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Bordel S, Rodríguez Y, Hakobyan A, Rodríguez E, Lebrero R, Muñoz R. Genome scale metabolic modeling reveals the metabolic potential of three Type II methanotrophs of the genus Methylocystis. Metab Eng 2019; 54:191-199. [DOI: 10.1016/j.ymben.2019.04.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 12/19/2022]
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52
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Datta A, Hossain A, Roy S. An Overview on Biofuels and Their Advantages and Disadvantages. ACTA ACUST UNITED AC 2019. [DOI: 10.14233/ajchem.2019.22098] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Blazing of fossil energy resources generally changes the global climate. Speeding up of global temperate nowadays is an important aspect. Emission of greenhouse gases mainly from blazing of fossil energy resources is one of the most important sources. So, to carry the significant energy and to reduce air pollution, biofuels might be a substitute energy sources. The unnecessary utilization of fossil energy resources or fuels results deficient in the storage in underground earth then people naturally have to depend on biofuels. Consequently increasing demand for the manufacture of biofuels will put a huge burden on agriculture and food prices. Biofuels generally attributed as liquid fuels which are made from the biomass. This consists of mostly wood, vegetable oils, forestry products, agricultural crops, agricultural residues or municipal garbage, residues of domestic animal wastes and aquatic plants. In this review, we summarized the different types of biofuels including biodiesel and their comparative study, production and uses from an ecological perspective.
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Affiliation(s)
- Arup Datta
- Department of Chemistry, Shibpur Dinobundhoo Institution (College), 412/1, G.T. Road (South), Howrah-711102, India
| | - Aslam Hossain
- Department of Physical and Inorganic Chemistry, Institute of Natural Sciences and Mathematics, Ural Federal University, 620000, Yekaterinburg, Russia
| | - Sanjay Roy
- Department of Chemistry, Shibpur Dinobundhoo Institution (College), 412/1, G.T. Road (South), Howrah-711102, India
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53
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Nguyen LT, Lee EY. Biological conversion of methane to putrescine using genome-scale model-guided metabolic engineering of a methanotrophic bacterium Methylomicrobium alcaliphilum 20Z. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:147. [PMID: 31223337 PMCID: PMC6570963 DOI: 10.1186/s13068-019-1490-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/07/2019] [Indexed: 05/24/2023]
Abstract
BACKGROUND Methane is the primary component of natural gas and biogas. The huge abundance of methane makes it a promising alternative carbon source for industrial biotechnology. Herein, we report diamine compound, putrescine, production from methane by an industrially promising methanotroph Methylomicrobium alcaliphilum 20Z. RESULTS We conducted adaptive evolution to improve putrescine tolerance of M. alcaliphilum 20Z because putrescine highly inhibits the cell growth. The evolved strain 20ZE was able to grow in the presence of 400 mM of putrescine dihydrochloride. The expression of linear pathway ornithine decarboxylase genes from Escherichia coli and Methylosinus trichosporium OB3b allowed the engineered strain to produce putrescine. A higher putrescine titer of 12.44 mg/L was obtained in the strain 20ZE-pACO with ornithine decarboxylase from M. trichosporium OB3b. For elimination of the putrescine utilization pathway, spermidine synthase (MEALZ_3408) was knocked out, resulting in no spermidine formation in the strain 20ZES1-pACO with a putrescine titer of 18.43 mg/L. Next, a genome-scale metabolic model was applied to identify gene knockout strategies. Acetate kinase (MEALZ_2853) and subsequently lactate dehydrogenase (MEALZ_0534) were selected as knockout targets, and the deletion of these genes resulted in an improvement of the putrescine titer to 26.69 mg/L. Furthermore, the putrescine titer was improved to 39.04 mg/L by overexpression of key genes in the ornithine biosynthesis pathway under control of the pTac promoter. Finally, suitable nitrogen sources for growth of M. alcaliphilum 20Z and putrescine production were optimized with the supplement of 2 mM ammonium chloride to nitrate mineral salt medium, and this led to the production of 98.08 mg/L putrescine, almost eightfold higher than that from the initial strain. Transcriptome analysis of the engineered strains showed upregulation of most genes involved in methane assimilation, citric acid cycle, and ammonia assimilation in ammonia nitrate mineral salt medium, compared to nitrate mineral salt medium. CONCLUSIONS The engineered M. alcaliphilum 20ZE4-pACO strain was able to produce putrescine up to 98.08 mg/L, almost eightfold higher than the initial strain. This study represents the bioconversion of methane to putrescine-a high value-added diamine compound.
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Affiliation(s)
- Linh Thanh Nguyen
- Department of Chemical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 17104 Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 17104 Republic of Korea
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54
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Development of a CRISPR/Cas9 System for Methylococcus capsulatus In Vivo Gene Editing. Appl Environ Microbiol 2019; 85:AEM.00340-19. [PMID: 30926729 PMCID: PMC6532038 DOI: 10.1128/aem.00340-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 03/22/2019] [Indexed: 12/26/2022] Open
Abstract
In this study, we targeted the development and evaluation of broad-host-range CRISPR/Cas9 gene-editing tools in order to enhance the genetic-engineering capabilities of an industrially relevant methanotrophic biocatalyst. The CRISPR/Cas9 system developed in this study expands the genetic tools available to define molecular mechanisms in methanotrophic bacteria and has the potential to foster advances in the generation of novel biocatalysts to produce biofuels, platform chemicals, and high-value products from natural gas- and biogas-derived methane. Further, due to the broad-host-range applicability, these genetic tools may also enable innovative approaches to overcome the barriers associated with genetically engineering diverse, industrially promising nonmodel microorganisms. Methanotrophic bacteria play a crucial role in the Earth’s biogeochemical cycle and have the potential to be employed in industrial biomanufacturing processes due to their capacity to use natural gas- and biogas-derived methane as a sole carbon and energy source. Advanced gene-editing systems have the potential to enable rapid, high-throughput methanotrophic genetics and biocatalyst development. To this end, we employed a series of broad-host-range expression plasmids to construct a conjugatable clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene-editing system in Methylococcus capsulatus (Bath). Heterologous coexpression of the Streptococcus pyogenes Cas9 endonuclease and a synthetic single guide RNA (gRNA) showed efficient Cas9 DNA targeting and double-stranded DNA (dsDNA) cleavage that resulted in cell death. We demonstrated effective in vivo editing of plasmid DNA using both Cas9 and Cas9D10A nickase to convert green fluorescent protein (GFP)- to blue fluorescent protein (BFP)-expressing cells with 71% efficiency. Further, we successfully introduced a premature stop codon into the soluble methane monooxygenase (sMMO) hydroxylase component-encoding mmoX gene with the Cas9D10A nickase, disrupting sMMO function. These data provide proof of concept for CRISPR/Cas9-mediated gene editing in M. capsulatus. Given the broad-host-range replicons and conjugation capability of these CRISPR/Cas9 tools, they have potential utility in other methanotrophs and a wide array of Gram-negative microorganisms. IMPORTANCE In this study, we targeted the development and evaluation of broad-host-range CRISPR/Cas9 gene-editing tools in order to enhance the genetic-engineering capabilities of an industrially relevant methanotrophic biocatalyst. The CRISPR/Cas9 system developed in this study expands the genetic tools available to define molecular mechanisms in methanotrophic bacteria and has the potential to foster advances in the generation of novel biocatalysts to produce biofuels, platform chemicals, and high-value products from natural gas- and biogas-derived methane. Further, due to the broad-host-range applicability, these genetic tools may also enable innovative approaches to overcome the barriers associated with genetically engineering diverse, industrially promising nonmodel microorganisms.
