees with functional measurements.
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Affiliation(s)
- Kai Deng
- US Department of Energy Joint BioEnergy Institute , Emeryville, CA , USA ; Sandia National Laboratories , Livermore, CA , USA
| | - Taichi E Takasuka
- US Department of Energy Great Lakes Bioenergy Research Center , Madison, WI , USA
| | - Christopher M Bianchetti
- US Department of Energy Great Lakes Bioenergy Research Center , Madison, WI , USA ; Department of Chemistry, University of Wisconsin-Oshkosh , Oshkosh, WI , USA
| | - Lai F Bergeman
- US Department of Energy Great Lakes Bioenergy Research Center , Madison, WI , USA
| | - Paul D Adams
- US Department of Energy Joint BioEnergy Institute , Emeryville, CA , USA ; Lawrence Berkeley National Laboratory , Berkeley, CA , USA ; Department of Bioengineering, University of California Berkeley , Berkeley, CA , USA
| | - Trent R Northen
- US Department of Energy Joint BioEnergy Institute , Emeryville, CA , USA ; Lawrence Berkeley National Laboratory , Berkeley, CA , USA
| | - Brian G Fox
- US Department of Energy Great Lakes Bioenergy Research Center , Madison, WI , USA ; Department of Biochemistry, University of Wisconsin-Madison , Madison, WI , USA
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Thompson RA, Layton DS, Guss AM, Olson DG, Lynd LR, Trinh CT. Elucidating central metabolic redox obstacles hindering ethanol production in Clostridium thermocellum. Metab Eng 2015; 32:207-219. [PMID: 26497628 DOI: 10.1016/j.ymben.2015.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 10/08/2015] [Accepted: 10/12/2015] [Indexed: 01/24/2023]
Abstract
Clostridium thermocellum is an anaerobic, Gram-positive, thermophilic bacterium that has generated great interest due to its ability to ferment lignocellulosic biomass to ethanol. However, ethanol production is low due to the complex and poorly understood branched metabolism of C. thermocellum, and in some cases overflow metabolism as well. In this work, we developed a predictive stoichiometric metabolic model for C. thermocellum which incorporates the current state of understanding, with particular attention to cofactor specificity in the atypical glycolytic enzymes and the complex energy, redox, and fermentative pathways with the goal of aiding metabolic engineering efforts. We validated the model's capability to encompass experimentally observed phenotypes for the parent strain and derived mutants designed for significant perturbation of redox and energy pathways. Metabolic flux distributions revealed significant alterations in key metabolic branch points (e.g., phosphoenol pyruvate, pyruvate, acetyl-CoA, and cofactor nodes) in engineered strains for channeling electron and carbon fluxes for enhanced ethanol synthesis, with the best performing strain doubling ethanol yield and titer compared to the parent strain. In silico predictions of a redox-imbalanced genotype incapable of growth were confirmed in vivo, and a mutant strain was used as a platform to probe redox bottlenecks in the central metabolism that hinder efficient ethanol production. The results highlight the robustness of the redox metabolism of C. thermocellum and the necessity of streamlined electron flux from reduced ferredoxin to NAD(P)H for high ethanol production. The model was further used to design a metabolic engineering strategy to phenotypically constrain C. thermocellum to achieve high ethanol yields while requiring minimal genetic manipulations. The model can be applied to design C. thermocellum as a platform microbe for consolidated bioprocessing to produce ethanol and other reduced metabolites.
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Affiliation(s)
- R Adam Thompson
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville and Oak Ridge National Laboratory, Oak Ridge, TN, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Donovan S Layton
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA
| | - Adam M Guss
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville and Oak Ridge National Laboratory, Oak Ridge, TN, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Biosciecnes Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Daniel G Olson
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Lee R Lynd
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Cong T Trinh
- Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville and Oak Ridge National Laboratory, Oak Ridge, TN, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN, USA.