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55
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Two Experimental Protocols for Accurate Measurement of Gas Component Uptake and Production Rates in Bioconversion Processes. Sci Rep 2019; 9:5899. [PMID: 30976062 PMCID: PMC6459910 DOI: 10.1038/s41598-019-42469-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 04/02/2019] [Indexed: 12/04/2022] Open
Abstract
Bioconversion processes offer many economic, environmental, and societal advantages for production of fuels and chemicals. Successful commercialization of any biotechnology usually requires accurate characterization of cell growth dynamics, substrate conversion and production excretion rates. Despite recent advancements in analytical equipment, obtaining accurate measurement of gas component uptake or production rates remains challenging due to their high sensitivity to system pressure or volume changes. Specifically, the consumption and production of various gases will result in changes in system pressure (for batch operations) or off-gas flow rate (for continuous operations). These changes would cause significant errors in the estimated gas component uptake and production rates if they were not accounted for. In this work, we propose two easy-to-implement experimental protocols and associated calculation procedures to obtain accurate measurements of gas component consumption and production rates; one is for batch operation and one is for continuous operation. For depressurized (i.e., system pressure below 1 atm) batch cultures, nitrogen (or other inert gases) is used to repressurize the system to 1 atm before taking sample; while for continuous cultures, He (or other inert gases) is used as an internal tracer to accurately measure off-gas flow rate. The effectiveness and accuracy of the two protocols and associated calculation procedures are demonstrated using several case studies with both abiotic and biotic systems.
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56
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Core Metabolism Shifts during Growth on Methanol versus Methane in the Methanotroph Methylomicrobium buryatense 5GB1. mBio 2019; 10:mBio.00406-19. [PMID: 30967465 PMCID: PMC6456754 DOI: 10.1128/mbio.00406-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One-carbon compounds such as methane and methanol are of increasing interest as sustainable substrates for biological production of fuels and industrial chemicals. The bacteria that carry out these conversions have been studied for many decades, but gaps exist in our knowledge of their metabolic pathways. One such gap is the difference between growth on methane and growth on methanol. Understanding such metabolism is important, since each has advantages and disadvantages as a feedstock for production of chemicals and fuels. The significance of our research is in the demonstration that the metabolic network is substantially altered in each case and in the delineation of these changes. The resulting new insights into the core metabolism of this bacterium now provide an improved basis for future strain design. Methylomicrobium buryatense 5GB1 is an obligate methylotroph which grows on methane or methanol with similar growth rates. It has long been assumed that the core metabolic pathways must be similar on the two substrates, but recent studies of methane metabolism in this bacterium suggest that growth on methanol might have significant differences from growth on methane. In this study, both a targeted metabolomics approach and a 13C tracer approach were taken to understand core carbon metabolism in M. buryatense 5GB1 during growth on methanol and to determine whether such differences occur. Our results suggest a systematic shift of active core metabolism in which increased flux occurred through both the Entner-Doudoroff (ED) pathway and the partial serine cycle, while the tricarboxylic acid (TCA) cycle was incomplete, in contrast to growth on methane. Using the experimental results as constraints, we applied flux balance analysis to determine the metabolic flux phenotype of M. buryatense 5GB1 growing on methanol, and the results are consistent with predictions based on ATP and NADH changes. Transcriptomics analysis suggested that the changes in fluxes and metabolite levels represented results of posttranscriptional regulation. The combination of flux balance analysis of the genome-scale model and the flux ratio from 13C data changed the solution space for a better prediction of cell behavior and demonstrated the significant differences in physiology between growth on methane and growth on methanol.
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57
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Henard CA, Franklin TG, Youhenna B, But S, Alexander D, Kalyuzhnaya MG, Guarnieri MT. Biogas Biocatalysis: Methanotrophic Bacterial Cultivation, Metabolite Profiling, and Bioconversion to Lactic Acid. Front Microbiol 2018; 9:2610. [PMID: 30429839 PMCID: PMC6220066 DOI: 10.3389/fmicb.2018.02610] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/12/2018] [Indexed: 12/19/2022] Open
Abstract
Anaerobic digestion (AD) of waste substrates, and renewable biomass and crop residues offers a means to generate energy-rich biogas. However, at present, AD-derived biogas is primarily flared or used for combined heat and power (CHP), in part due to inefficient gas-to-liquid conversion technologies. Methanotrophic bacteria are capable of utilizing methane as a sole carbon and energy source, offering promising potential for biological gas-to-liquid conversion of AD-derived biogas. Here, we report cultivation of three phylogenetically diverse methanotrophic bacteria on biogas streams derived from AD of a series of energy crop residues. Strains maintained comparable central metabolic activity and displayed minimal growth inhibition when cultivated under batch configuration on AD biogas streams relative to pure methane, although metabolite analysis suggested biogas streams increase cellular oxidative stress. In contrast to batch cultivation, growth arrest was observed under continuous cultivation configuration, concurrent with increased biosynthesis and excretion of lactate. We examined the potential for enhanced lactate production via the employ of a pyruvate dehydrogenase mutant strain, ultimately achieving 0.027 g lactate/g DCW/h, the highest reported lactate specific productivity from biogas to date.
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Affiliation(s)
- Calvin A Henard
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, United States
| | - Tyler G Franklin
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, United States
| | - Batool Youhenna
- Biology Department, San Diego State University, San Diego, CA, United States
| | - Sergey But
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Moscow, Russia
| | | | | | - Michael T Guarnieri
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO, United States
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58
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Kwon M, Ho A, Yoon S. Novel approaches and reasons to isolate methanotrophic bacteria with biotechnological potentials: recent achievements and perspectives. Appl Microbiol Biotechnol 2018; 103:1-8. [PMID: 30315351 DOI: 10.1007/s00253-018-9435-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 10/02/2018] [Accepted: 10/02/2018] [Indexed: 10/28/2022]
Abstract
The recent drop in the price of natural gas has rekindled the interests in methanotrophs, the organisms capable of utilizing methane as the sole electron donor and carbon source, as biocatalysts for various industrial applications. As heterologous expression of the methane monooxygenases in more amenable hosts has been proven to be nearly impossible, future success in methanotroph biotechnology largely depends on securing phylogenetically and phenotypically diverse methanotrophs with relatively high growth rates. For long, isolation of methanotrophs have relied on repeated single colony picking after initial batch enrichment with methane, which is a very rigorous and time-consuming process. In this review, three unconventional isolation methods devised for facilitation of the isolation process, diversification of targeted methanotrophs, and/or screening of rapid growers are summarized. The soil substrate membrane method allowed for isolation of previously elusive methanotrophs and application of high-throughput extinction plating technique facilitated the isolation procedure. Use of a chemostat with gradually increased dilution rates proved effective in screening for the fastest-growing methanotrophs from environmental samples. Development of new isolation technologies incorporating microfluidics and single-cell techniques may lead to discovery of previously unculturable methanotrophs with unexpected metabolic potentials and thus, certainly warrant future investigation.
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Affiliation(s)
- Miye Kwon
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea
| | - Adrian Ho
- Institute for Microbiology, Leibniz Universität Hannover, 30419, Hannover, Germany
| | - Sukhwan Yoon
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea.