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Nakonieczna A, Cooper CJ, Gryko R. Bacteriophages and bacteriophage-derived endolysins as potential therapeutics to combat Gram-positive spore forming bacteria. J Appl Microbiol 2015; 119:620-31. [PMID: 26109320 DOI: 10.1111/jam.12881] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 05/28/2015] [Accepted: 06/11/2015] [Indexed: 01/21/2023]
Abstract
Since their discovery in 1915, bacteriophages have been routinely used within Eastern Europe to treat a variety of bacterial infections. Although initially ignored by the West due to the success of antibiotics, increasing levels and diversity of antibiotic resistance is driving a renaissance for bacteriophage-derived therapy, which is in part due to the highly specific nature of bacteriophages as well as their relative abundance. This review focuses on the bacteriophages and derived lysins of relevant Gram-positive spore formers within the Bacillus cereus group and Clostridium genus that could have applications within the medical, food and environmental sectors.
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Affiliation(s)
- A Nakonieczna
- Biological Threats Identification and Countermeasure Center of the Military Institute of Hygiene and Epidemiology, Pulawy, Poland
| | - C J Cooper
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - R Gryko
- Biological Threats Identification and Countermeasure Center of the Military Institute of Hygiene and Epidemiology, Pulawy, Poland
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Currie DH, Raman B, Gowen CM, Tschaplinski TJ, Land ML, Brown SD, Covalla SF, Klingeman DM, Yang ZK, Engle NL, Johnson CM, Rodriguez M, Shaw AJ, Kenealy WR, Lynd LR, Fong SS, Mielenz JR, Davison BH, Hogsett DA, Herring CD. Genome-scale resources for Thermoanaerobacterium saccharolyticum. BMC SYSTEMS BIOLOGY 2015; 9:30. [PMID: 26111937 PMCID: PMC4518999 DOI: 10.1186/s12918-015-0159-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/09/2015] [Indexed: 01/12/2023]
Abstract
Background Thermoanaerobacterium saccharolyticum is a hemicellulose-degrading thermophilic anaerobe that was previously engineered to produce ethanol at high yield. A major project was undertaken to develop this organism into an industrial biocatalyst, but the lack of genome information and resources were recognized early on as a key limitation. Results Here we present a set of genome-scale resources to enable the systems level investigation and development of this potentially important industrial organism. Resources include a complete genome sequence for strain JW/SL-YS485, a genome-scale reconstruction of metabolism, tiled microarray data showing transcription units, mRNA expression data from 71 different growth conditions or timepoints and GC/MS-based metabolite analysis data from 42 different conditions or timepoints. Growth conditions include hemicellulose hydrolysate, the inhibitors HMF, furfural, diamide, and ethanol, as well as high levels of cellulose, xylose, cellobiose or maltodextrin. The genome consists of a 2.7 Mbp chromosome and a 110 Kbp megaplasmid. An active prophage was also detected, and the expression levels of CRISPR genes were observed to increase in association with those of the phage. Hemicellulose hydrolysate elicited a response of carbohydrate transport and catabolism genes, as well as poorly characterized genes suggesting a redox challenge. In some conditions, a time series of combined transcription and metabolite measurements were made to allow careful study of microbial physiology under process conditions. As a demonstration of the potential utility of the metabolic reconstruction, the OptKnock algorithm was used to predict a set of gene knockouts that maximize growth-coupled ethanol production. The predictions validated intuitive strain designs and matched previous experimental results. Conclusion These data will be a useful asset for efforts to develop T. saccharolyticum for efficient industrial production of biofuels. The resources presented herein may also be useful on a comparative basis for development of other lignocellulose degrading microbes, such as Clostridium thermocellum. Electronic supplementary material The online version of this article (doi:10.1186/s12918-015-0159-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Devin H Currie
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA.
| | - Babu Raman
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA. .,Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN, 46268, USA.
| | - Christopher M Gowen
- Chemical and Life Science Engineering, Virginia Commonwealth University, P.O. Box 843028, Richmond, Virginia, 23284, USA. .,Centre for Applied Bioscience and Bioengineering, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada.
| | - Timothy J Tschaplinski
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Miriam L Land
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Steven D Brown
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Sean F Covalla
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA.
| | - Dawn M Klingeman
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Zamin K Yang
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Nancy L Engle
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Courtney M Johnson
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Miguel Rodriguez
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - A Joe Shaw
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA. .,Novogy Inc, Cambridge, MA, 02138, USA.
| | | | - Lee R Lynd
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA. .,Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.
| | - Stephen S Fong
- Chemical and Life Science Engineering, Virginia Commonwealth University, P.O. Box 843028, Richmond, Virginia, 23284, USA.
| | - Jonathan R Mielenz
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | - Brian H Davison
- BioEnergy Science Center, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831, USA.
| | | | - Christopher D Herring
- Mascoma Corporation, 67 Etna Rd, 03766, Lebanon, NH, USA. .,Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.
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Gene knockout identification using an extension of Bees Hill Flux Balance Analysis. BIOMED RESEARCH INTERNATIONAL 2015; 2015:124537. [PMID: 25874200 PMCID: PMC4385639 DOI: 10.1155/2015/124537] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/22/2014] [Accepted: 10/31/2014] [Indexed: 01/01/2023]
Abstract
Microbial strain optimisation for the overproduction of a desired phenotype has been a popular topic in recent years. Gene knockout is a genetic engineering technique that can modify the metabolism of microbial cells to obtain desirable phenotypes. Optimisation algorithms have been developed to identify the effects of gene knockout. However, the complexities of metabolic networks have made the process of identifying the effects of genetic modification on desirable phenotypes challenging. Furthermore, a vast number of reactions in cellular metabolism often lead to a combinatorial problem in obtaining optimal gene knockout. The computational time increases exponentially as the size of the problem increases. This work reports an extension of Bees Hill Flux Balance Analysis (BHFBA) to identify optimal gene knockouts to maximise the production yield of desired phenotypes while sustaining the growth rate. This proposed method functions by integrating OptKnock into BHFBA for validating the results automatically. The results show that the extension of BHFBA is suitable, reliable, and applicable in predicting gene knockout. Through several experiments conducted on Escherichia coli, Bacillus subtilis, and Clostridium thermocellum as model organisms, extension of BHFBA has shown better performance in terms of computational time, stability, growth rate, and production yield of desired phenotypes.
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Daniell J, Nagaraju S, Burton F, Köpke M, Simpson SD. Low-Carbon Fuel and Chemical Production by Anaerobic Gas Fermentation. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015; 156:293-321. [PMID: 26957126 DOI: 10.1007/10_2015_5005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
World energy demand is expected to increase by up to 40% by 2035. Over this period, the global population is also expected to increase by a billion people. A challenge facing the global community is not only to increase the supply of fuel, but also to minimize fossil carbon emissions to safeguard the environment, at the same time as ensuring that food production and supply is not detrimentally impacted. Gas fermentation is a rapidly maturing technology which allows low carbon fuel and commodity chemical synthesis. Unlike traditional biofuel technologies, gas fermentation avoids the use of sugars, relying instead on gas streams rich in carbon monoxide and/or hydrogen and carbon dioxide as sources of carbon and energy for product synthesis by specialized bacteria collectively known as acetogens. Thus, gas fermentation enables access to a diverse array of novel, large volume, and globally available feedstocks including industrial waste gases and syngas produced, for example, via the gasification of municipal waste and biomass. Through the efforts of academic labs and early stage ventures, process scale-up challenges have been surmounted through the development of specialized bioreactors. Furthermore, tools for the genetic improvement of the acetogenic bacteria have been reported, paving the way for the production of a spectrum of ever-more valuable products via this process. As a result of these developments, interest in gas fermentation among both researchers and legislators has grown significantly in the past 5 years to the point that this approach is now considered amongst the mainstream of emerging technology solutions for near-term low-carbon fuel and chemical synthesis.