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59
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Tays C, Guarnieri MT, Sauvageau D, Stein LY. Combined Effects of Carbon and Nitrogen Source to Optimize Growth of Proteobacterial Methanotrophs. Front Microbiol 2018; 9:2239. [PMID: 30319568 PMCID: PMC6167414 DOI: 10.3389/fmicb.2018.02239] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 09/03/2018] [Indexed: 11/13/2022] Open
Abstract
Methane, a potent greenhouse gas, and methanol, commonly called wood alcohol, are common by-products of modern industrial processes. They can, however, be consumed as a feedstock by bacteria known as methanotrophs, which can serve as useful vectors for biotransformation and bioproduction. Successful implementation in industrial settings relies upon efficient growth and bioconversion, and the optimization of culturing conditions for these bacteria remains an ongoing effort, complicated by the wide variety of characteristics present in the methanotroph culture collection. Here, we demonstrate the variable growth outcomes of five diverse methanotrophic strains – Methylocystis sp. Rockwell, Methylocystis sp. WRRC1, Methylosinus trichosporium OB3b, Methylomicrobium album BG8, and Methylomonas denitrificans FJG1 – grown on either methane or methanol, at three different concentrations, with either ammonium or nitrate provided as nitrogen source. Maximum optical density (OD), growth rate, and biomass yield were assessed for each condition. Further metabolite and fatty acid methyl ester (FAME) analyses were completed for Methylocystis sp. Rockwell and M. album BG8. The results indicate differential response to these growth conditions, with a general preference for ammonium-based growth over nitrate, except for M. denitrificans FJG1. Methane is also preferred by most strains, with methanol resulting in unreliable or inhibited growth in all but M. album BG8. Metabolite analysis points to monitoring of excreted formic acid as a potential indicator of adverse growth conditions, while the magnitude of FAME variation between conditions may point to strains with broader substrate tolerance. These findings suggest that methanotroph strains must be carefully evaluated before use in industry, both to identify optimal conditions and to ensure the strain selected is appropriate for the process of interest. Much work remains in addressing the optimization of growth strategies for these promising microorganisms since disregarding these important steps in process development could ultimately lead to inefficient or failed bioprocesses.
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Affiliation(s)
- Catherine Tays
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada
| | | | - Dominic Sauvageau
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada
| | - Lisa Y Stein
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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60
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Nazem-Bokaee H, Maranas CD. A Prospective Study on the Fermentation Landscape of Gaseous Substrates to Biorenewables Using Methanosarcina acetivorans Metabolic Model. Front Microbiol 2018; 9:1855. [PMID: 30197630 PMCID: PMC6117407 DOI: 10.3389/fmicb.2018.01855] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 07/24/2018] [Indexed: 12/18/2022] Open
Abstract
The abundance of methane in shale gas and of other gases such as carbon monoxide, hydrogen, and carbon dioxide as chemical process byproducts has motivated the use of gas fermentation for bioproduction. Recent advances in metabolic engineering and synthetic biology allow for engineering of microbes metabolizing a variety of chemicals including gaseous feeds into a number of biorenewables and transportation liquid fuels. New computational tools enable the systematic exploration of all feasible conversion alternatives. Here we computationally assessed all thermodynamically feasible ways of co-utilizing CH4, CO, and CO2 using ferric as terminal electron acceptor for the production of all key precursor metabolites. We identified the thermodynamically feasible co-utilization ratio ranges of CH4, CO, and CO2 toward production of the target metabolite(s) as a function of ferric uptake. A revised version of the iMAC868 genome-scale metabolic model of Methanosarcina acetivorans was chosen to assess co-utilization of CH4, CO, and CO2 and their conversion into selected target products using the optStoic pathway design tool. This revised version contains the latest information on electron flow mechanisms by the methanogen while supplied with methane as the sole carbon source. The interplay between different gas co-utilization ratios and the energetics of reverse methanogenesis were also analyzed using the same metabolic model.
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Affiliation(s)
- Hadi Nazem-Bokaee
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
| | - Costas D Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, United States
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61
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Lieven C, Herrgård MJ, Sonnenschein N. Microbial Methylotrophic Metabolism: Recent Metabolic Modeling Efforts and Their Applications In Industrial Biotechnology. Biotechnol J 2018; 13:e1800011. [PMID: 29917330 DOI: 10.1002/biot.201800011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/31/2018] [Indexed: 11/08/2022]
Abstract
Developing methylotrophic bacteria into cell factories that meet the chemical demand of the future could be both economical and environmentally friendly. Methane is not only an abundant, low-cost resource but also a potent greenhouse gas, the capture of which could help to reduce greenhouse gas emissions. Rational strain design workflows rely on the availability of carefully combined knowledge often in the form of genome-scale metabolic models to construct high-producer organisms. In this review, the authors present the most recent genome-scale metabolic models in aerobic methylotrophy and their applications. Further, the authors present models for the study of anaerobic methanotrophy through reverse methanogenesis and suggest organisms that may be of interest for expanding one-carbon industrial biotechnology. Metabolic models of methylotrophs are scarce, yet they are important first steps toward rational strain-design in these organisms.
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Affiliation(s)
- Christian Lieven
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Markus J Herrgård
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Nikolaus Sonnenschein
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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62
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Bioconversion of methane to C-4 carboxylic acids using carbon flux through acetyl-CoA in engineered Methylomicrobium buryatense 5GB1C. Metab Eng 2018; 48:175-183. [PMID: 29883803 DOI: 10.1016/j.ymben.2018.06.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 05/31/2018] [Accepted: 06/01/2018] [Indexed: 11/24/2022]
Abstract
Methane, the primary component of natural gas, is the second most abundant greenhouse gas (GHG) and contributes significantly to climate change. The conversion of methane to industrial platform chemicals provides an attractive opportunity to decrease GHG emissions and utilize this inexpensive and abundantly available gas as a carbon feedstock. While technologies exist for chemical conversion of methane to liquid fuels, the technical complexity of these processes mandate high capital expenditure, large-scale commercial facilities to leverage economies of scale that cannot be efficiently scaled down. Alternatively, bioconversion technologies capable of efficient small-scale operation with high carbon and energy efficiency can enable deployment at remote methane resources inaccessible to current chemical technologies. Aerobic obligate methanotrophs, specifically Methylomicrobium buryatense 5GB1, have recently garnered increased research interest for development of such bio-technologies. In this study, we demonstrate production of C-4 carboxylic acids non-native to the host, specifically crotonic and butyric acids, from methane in an engineered M. buryatense 5GB1C by diversion of carbon flux through the acetyl-CoA node of central 'sugar' linked metabolic pathways using reverse β-oxidation pathway genes. The synthesis of short chain carboxylic acids through the acetyl-CoA node demonstrates the potential for engineering M. buryatense 5GB1 as a platform for bioconversion of methane to a number of value added industrial chemicals, and presents new opportunities for further diversifying the products obtainable from methane as the feedstock.