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Affiliation(s)
- James Daniell
- LanzaTech Inc., 8045 Lamon Ave, Suite 400, Skokie, IL, 60077, USA.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Shilpa Nagaraju
- LanzaTech Inc., 8045 Lamon Ave, Suite 400, Skokie, IL, 60077, USA
| | - Freya Burton
- LanzaTech Inc., 8045 Lamon Ave, Suite 400, Skokie, IL, 60077, USA
| | - Michael Köpke
- LanzaTech Inc., 8045 Lamon Ave, Suite 400, Skokie, IL, 60077, USA
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39
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Recent Advances in Second Generation Ethanol Production by Thermophilic Bacteria. ENERGIES 2014. [DOI: 10.3390/en8010001] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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40
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Senger RS, Yen JY, Fong SS. A review of genome-scale metabolic flux modeling of anaerobiosis in biotechnology. Curr Opin Chem Eng 2014. [DOI: 10.1016/j.coche.2014.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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41
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Henson MA, Hanly TJ. Dynamic flux balance analysis for synthetic microbial communities. IET Syst Biol 2014; 8:214-29. [PMID: 25257022 PMCID: PMC8687154 DOI: 10.1049/iet-syb.2013.0021] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 01/14/2023] Open
Abstract
Dynamic flux balance analysis (DFBA) is an extension of classical flux balance analysis that allows the dynamic effects of the extracellular environment on microbial metabolism to be predicted and optimised. Recently this computational framework has been extended to microbial communities for which the individual species are known and genome-scale metabolic reconstructions are available. In this review, the authors provide an overview of the emerging DFBA approach with a focus on two case studies involving the conversion of mixed hexose/pentose sugar mixtures by synthetic microbial co-culture systems. These case studies illustrate the key requirements of the DFBA approach, including the incorporation of individual species metabolic reconstructions, formulation of extracellular mass balances, identification of substrate uptake kinetics, numerical solution of the coupled linear program/differential equations and model adaptation for common, suboptimal growth conditions and identified species interactions. The review concludes with a summary of progress to date and possible directions for future research.
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Affiliation(s)
- Michael A Henson
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01007, USA.
| | - Timothy J Hanly
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01007, USA
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42
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Akinosho H, Yee K, Close D, Ragauskas A. The emergence of Clostridium thermocellum as a high utility candidate for consolidated bioprocessing applications. Front Chem 2014; 2:66. [PMID: 25207268 PMCID: PMC4143619 DOI: 10.3389/fchem.2014.00066] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/28/2014] [Indexed: 01/25/2023] Open
Abstract
First isolated in 1926, Clostridium thermocellum has recently received increased attention as a high utility candidate for use in consolidated bioprocessing (CBP) applications. These applications, which seek to process lignocellulosic biomass directly into useful products such as ethanol, are gaining traction as economically feasible routes toward the production of fuel and other high value chemical compounds as the shortcomings of fossil fuels become evident. This review evaluates C. thermocellum's role in this transitory process by highlighting recent discoveries relating to its genomic, transcriptomic, proteomic, and metabolomic responses to varying biomass sources, with a special emphasis placed on providing an overview of its unique, multivariate enzyme cellulosome complex and the role that this structure performs during biomass degradation. Both naturally evolved and genetically engineered strains are examined in light of their unique attributes and responses to various biomass treatment conditions, and the genetic tools that have been employed for their creation are presented. Several future routes for potential industrial usage are presented, and it is concluded that, although there have been many advances to significantly improve C. thermocellum's amenability to industrial use, several hurdles still remain to be overcome as this unique organism enjoys increased attention within the scientific community.