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63
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Freed E, Fenster J, Smolinski SL, Walker J, Henard CA, Gill R, Eckert CA. Building a genome engineering toolbox in nonmodel prokaryotic microbes. Biotechnol Bioeng 2018; 115:2120-2138. [PMID: 29750332 DOI: 10.1002/bit.26727] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/02/2018] [Accepted: 03/10/2018] [Indexed: 12/26/2022]
Abstract
The realization of a sustainable bioeconomy requires our ability to understand and engineer complex design principles for the development of platform organisms capable of efficient conversion of cheap and sustainable feedstocks (e.g., sunlight, CO2 , and nonfood biomass) into biofuels and bioproducts at sufficient titers and costs. For model microbes, such as Escherichia coli, advances in DNA reading and writing technologies are driving the adoption of new paradigms for engineering biological systems. Unfortunately, microbes with properties of interest for the utilization of cheap and renewable feedstocks, such as photosynthesis, autotrophic growth, and cellulose degradation, have very few, if any, genetic tools for metabolic engineering. Therefore, it is important to develop "design rules" for building a genetic toolbox for novel microbes. Here, we present an overview of our current understanding of these rules for the genetic manipulation of prokaryotic microbes and the available genetic tools to expand our ability to genetically engineer nonmodel systems.
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Affiliation(s)
- Emily Freed
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO
| | - Jacob Fenster
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO.,Chemical and Biological Engineering, University of Colorado, Boulder, CO
| | | | - Julie Walker
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO
| | - Calvin A Henard
- National Renewable Energy Laboratory, National Bioenergy Center, Golden, CO
| | - Ryan Gill
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO.,Chemical and Biological Engineering, University of Colorado, Boulder, CO
| | - Carrie A Eckert
- National Renewable Energy Laboratory, Biosciences Center, Golden, CO.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO
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64
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Rapid isolation of fast-growing methanotrophs from environmental samples using continuous cultivation with gradually increased dilution rates. Appl Microbiol Biotechnol 2018; 102:5707-5715. [PMID: 29736819 DOI: 10.1007/s00253-018-8978-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/22/2018] [Accepted: 03/30/2018] [Indexed: 12/29/2022]
Abstract
Methanotrophs have recently gained interest as biocatalysts for mitigation of greenhouse gas emission and conversion of methane to value-added products; however, their slow growth has, at least partially, hindered their industrial application. A rapid isolation technique that specifically screens for the fastest-growing methanotrophs was developed using continuous cultivation with gradually increased dilution rates. Environmental samples collected from methane-rich environments were enriched in continuously stirred tank reactors with unrestricted supply of methane and air. The reactor was started at the dilution rate of 0.1 h-1, and the dilution rates were increased with an increment of 0.05 h-1 until the reactor was completely washed out. The shifts in the overall microbial population and methanotrophic community at each step of the isolation procedure were monitored with 16S rRNA amplicon sequencing. The predominant methanotrophic groups recovered after reactor operations were affiliated to the gammaproteobacterial genera Methylomonas and Methylosarcina. The methanotrophic strains isolated from the reactor samples collected at their respective highest dilution rates exhibited specific growth rates up to 0.40 h-1; the highest value reported for methanotrophs. The novel isolation method developed in this study significantly shortened the time and efforts needed for isolation of methanotrophs from environmental samples and was capable of screening for the methanotrophs with the fastest growth rates.
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65
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Fei Q, Puri AW, Smith H, Dowe N, Pienkos PT. Enhanced biological fixation of methane for microbial lipid production by recombinant Methylomicrobium buryatense. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:129. [PMID: 29755588 PMCID: PMC5934843 DOI: 10.1186/s13068-018-1128-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 04/23/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND Due to the success of shale gas development in the US, the production cost of natural gas has been reduced significantly, which in turn has made methane (CH4), the major component of natural gas, a potential alternative substrate for bioconversion processes compared with other high-price raw material sources or edible feedstocks. Therefore, exploring effective ways to use CH4 for the production of biofuels is attractive. Biological fixation of CH4 by methanotrophic bacteria capable of using CH4 as their sole carbon and energy source has obtained great attention for biofuel production from this resource. RESULTS In this study, a fast-growing and lipid-rich methanotroph, Methylomicrobium buryatense 5GB1 and its glycogen-knock-out mutant (AP18) were investigated for the production of lipids derived from intracellular membranes, which are key precursors for the production of green diesel. The effects of culture conditions on cell growth and lipid production were investigated in high cell density cultivation with continuous feeding of CH4 and O2. The highest dry cell weight observed was 21.4 g/L and the maximum lipid productivity observed was 45.4 mg/L/h obtained in batch cultures, which corresponds to a 2-fold enhancement in cell density and 3-fold improvement in lipid production, compared with previous reported data from cultures of 5GB1. A 90% enhancement of lipid content was achieved by limiting the biosynthesis of glycogen in strain AP18. Increased CH4/O2 uptake and CO2 evaluation rates were observed in AP18 cultures suggesting that more carbon substrate and energy are needed for AP18 growth while producing lipids. The lipid produced by M. buryatense was estimated to have a cetane number of 75, which is 50% higher than biofuel standards requested by US and EU. CONCLUSIONS Cell growth and lipid production were significantly influenced by culture conditions for both 5GB1 and AP18. Enhanced lipid production in terms of titer, productivity, and content was achieved under high cell density culture conditions by blocking glycogen accumulation as a carbon sink in the strain AP18. Differences observed in CH4/O2 gas uptake and CO2 evolution rates as well as cell growth and glycogen accumulation between 5GB1 and AP18 suggest changes in the metabolic network between these strains. This bioconversion process provides a promising opportunity to transform CH4 into biofuel molecules and encourages further investigation to elucidate the remarkable CH4 biofixation mechanism used by these bacteria.
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Affiliation(s)
- Qiang Fei
- School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an, China
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Aaron W. Puri
- Department of Chemical Engineering, University of Washington, Seattle, WA USA
| | - Holly Smith
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Nancy Dowe
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Philip. T. Pienkos
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
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66
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Systematic metabolic engineering of Methylomicrobium alcaliphilum 20Z for 2,3-butanediol production from methane. Metab Eng 2018; 47:323-333. [DOI: 10.1016/j.ymben.2018.04.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/12/2018] [Accepted: 04/13/2018] [Indexed: 11/23/2022]
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67
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Garg S, Clomburg JM, Gonzalez R. A modular approach for high-flux lactic acid production from methane in an industrial medium using engineered Methylomicrobium buryatense 5GB1. J Ind Microbiol Biotechnol 2018; 45:379-391. [PMID: 29675615 DOI: 10.1007/s10295-018-2035-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/03/2018] [Indexed: 12/01/2022]
Abstract
Convergence of market drivers such as abundant availability of inexpensive natural gas and increasing awareness of its global warming effects have created new opportunities for the development of small-scale gas-to-liquid (GTL) conversion technologies that can efficiently utilize methane, the primary component of natural gas. Leveraging the unique ability of methanotrophs that use methane as carbon and energy source, biological GTL platforms can be envisioned that are readily deployable at remote petroleum drilling sites where large chemical GTL infrastructure is uneconomical to set-up. Methylomicrobium buryatense, an obligate methanotroph, has gained traction as a potential industrial methanotrophic host because of availability of genetic tools and recent advances in its metabolic engineering. However, progress is impeded by low strain performance and lack of an industrial medium. In this study, we first established a small-scale cultivation platform using Hungate tubes for growth of M. buryatense at medium-to-high-throughput that also enabled 2X faster growth compared to that obtained in traditional glass serum bottles. Then, employing a synthetic biology approach we engineered M. buryatense with varying promoter (inducible and constitutive) and ribosome-binding site combinations, and obtained a strain capable of producing L-lactate from methane at a flux 14-fold higher than previously reported. Finally, we demonstrated L-lactate production in an industrial medium by replacing nitrate with less-expensive ammonium as the nitrogen source. Under these conditions, L-lactate was synthesized at a flux approximately 50-fold higher than that reported previously in a bioreactor system while achieving a titer of 0.6 g/L. These findings position M. buryatense closer to becoming an industrial host strain of choice, and pave new avenues for accelerating methane-to-chemical conversion using synthetic biology.