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Affiliation(s)
- Hannah Akinosho
- School of Chemistry and Biochemistry, Institute of Paper Science and Technology, Georgia Institute of Technology Atlanta, GA, USA ; Oak Ridge National Laboratory, BioEnergy Science Center Oak Ridge, TN, USA
| | - Kelsey Yee
- Oak Ridge National Laboratory, BioEnergy Science Center Oak Ridge, TN, USA ; Biosciences Division, Oak Ridge National Laboratory Oak Ridge, TN, USA
| | - Dan Close
- Biosciences Division, Oak Ridge National Laboratory Oak Ridge, TN, USA
| | - Arthur Ragauskas
- Oak Ridge National Laboratory, BioEnergy Science Center Oak Ridge, TN, USA ; Department of Chemical and Biomolecular Engineering and Department of Forestry, Wildlife, and Fisheries, University of Tennessee Knoxville, TN, USA
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Vanee N, Brooks JP, Spicer V, Shamshurin D, Krokhin O, Wilkins JA, Deng Y, Fong SS. Proteomics-based metabolic modeling and characterization of the cellulolytic bacterium Thermobifida fusca. BMC SYSTEMS BIOLOGY 2014; 8:86. [PMID: 25115351 PMCID: PMC4236713 DOI: 10.1186/s12918-014-0086-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 07/14/2014] [Indexed: 12/31/2022]
Abstract
Background Thermobifida fusca is a cellulolytic bacterium with potential to be used as a platform organism for sustainable industrial production of biofuels, pharmaceutical ingredients and other bioprocesses due to its capability of potential to convert plant biomass to value-added chemicals. To best develop T. fusca as a bioprocess organism, it is important to understand its native cellular processes. In the current study, we characterize the metabolic network of T. fusca through reconstruction of a genome-scale metabolic model and proteomics data. The overall goal of this study was to use multiple metabolic models generated by different methods and comparison to experimental data to gain a high-confidence understanding of the T. fusca metabolic network. Results We report the generation of three versions of a metabolic model of Thermobifida fusca sp. XY developed using three different approaches (automated, semi-automated, and proteomics-derived). The model closest to in vivo growth was the proteomics-derived model that consists of 975 reactions involving 1382 metabolites and account for 316 EC numbers (296 genes). The model was optimized for biomass production with the optimal flux of 0.48 doublings per hour when grown on cellobiose with a substrate uptake rate of 0.25 mmole/h. In vivo activity of the DXP pathway for terpenoid biosynthesis was also confirmed using real-time PCR. Conclusions iTfu296 provides a platform to understand and explore the metabolic capabilities of the actinomycete T. fusca for the potential use in bioprocess industries for the production of biofuel and pharmaceutical ingredients. By comparing different model reconstruction methods, the use of high-throughput proteomics data as a starting point proved to be the most accurate to in vivo growth.
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Fong SS. Computational approaches to metabolic engineering utilizing systems biology and synthetic biology. Comput Struct Biotechnol J 2014; 11:28-34. [PMID: 25379141 PMCID: PMC4212286 DOI: 10.1016/j.csbj.2014.08.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Metabolic engineering modifies cellular function to address various biochemical applications. Underlying metabolic engineering efforts are a host of tools and knowledge that are integrated to enable successful outcomes. Concurrent development of computational and experimental tools has enabled different approaches to metabolic engineering. One approach is to leverage knowledge and computational tools to prospectively predict designs to achieve the desired outcome. An alternative approach is to utilize combinatorial experimental tools to empirically explore the range of cellular function and to screen for desired traits. This mini-review focuses on computational systems biology and synthetic biology tools that can be used in combination for prospective in silico strain design.
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Affiliation(s)
- Stephen S. Fong
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, 601 W. Main St., Richmond, VA 23284, United States
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Choon YW, Mohamad MS, Deris S, Illias RM, Chong CK, Chai LE, Omatu S, Corchado JM. Differential Bees Flux Balance Analysis with OptKnock for in silico microbial strains optimization. PLoS One 2014; 9:e102744. [PMID: 25047076 PMCID: PMC4105462 DOI: 10.1371/journal.pone.0102744] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 06/23/2014] [Indexed: 01/16/2023] Open
Abstract
Microbial strains optimization for the overproduction of desired phenotype has been a popular topic in recent years. The strains can be optimized through several techniques in the field of genetic engineering. Gene knockout is a genetic engineering technique that can engineer the metabolism of microbial cells with the objective to obtain desirable phenotypes. However, the complexities of the metabolic networks have made the process to identify the effects of genetic modification on the desirable phenotypes challenging. Furthermore, a vast number of reactions in cellular metabolism often lead to the combinatorial problem in obtaining optimal gene deletion strategy. Basically, the size of a genome-scale metabolic model is usually large. As the size of the problem increases, the computation time increases exponentially. In this paper, we propose Differential Bees Flux Balance Analysis (DBFBA) with OptKnock to identify optimal gene knockout strategies for maximizing the production yield of desired phenotypes while sustaining the growth rate. This proposed method functions by improving the performance of a hybrid of Bees Algorithm and Flux Balance Analysis (BAFBA) by hybridizing Differential Evolution (DE) algorithm into neighborhood searching strategy of BAFBA. In addition, DBFBA is integrated with OptKnock to validate the results for improving the reliability the work. Through several experiments conducted on Escherichia coli, Bacillus subtilis, and Clostridium thermocellum as the model organisms, DBFBA has shown a better performance in terms of computational time, stability, growth rate, and production yield of desired phenotypes compared to the methods used in previous works.