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Affiliation(s)
- Shivani Garg
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS-667, Houston, TX, 77005, USA
| | - James M Clomburg
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS-667, Houston, TX, 77005, USA
| | - Ramon Gonzalez
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street MS-667, Houston, TX, 77005, USA. .,Department of Bioengineering, Rice University, Houston, 77005, USA.
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68
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Ro SY, Rosenzweig AC. Recent Advances in the Genetic Manipulation of Methylosinus trichosporium OB3b. Methods Enzymol 2018; 605:335-349. [PMID: 29909832 DOI: 10.1016/bs.mie.2018.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Methanotrophic bacteria utilize methane as their sole carbon and energy source. Studies of the model Type II methanotroph Methylosinus trichosporium OB3b have provided insight into multiple aspects of methanotrophy, including methane assimilation, copper accumulation, and metal-dependent gene expression. Development of genetic tools for chromosomal editing was crucial for advancing these studies. Recent interest in methanotroph metabolic engineering has led to new protocols for genetic manipulation of methanotrophs that are effective and simple to use. We have incorporated these newer molecular tools into existing protocols for Ms. trichosporium OB3b. The modifications include additional shuttle and replicative plasmids as well as improved gene delivery and genotyping. The methods described here render gene editing in Ms. trichosporium OB3b efficient and accessible.
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Affiliation(s)
- Soo Y Ro
- Northwestern University, Evanston, IL, United States
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69
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Biological conversion of methane to chemicals and fuels: technical challenges and issues. Appl Microbiol Biotechnol 2018; 102:3071-3080. [PMID: 29492639 DOI: 10.1007/s00253-018-8842-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 02/03/2023]
Abstract
Methane is a promising next-generation carbon feedstock for industrial biotechnology due to its low price and huge availability. Biological conversion of methane to valuable products can mitigate methane-induced global warming as greenhouse gas. There have been challenges for the conversion of methane into various chemicals and fuels using engineered non-native hosts with synthetic methanotrophy or methanotrophs with the reconstruction of synthetic pathways for target products. Herein, we analyze the technical challenges and issues of potent methane bioconversion technology. Pros and cons of metabolic engineering of methanotrophs for methane bioconversion, and perspectives on the bioconversion of methane to chemicals and liquid fuels are discussed.
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70
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Chistoserdova L, Kalyuzhnaya MG. Current Trends in Methylotrophy. Trends Microbiol 2018; 26:703-714. [PMID: 29471983 DOI: 10.1016/j.tim.2018.01.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 01/18/2018] [Accepted: 01/30/2018] [Indexed: 11/26/2022]
Abstract
Methylotrophy is a field of study dealing with microorganisms capable of utilization of compounds devoid of carbon-carbon bonds (C1 compounds). In this review, we highlight several emerging trends in methylotrophy. First, we discuss the significance of the recent discovery of lanthanide-dependent alcohol dehydrogenases for understanding both the occurrence and the distribution of methylotrophy functions among bacteria, and then we discuss the newly appreciated role of lanthanides in biology. Next, we describe the detection of other methylotrophy pathways across novel bacterial taxa and insights into the evolution of methylotrophy. Further, data are presented on the occurrence and activity of aerobic methylotrophs in hypoxic and anoxic environments, questioning the prior assumptions on niche separation of aerobic and anaerobic methylotrophy. The concept of communal function in aerobic methane oxidation is also briefly discussed. Finally, we review recent research in engineering methylotrophs for biotechnological applications as well as recent progress in engineering synthetic methylotrophy.
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71
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Methane utilization in Methylomicrobium alcaliphilum 20Z R: a systems approach. Sci Rep 2018; 8:2512. [PMID: 29410419 PMCID: PMC5802761 DOI: 10.1038/s41598-018-20574-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 01/22/2018] [Indexed: 12/20/2022] Open
Abstract
Biological methane utilization, one of the main sinks of the greenhouse gas in nature, represents an attractive platform for production of fuels and value-added chemicals. Despite the progress made in our understanding of the individual parts of methane utilization, our knowledge of how the whole-cell metabolic network is organized and coordinated is limited. Attractive growth and methane-conversion rates, a complete and expert-annotated genome sequence, as well as large enzymatic, 13C-labeling, and transcriptomic datasets make Methylomicrobium alcaliphilum 20ZR an exceptional model system for investigating methane utilization networks. Here we present a comprehensive metabolic framework of methane and methanol utilization in M. alcaliphilum 20ZR. A set of novel metabolic reactions governing carbon distribution across central pathways in methanotrophic bacteria was predicted by in-silico simulations and confirmed by global non-targeted metabolomics and enzymatic evidences. Our data highlight the importance of substitution of ATP-linked steps with PPi-dependent reactions and support the presence of a carbon shunt from acetyl-CoA to the pentose-phosphate pathway and highly branched TCA cycle. The diverged TCA reactions promote balance between anabolic reactions and redox demands. The computational framework of C1-metabolism in methanotrophic bacteria can represent an efficient tool for metabolic engineering or ecosystem modeling.
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72
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Chistoserdova L. Applications of methylotrophs: can single carbon be harnessed for biotechnology? Curr Opin Biotechnol 2018; 50:189-194. [PMID: 29414059 DOI: 10.1016/j.copbio.2018.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/07/2017] [Accepted: 01/11/2018] [Indexed: 02/06/2023]
Abstract
This review summarizes developments in the field of applied research involving microbial conversion of single carbon compounds (methane, methanol, CO2). The potential of the microorganisms involved in biotechnological applications could be realized via engineering native C1 utilizers toward higher output of value-added compounds, including biofuels, or via production of value chemicals as parts of novel, heterologously expressed biochemical pathways. Alternatively, C1 metabolism could be implemented in traditional industrial platforms (Escherichia coli, yeast), via introduction of specific metabolic modules. Most recent research spanning both approaches is covered. The potential of C1 utilizers in biomining of rare Earth elements, as well as the potential of C1 consuming microbial consortia in industrial applications are discussed.
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Affiliation(s)
- Ludmila Chistoserdova
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States.
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73
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Walsh R. Innovating New Bioconversion Pathways. Ind Biotechnol (New Rochelle N Y) 2018. [DOI: 10.1089/ind.2018.29113.rwa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Robert Walsh
- Senior Vice President, Energy Sector, Intrexon, Germantown, MD
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74
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Collins DA, Kalyuzhnaya MG. Navigating methane metabolism: Enzymes, compartments, and networks. Methods Enzymol 2018; 613:349-383. [DOI: 10.1016/bs.mie.2018.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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75
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Bennett RK, Steinberg LM, Chen W, Papoutsakis ET. Engineering the bioconversion of methane and methanol to fuels and chemicals in native and synthetic methylotrophs. Curr Opin Biotechnol 2017; 50:81-93. [PMID: 29216497 DOI: 10.1016/j.copbio.2017.11.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/14/2017] [Accepted: 11/15/2017] [Indexed: 10/18/2022]
Abstract
Methylotrophy describes the ability of organisms to utilize reduced one-carbon compounds, notably methane and methanol, as growth and energy sources. Abundant natural gas supplies, composed primarily of methane, have prompted interest in using these compounds, which are more reduced than sugars, as substrates to improve product titers and yields of bioprocesses. Engineering native methylotophs or developing synthetic methylotrophs are emerging fields to convert methane and methanol into fuels and chemicals under aerobic and anaerobic conditions. This review discusses recent progress made toward engineering native methanotrophs for aerobic and anaerobic methane utilization and synthetic methylotrophs for methanol utilization. Finally, strategies to overcome the limitations involved with synthetic methanol utilization, notably methanol dehydrogenase kinetics and ribulose 5-phosphate regeneration, are discussed.
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Affiliation(s)
- R Kyle Bennett
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, DE 19716, USA; The Delaware Biotechnology Institute, Molecular Biotechnology Laboratory, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA
| | - Lisa M Steinberg
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, DE 19716, USA; The Delaware Biotechnology Institute, Molecular Biotechnology Laboratory, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA
| | - Wilfred Chen
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, DE 19716, USA
| | - Eleftherios T Papoutsakis
- Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, DE 19716, USA; The Delaware Biotechnology Institute, Molecular Biotechnology Laboratory, University of Delaware, 15 Innovation Way, Newark, DE 19711, USA.
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76
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Pieja AJ, Morse MC, Cal AJ. Methane to bioproducts: the future of the bioeconomy? Curr Opin Chem Biol 2017; 41:123-131. [PMID: 29197255 DOI: 10.1016/j.cbpa.2017.10.024] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 10/07/2017] [Accepted: 10/20/2017] [Indexed: 11/15/2022]
Abstract
Methanotrophs have been studied since the 1970s, but interest has increased tremendously in recent years due to their potential to transform methane into valuable bioproducts. The vast quantity of available methane and the low price of methane as natural gas have helped to spur this interest. The most well-studied, biologically-derived products from methane include methanol, polyhydroxyalkanoates, and single cell protein. However, many other high-interest chemicals such as biofuels or high-value products such as ectoine could be made industrially relevant through metabolic engineering. Although challenges must be overcome to achieve commercialization of biologically manufactured methane-to-products, taking a holistic view of the production process or radically re-imagining pathways could lead to a future bioeconomy with methane as the primary feedstock.
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Affiliation(s)
- Allison J Pieja
- Mango Materials, 490 Lake Park Ave #16098, Oakland, CA 94610, United States.
| | - Molly C Morse
- Mango Materials, 490 Lake Park Ave #16098, Oakland, CA 94610, United States
| | - Andrew J Cal
- USDA-ARS-WRRC, Bioproducts Research Unit, 800 Buchanan Street, Albany, CA 94710, United States
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77
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Gilman A, Fu Y, Hendershott M, Chu F, Puri AW, Smith AL, Pesesky M, Lieberman R, Beck DAC, Lidstrom ME. Oxygen-limited metabolism in the methanotroph Methylomicrobium buryatense 5GB1C. PeerJ 2017; 5:e3945. [PMID: 29062611 PMCID: PMC5652258 DOI: 10.7717/peerj.3945] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/30/2017] [Indexed: 11/20/2022] Open
Abstract
The bacteria that grow on methane aerobically (methanotrophs) support populations of non-methanotrophs in the natural environment by excreting methane-derived carbon. One group of excreted compounds are short-chain organic acids, generated in highest abundance when cultures are grown under O2-starvation. We examined this O2-starvation condition in the methanotroph Methylomicrobium buryatense 5GB1. The M. buryatense 5GB1 genome contains homologs for all enzymes necessary for a fermentative metabolism, and we hypothesize that a metabolic switch to fermentation can be induced by low-O2 conditions. Under prolonged O2-starvation in a closed vial, this methanotroph increases the amount of acetate excreted about 10-fold, but the formate, lactate, and succinate excreted do not respond to this culture condition. In bioreactor cultures, the amount of each excreted product is similar across a range of growth rates and limiting substrates, including O2-limitation. A set of mutants were generated in genes predicted to be involved in generating or regulating excretion of these compounds and tested for growth defects, and changes in excretion products. The phenotypes and associated metabolic flux modeling suggested that in M. buryatense 5GB1, formate and acetate are excreted in response to redox imbalance. Our results indicate that even under O2-starvation conditions, M. buryatense 5GB1 maintains a metabolic state representing a combination of fermentation and respiration metabolism.
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Affiliation(s)
- Alexey Gilman
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | - Yanfen Fu
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | | | | | - Aaron W Puri
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | | | - Mitchell Pesesky
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America
| | - Rose Lieberman
- Department of Biology, George Washington University, Washington, D.C., USA
| | - David A C Beck
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America.,eScience Institute, University of Washington, Seattle, WA, USA
| | - Mary E Lidstrom
- Department of Chemical Engineering, University of Washington, Seattle, WA, United States of America.,Department of Microbiology, University of Washington, Seattle, WA, USA
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78
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Tan SZ, Prather KL. Dynamic pathway regulation: recent advances and methods of construction. Curr Opin Chem Biol 2017; 41:28-35. [PMID: 29059607 DOI: 10.1016/j.cbpa.2017.10.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 12/26/2022]
Abstract
Microbial cell factories are a renewable source for the production of biofuels and valuable chemicals. Dynamic pathway regulation has proved successful in improving production of molecules by balancing flux between growth of cells and production of metabolites. Systems for autonomous induction of pathway regulation are increasingly being developed, which include metabolite responsive promoters, biosensors, and quorum sensing systems. Since engineering such systems are dependent on the available methods for controlling protein abundance in the desired host, we review recent tools used for gene repression at the transcriptional, post-transcriptional and post-translational levels in Escherichia coli and Saccharomyces cerevisiae. These approaches may facilitate pathway engineering for biofuel and biochemical production.
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Affiliation(s)
- Sue Zanne Tan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kristala Lj Prather
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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79
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Ishikawa M, Tanaka Y, Suzuki R, Kimura K, Tanaka K, Kamiya K, Ito H, Kato S, Kamachi T, Hori K, Nakanishi S. Real-time monitoring of intracellular redox changes in Methylococcus capsulatus (Bath) for efficient bioconversion of methane to methanol. BIORESOURCE TECHNOLOGY 2017; 241:1157-1161. [PMID: 28578808 DOI: 10.1016/j.biortech.2017.05.107] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 06/07/2023]
Abstract
This study aimed to develop a novel method for real-time monitoring of the intracellular redox states in a methanotroph Methylococcus capsulatus, using Peredox as a genetically encoded fluorescent sensor of the NADH:NAD+ ratio. As expected, the fluorescence derived from the Peredox-expressing M. capsulatus transformant increased by supplementation of electron donor compounds (methane and formate), while it decreased by specifically inhibiting the methanol oxidation reaction. Electrochemical measurements confirmed that the Peredox fluorescence reliably represents the intracellular redox changes. This study is the first to construct a reliable redox-monitoring method for methanotrophs, which will facilitate to develop more efficient methane-to-methanol bioconversion processes.