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Affiliation(s)
- Yee Wen Choon
- Artificial Intelligence and Bioinformatics Group, Faculty of Computing, Universiti Teknologi Malaysia, Johor, Malaysia
| | - Mohd Saberi Mohamad
- Artificial Intelligence and Bioinformatics Group, Faculty of Computing, Universiti Teknologi Malaysia, Johor, Malaysia
- * E-mail:
| | - Safaai Deris
- Artificial Intelligence and Bioinformatics Group, Faculty of Computing, Universiti Teknologi Malaysia, Johor, Malaysia
| | - Rosli Md. Illias
- Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Chuii Khim Chong
- Artificial Intelligence and Bioinformatics Group, Faculty of Computing, Universiti Teknologi Malaysia, Johor, Malaysia
| | - Lian En Chai
- Artificial Intelligence and Bioinformatics Group, Faculty of Computing, Universiti Teknologi Malaysia, Johor, Malaysia
| | - Sigeru Omatu
- Department of Electronics, Information and Communication Engineering, Osaka Institute of Technology, Osaka, Japan
| | - Juan Manuel Corchado
- Biomedical Research Institute of Salamanca/BISITE Research Group, University of Salamanca, Salamanca, Spain
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46
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Blumer-Schuette SE, Brown SD, Sander KB, Bayer EA, Kataeva I, Zurawski JV, Conway JM, Adams MWW, Kelly RM. Thermophilic lignocellulose deconstruction. FEMS Microbiol Rev 2014; 38:393-448. [DOI: 10.1111/1574-6976.12044] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 08/20/2013] [Accepted: 08/28/2013] [Indexed: 11/28/2022] Open
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Yee KL, Rodriguez Jr M, Thompson OA, Fu C, Wang ZY, Davison BH, Mielenz JR. Consolidated bioprocessing of transgenic switchgrass by an engineered and evolved Clostridium thermocellum strain. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:75. [PMID: 24876889 PMCID: PMC4037551 DOI: 10.1186/1754-6834-7-75] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 05/08/2014] [Indexed: 05/04/2023]
Abstract
BACKGROUND Switchgrass is an abundant and dedicated bioenergy feedstock, however its inherent recalcitrance is one of the economic hurdles for producing biofuels. The downregulation of the caffeic acid O-methyl transferase (COMT) gene in the lignin pathway of switchgrass reduced lignin content and S/G ratio, and the transgenic lines showed improved fermentation yield with Saccharomyces cerevisiae and wild-type Clostridium thermocellum (ATCC 27405) in comparison to the wild-type switchgrass. RESULTS Here we examine the conversion and yield of the COMT transgenic and wild-type switchgrass lines with an engineered and evolved C. thermocellum (M1570) strain. The fermentation of the transgenic switchgrass by M1570 had superior conversion relative to the wild-type control switchgrass line with an increase in conversion of approximately 20% and ethanol being the primary product accounting for 90% of the total metabolites measured by HPLC analysis. CONCLUSIONS The engineered and evolved C. thermocellum M1570 was found to respond to the apparent reduced recalcitrance of the COMT switchgrass with no substrate inhibition, producing more ethanol on the transgenic feedstock than the wild-type substrate. Since ethanol was the main fermentation metabolite produced by an engineered and evolved C. thermocellum strain, its ethanol yield on a transgenic switchgrass substrate (gram/gram (g/g) glucan liberated) is the highest produced thus far. This result indicates that the advantages of a modified feedstock can be combined with a modified consolidated bioprocessing microorganism as anticipated.