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Affiliation(s)
- Masahito Ishikawa
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan; Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Yuya Tanaka
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Risa Suzuki
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Kota Kimura
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Kenya Tanaka
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Kazuhide Kamiya
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan; Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Hidehiro Ito
- Education Academy of Computational Life Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Souichiro Kato
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido 062-8517, Japan
| | - Toshiaki Kamachi
- Department of Life Science and Technology, Graduated School of Bioscience and Biotechnology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Katsutoshi Hori
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Shuji Nakanishi
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan; Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
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80
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Henard CA, Smith HK, Guarnieri MT. Phosphoketolase overexpression increases biomass and lipid yield from methane in an obligate methanotrophic biocatalyst. Metab Eng 2017; 41:152-158. [DOI: 10.1016/j.ymben.2017.03.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/17/2017] [Accepted: 03/31/2017] [Indexed: 12/20/2022]
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81
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Bagi Z, Ács N, Böjti T, Kakuk B, Rákhely G, Strang O, Szuhaj M, Wirth R, Kovács KL. Biomethane: The energy storage, platform chemical and greenhouse gas mitigation target. Anaerobe 2017; 46:13-22. [PMID: 28341558 DOI: 10.1016/j.anaerobe.2017.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/21/2017] [Accepted: 03/02/2017] [Indexed: 01/10/2023]
Abstract
Results in three areas of anaerobic microbiology in which methane formation and utilization plays central part are reviewed. a.) Bio-methane formation by reduction of carbon dioxide in the power-to-gas process and the various possibilities of improvement of the process is a very intensively studied topic recently. From the numerous potential methods of exploiting methane of biological origin two aspects are discussed in detail. b.) Methane can serve as a platform chemical in various chemical and biochemical synthetic processes. Particular emphasis is put on the biochemical conversion pathways involving methanotrophs and their methane monooxygenase-catalyzed reactions leading to various small molecules and polymeric materials such as extracellular polysaccharides, polyhydroxyalkanoates and proteins. c.) The third area covered concerns methane-consuming reactions and methane emission mitigation. These investigations comprise the anaerobic microbiology of ruminants and approaches to diminishing methane emissions from ruminant animals.
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Affiliation(s)
- Zoltán Bagi
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Norbert Ács
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Tamás Böjti
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Balázs Kakuk
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Gábor Rákhely
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary; Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Temesvári Krt. 62, Szeged 6726, Hungary.
| | - Orsolya Strang
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Márk Szuhaj
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Roland Wirth
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.
| | - Kornél L Kovács
- Department of Biotechnology, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary; Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences, Temesvári Krt. 62, Szeged 6726, Hungary; Department of Oral Biology and Experimental Dental Research, University of Szeged, Tisza L. Krt. 64, Szeged 6720, Hungary.
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Stone KA, Shah D, Kim MH, Roberts NRM, He QP, Wang J. A novel soft sensor approach for estimating individual biomass in mixed cultures. Biotechnol Prog 2017; 33:347-354. [DOI: 10.1002/btpr.2453] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 01/18/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Kyle A. Stone
- Department of Chemical EngineeringAuburn UniversityAuburn AL36849
| | - Devarshi Shah
- Department of Chemical EngineeringAuburn UniversityAuburn AL36849
| | - Min Hea Kim
- Department of Chemical EngineeringAuburn UniversityAuburn AL36849
| | | | - Q. Peter He
- Department of Chemical EngineeringAuburn UniversityAuburn AL36849
| | - Jin Wang
- Department of Chemical EngineeringAuburn UniversityAuburn AL36849
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83
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Demidenko A, Akberdin IR, Allemann M, Allen EE, Kalyuzhnaya MG. Fatty Acid Biosynthesis Pathways in Methylomicrobium buryatense 5G(B1). Front Microbiol 2017; 7:2167. [PMID: 28119683 PMCID: PMC5222806 DOI: 10.3389/fmicb.2016.02167] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/23/2016] [Indexed: 01/02/2023] Open
Abstract
Methane utilization by methanotrophic bacteria is an attractive application for biotechnological conversion of natural or biogas into high-added-value products. Haloalcaliphilic methanotrophic bacteria belonging to the genus Methylomicrobium are among the most promising strains for methane-based biotechnology, providing easy and inexpensive cultivation, rapid growth, and the availability of established genetic tools. A number of methane bioconversions using these microbial cultures have been discussed, including the derivation of biodiesel, alkanes, and OMEGA-3 supplements. These compounds are derived from bacterial fatty acid pools. Here, we investigate fatty acid biosynthesis in Methylomicrobium buryatense 5G(B1). Most of the genes homologous to typical Type II fatty acid biosynthesis pathways could be annotated by bioinformatics analyses, with the exception of fatty acid transport and regulatory elements. Different approaches for improving fatty acid accumulation were investigated. These studies indicated that both fatty acid degradation and acetyl- and malonyl-CoA levels are bottlenecks for higher level fatty acid production. The best strain generated in this study synthesizes 111 ± 2 mg/gDCW of extractable fatty acids, which is ~20% more than the original strain. A candidate gene for fatty acid biosynthesis regulation, farE, was identified and studied. Its deletion resulted in drastic changes to the fatty acid profile, leading to an increased pool of C18-fatty acid methyl ester. The FarE-regulon was further investigated by RNA-seq analysis of gene expression in farE-knockout mutants and farE-overexpressing strains. These gene profiles highlighted a novel set of enzymes and regulators involved in fatty acid biosynthesis. The gene expression and fatty acid profiles of the different farE-strains support the hypothesis that metabolic fluxes upstream of fatty acid biosynthesis restrict fatty acid production in the methanotroph.
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Affiliation(s)
- Aleksandr Demidenko
- Department of Biology, San Diego State University, Campanile DriveSan Diego, CA, USA; Scripps Institution of Oceanography, University of California San Diego, Gilman DriveLa Jolla, CA, USA
| | - Ilya R Akberdin
- Department of Biology, San Diego State University, Campanile Drive San Diego, CA, USA
| | - Marco Allemann
- Scripps Institution of Oceanography, University of California San Diego, Gilman Drive La Jolla, CA, USA
| | - Eric E Allen
- Scripps Institution of Oceanography, University of California San Diego, Gilman Drive La Jolla, CA, USA
| | - Marina G Kalyuzhnaya
- Department of Biology, San Diego State University, Campanile Drive San Diego, CA, USA
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84
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Clomburg JM, Crumbley AM, Gonzalez R. Industrial biomanufacturing: The future of chemical production. Science 2017; 355:355/6320/aag0804. [DOI: 10.1126/science.aag0804] [Citation(s) in RCA: 271] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/21/2016] [Indexed: 12/18/2022]
Abstract
The current model for industrial chemical manufacturing employs large-scale megafacilities that benefit from economies of unit scale. However, this strategy faces environmental, geographical, political, and economic challenges associated with energy and manufacturing demands. We review how exploiting biological processes for manufacturing (i.e., industrial biomanufacturing) addresses these concerns while also supporting and benefiting from economies of unit number. Key to this approach is the inherent small scale and capital efficiency of bioprocesses and the ability of engineered biocatalysts to produce designer products at high carbon and energy efficiency with adjustable output, at high selectivity, and under mild process conditions. The biological conversion of single-carbon compounds represents a test bed to establish this paradigm, enabling rapid, mobile, and widespread deployment, access to remote and distributed resources, and adaptation to new and changing markets.