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Affiliation(s)
- Kelsey L Yee
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6341, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6037, USA
| | - Miguel Rodriguez Jr
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6341, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6037, USA
| | - Olivia A Thompson
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6341, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6037, USA
| | - Chunxiang Fu
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
- Current address: Qingdao Institute of Bioenergy and Bioprocess Technology, CAS, No.189 Songling Rd, Qingdao City, Shandong Province 266101, People’s Republic of China
| | - Zeng-Yu Wang
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6037, USA
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Brian H Davison
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6341, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6037, USA
| | - Jonathan R Mielenz
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6341, USA
- BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6037, USA
- White Cliff Biosystems, Rockwood, TN 37854, USA
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Nagarajan H, Sahin M, Nogales J, Latif H, Lovley DR, Ebrahim A, Zengler K. Characterizing acetogenic metabolism using a genome-scale metabolic reconstruction of Clostridium ljungdahlii. Microb Cell Fact 2013; 12:118. [PMID: 24274140 PMCID: PMC4222884 DOI: 10.1186/1475-2859-12-118] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 11/21/2013] [Indexed: 11/17/2022] Open
Abstract
Background The metabolic capabilities of acetogens to ferment a wide range of sugars, to grow autotrophically on H2/CO2, and more importantly on synthesis gas (H2/CO/CO2) make them very attractive candidates as production hosts for biofuels and biocommodities. Acetogenic metabolism is considered one of the earliest modes of bacterial metabolism. A thorough understanding of various factors governing the metabolism, in particular energy conservation mechanisms, is critical for metabolic engineering of acetogens for targeted production of desired chemicals. Results Here, we present the genome-scale metabolic network of Clostridium ljungdahlii, the first such model for an acetogen. This genome-scale model (iHN637) consisting of 637 genes, 785 reactions, and 698 metabolites captures all the major central metabolic and biosynthetic pathways, in particular pathways involved in carbon fixation and energy conservation. A combination of metabolic modeling, with physiological and transcriptomic data provided insights into autotrophic metabolism as well as aided the characterization of a nitrate reduction pathway in C. ljungdahlii. Analysis of the iHN637 metabolic model revealed that flavin based electron bifurcation played a key role in energy conservation during autotrophic growth and helped identify genes for some of the critical steps in this mechanism. Conclusions iHN637 represents a predictive model that recapitulates experimental data, and provides valuable insights into the metabolic response of C. ljungdahlii to genetic perturbations under various growth conditions. Thus, the model will be instrumental in guiding metabolic engineering of C. ljungdahlii for the industrial production of biocommodities and biofuels.
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Affiliation(s)
- Harish Nagarajan
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
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Lin L, Xu J. Dissecting and engineering metabolic and regulatory networks of thermophilic bacteria for biofuel production. Biotechnol Adv 2013; 31:827-37. [DOI: 10.1016/j.biotechadv.2013.03.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/06/2013] [Accepted: 03/10/2013] [Indexed: 01/08/2023]
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50
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Linville JL, Rodriguez M, Mielenz JR, Cox CD. Kinetic modeling of batch fermentation for Populus hydrolysate tolerant mutant and wild type strains of Clostridium thermocellum. BIORESOURCE TECHNOLOGY 2013; 147:605-613. [PMID: 24036527 DOI: 10.1016/j.biortech.2013.08.086] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/12/2013] [Accepted: 08/13/2013] [Indexed: 05/04/2023]
Abstract
The extent of inhibition of two strains of Clostridium thermocellum by a Populus hydrolysate was investigated. A Monod-based model of wild type (WT) and Populus hydrolysate tolerant mutant (PM) strains of the cellulolytic bacterium C. thermocellum was developed to quantify growth kinetics in standard media and the extent of inhibition to a Populus hydrolysate. The PM was characterized by a higher growth rate (μmax=1.223 vs. 0.571 h(-1)) and less inhibition (KI,gen=0.991 vs. 0.757) in 10% v/v Populus hydrolysate compared to the WT. In 17.5% v/v Populus hydrolysate inhibition of PM increased slightly (KI,gen=0.888), whereas the WT was strongly inhibited and did not grow in a reproducible manner. Of the individual inhibitors tested, 4-hydroxybenzoic acid was the most inhibitory, followed by galacturonic acid. The PM did not have a greater ability to detoxify the hydrolysate than the WT.
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Affiliation(s)
- Jessica L Linville
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, United States; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Miguel Rodriguez
- Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, United States; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Jonathan R Mielenz
- Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, United States; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Chris D Cox
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, United States; Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, United States; Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, United States.
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