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85
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Kim S, Lee W, Song I, Kwon Y, Yun S, Park S, Cho S, Oh BK, Oh HB, Lee J. Production of uracil from methane by a newly isolated Methylomonas sp. SW1. J Biotechnol 2016; 240:43-47. [DOI: 10.1016/j.jbiotec.2016.10.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/16/2016] [Accepted: 10/20/2016] [Indexed: 11/28/2022]
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86
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McAnulty MJ, Poosarla VG, Li J, Soo VWC, Zhu F, Wood TK. Metabolic engineering of Methanosarcina acetivorans for lactate production from methane. Biotechnol Bioeng 2016; 114:852-861. [PMID: 27800599 DOI: 10.1002/bit.26208] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/13/2016] [Accepted: 10/25/2016] [Indexed: 01/12/2023]
Abstract
We previously demonstrated anaerobic conversion of the greenhouse gas methane into acetate using an engineered archaeon that produces methyl-coenzyme M reductase (Mcr) from unculturable microorganisms from a microbial mat in the Black Sea to create the first culturable prokaryote that reverses methanogenesis and grows anaerobically on methane. In this work, we further engineered the same host with the goal of converting methane into butanol. Instead, we discovered a process for converting methane to a secreted valuable product, L-lactate, with sufficient optical purity for synthesizing the biodegradable plastic poly-lactic acid. We determined that the 3-hydroxybutyryl-CoA dehydrogenase (Hbd) from Clostridium acetobutylicum is responsible for lactate production. This work demonstrates the first metabolic engineering of a methanogen with a synthetic pathway; in effect, we produce a novel product (lactate) from a novel substrate (methane) by cloning the three genes for Mcr and one for Hbd. We further demonstrate the utility of anaerobic methane conversion with an increased lactate yield compared to aerobic methane conversion to lactate. Biotechnol. Bioeng. 2017;114: 852-861. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Michael J McAnulty
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 168 020-4400
| | - Venkata Giridhar Poosarla
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 168 020-4400
| | - Jine Li
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 168 020-4400
| | - Valerie W C Soo
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 168 020-4400
| | - Fayin Zhu
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 168 020-4400
| | - Thomas K Wood
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 168 020-4400.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802-4400
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87
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Strong PJ, Kalyuzhnaya M, Silverman J, Clarke WP. A methanotroph-based biorefinery: Potential scenarios for generating multiple products from a single fermentation. BIORESOURCE TECHNOLOGY 2016; 215:314-323. [PMID: 27146469 DOI: 10.1016/j.biortech.2016.04.099] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 04/17/2016] [Accepted: 04/19/2016] [Indexed: 05/12/2023]
Abstract
Methane, a carbon source for methanotrophic bacteria, is the principal component of natural gas and is produced during anaerobic digestion of organic matter (biogas). Methanotrophs are a viable source of single cell protein (feed supplement) and can produce various products, since they accumulate osmolytes (e.g. ectoine, sucrose), phospholipids (potential biofuels) and biopolymers (polyhydroxybutyrate, glycogen), among others. Other cell components, such as surface layers, metal chelating proteins (methanobactin), enzymes (methane monooxygenase) or heterologous proteins hold promise as future products. Here, scenarios are presented where ectoine, polyhydroxybutyrate or protein G are synthesised as the primary product, in conjunction with a variety of ancillary products that could enhance process viability. Single or dual-stage processes and volumetric requirements for bioreactors are discussed, in terms of an annual biomass output of 1000 tonnesyear(-1). Product yields are discussed in relation to methane and oxygen consumption and organic waste generation.
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Affiliation(s)
- P J Strong
- Centre for Solid Waste Bioprocessing, School of Civil Engineering, School of Chemical Engineering, The University of Queensland, Brisbane 4072, Australia.
| | - M Kalyuzhnaya
- Biology Department, San Diego State University, San Diego, CA 92182-4614, United States
| | - J Silverman
- Calysta, 1140 O'Brien Drive, Menlo Park, CA 94025, United States
| | - W P Clarke
- Centre for Solid Waste Bioprocessing, School of Civil Engineering, School of Chemical Engineering, The University of Queensland, Brisbane 4072, Australia
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88
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Lawton TJ, Rosenzweig AC. Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion. J Am Chem Soc 2016; 138:9327-40. [PMID: 27366961 PMCID: PMC5242187 DOI: 10.1021/jacs.6b04568] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Biological conversion of natural gas to liquids (Bio-GTL) represents an immense economic opportunity. In nature, aerobic methanotrophic bacteria and anaerobic archaea are able to selectively oxidize methane using methane monooxygenase (MMO) and methyl coenzyme M reductase (MCR) enzymes. Although significant progress has been made toward genetically manipulating these organisms for biotechnological applications, the enzymes themselves are slow, complex, and not recombinantly tractable in traditional industrial hosts. With turnover numbers of 0.16-13 s(-1), these enzymes pose a considerable upstream problem in the biological production of fuels or chemicals from methane. Methane oxidation enzymes will need to be engineered to be faster to enable high volumetric productivities; however, efforts to do so and to engineer simpler enzymes have been minimally successful. Moreover, known methane-oxidizing enzymes have different expression levels, carbon and energy efficiencies, require auxiliary systems for biosynthesis and function, and vary considerably in terms of complexity and reductant requirements. The pros and cons of using each methane-oxidizing enzyme for Bio-GTL are considered in detail. The future for these enzymes is bright, but a renewed focus on studying them will be critical to the successful development of biological processes that utilize methane as a feedstock.
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Affiliation(s)
- Thomas J Lawton
- Departments of Molecular Biosciences and of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
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89
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Desai SH, Koryakina I, Case AE, Toney MD, Atsumi S. Biological conversion of gaseous alkenes to liquid chemicals. Metab Eng 2016; 38:98-104. [PMID: 27424209 DOI: 10.1016/j.ymben.2016.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/11/2016] [Indexed: 10/21/2022]
Abstract
Industrial gas-to-liquid (GTL) technologies are well developed. They generally employ syngas, require complex infrastructure, and need high capital investment to be economically viable. Alternatively, biological conversion has the potential to be more efficient, and easily deployed to remote areas on relatively small scales for the utilization of otherwise stranded resources. The present study demonstrates a novel biological GTL process in which engineered Escherichia coli converts C2-C4 gaseous alkenes into liquid diols. Diols are versatile industrially important chemicals, used routinely as antifreeze agents, polymer precursors amongst many other applications. Heterologous co-expression of a monooxygenase and an epoxide hydrolase in E. coli allows whole cell conversion of C2-C4 alkenes for the formation of ethylene glycol, 1,2-propanediol, 1,2-butanediol, and 2,3-butanediol at ambient temperature and pressure in one pot. Increasing intracellular NADH supply via addition of formate and a formate dehydrogenase increases ethylene glycol production titers, resulting in an improved productivity of 9mg/L/h and a final titer of 250mg/L. This represents a novel biological method for GTL conversion of alkenes to industrially valuable diols.
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Affiliation(s)
- Shuchi H Desai
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Irina Koryakina
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Anna E Case
- Department of Chemistry, University of California-Davis, Davis, CA, USA
| | - Michael D Toney
- Department of Chemistry, University of California-Davis, Davis, CA, USA.
| | - Shota Atsumi
- Department of Chemistry, University of California-Davis, Davis, CA, USA.
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