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Metabolic engineering of Escherichia coli for production of biodiesel from fatty alcohols and acetyl-CoA. Appl Microbiol Biotechnol 2015. [PMID: 26205521 DOI: 10.1007/s00253-015-6809-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Microbial production of biodiesel from renewable feedstock has attracted intensive attention. Biodiesel is known to be produced from short-chain alcohols and fatty acyl-CoAs through the expression of wax ester synthase/fatty acyl-CoA: diacylglycerol acyltransferase that catalyzes the esterification of short-chain alcohols and fatty acyl-CoAs. Here, we engineered Escherichia coli to produce various fatty alcohol acetate esters, which depend on the expression of Saccharomyces cerevisiae alcohol acetyltransferase ATF1 that catalyzes the esterification of fatty alcohols and acetyl-CoA. The fatty acid biosynthetic pathways generate fatty acyl-ACPs, fatty acyl-CoAs, or fatty acids, which can be converted to fatty alcohols by fatty acyl-CoA reductase, fatty acyl-ACP reductase, or carboxylic acid reductase, respectively. This study showed the biosynthesis of biodiesel from three fatty acid biosynthetic pathway intermediates.
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202
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Tang X, Lee J, Chen WN. Engineering the fatty acid metabolic pathway in Saccharomyces cerevisiae for advanced biofuel production. Metab Eng Commun 2015; 2:58-66. [PMID: 34150509 PMCID: PMC8193251 DOI: 10.1016/j.meteno.2015.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 06/22/2015] [Accepted: 06/22/2015] [Indexed: 11/30/2022] Open
Abstract
Fatty acid-derived fuels and chemicals have attracted a great deal of attention in recent decades, due to their following properties of high compatibility to gasoline-based fuels and existing infrastructure for their direct utilization, storage and distribution. The yeast Saccharomyces cerevisiae is the ideal biofuel producing candidate, based on the wealth of available genetic information and versatile tools designed to manipulate its metabolic pathways. Engineering the fatty acid metabolic pathways in S. cerevisiae is an effective strategy to increase its fatty acid biosynthesis and provide more pathway precursors for production of targeted products. This review summarizes the recent progress in metabolic engineering of yeast cells for fatty acids and fatty acid derivatives production, including the regulation of acetyl-CoA biosynthesis, NADPH production, fatty acid elongation, and the accumulation of activated precursors of fatty acids for converting enzymes. By introducing specific enzymes in the engineered strains, a powerful platform with a scalable, controllable and economic route for advanced biofuel production has been established. Recent progress in metabolic engineering for enhanced fatty acid production. Regulation of acetyl-CoA, NADPH pathway for fatty acid synthesis. Regulation of elongation and catabolic pathway to strength fatty acid synthesis. Enhanced production of activated precursors for fatty acid derivatives production.
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Affiliation(s)
- Xiaoling Tang
- School of Chemical and Biomedical Engineering, College of Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
| | - Jaslyn Lee
- School of Chemical and Biomedical Engineering, College of Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
| | - Wei Ning Chen
- School of Chemical and Biomedical Engineering, College of Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
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203
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Biocatalysed reduction of carboxylic acids to primary alcohols in aqueous medium: A novel synthetic capability of the zygomycete fungus Syncephalastrum racemosum. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2015.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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204
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Exploring the synthetic applicability of a new carboxylic acid reductase from Segniliparus rotundus DSM 44985. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2015.01.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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205
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206
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Biosynthesis of odd-chain fatty alcohols in Escherichia coli. Metab Eng 2015; 29:113-123. [PMID: 25773521 DOI: 10.1016/j.ymben.2015.03.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/16/2015] [Accepted: 03/04/2015] [Indexed: 11/21/2022]
Abstract
Engineered microbes offer the opportunity to design and implement artificial molecular pathways for renewable production of tailored chemical commodities. Targeted biosynthesis of odd-chain fatty alcohols is very challenging in microbe, due to the specificity of fatty acids synthase for two-carbon unit elongation. Here, we developed a novel strategy to directly tailor carbon number in fatty aldehydes formation step by incorporating α-dioxygenase (αDOX) from Oryza sativa (rice) into Escherichia coli αDOX oxidizes Cn fatty acids (even-chain) to form Cn-1 fatty aldehydes (odd-chain). Through combining αDOX with fatty acyl-acyl carrier protein (-ACP) thioesterase (TE) and aldehyde reductase (AHR), the medium odd-chain fatty alcohols profile (C11, C13, C15) was firstly established in E. coli. Also, medium even-chain alkanes (C12, C14) were obtained by substitution of AHR to aldehyde decarbonylase (AD). The titer of odd-chain fatty alcohols was improved from 7.4mg/L to 101.5mg/L in tube cultivation by means of fine-tuning endogenous fatty acyl-ACP TE (TesA'), αDOX, AHRs and the genes involved in fatty acids metabolism pathway. Through high cell density fed-batch fermentation, a titer of 1.95g/L odd-chain fatty alcohols was achieved, which was the highest reported titer in E. coli. Our system has greatly expanded the current microbial fatty alcohols profile that provides a new brand solution for producing complex and desired molecules in microbes.
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207
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Amaral LDS, Rodrigues-Filho E. Aryl carboxylic acid reduction and further reactions with GABA and glucose promoted by whole cells of Xylaria arbuscula. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2015.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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208
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Buijs NA, Zhou YJ, Siewers V, Nielsen J. Long-chain alkane production by the yeast Saccharomyces cerevisiae. Biotechnol Bioeng 2015; 112:1275-9. [PMID: 25545362 DOI: 10.1002/bit.25522] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/17/2014] [Accepted: 12/08/2014] [Indexed: 11/10/2022]
Abstract
In the past decade industrial-scale production of renewable transportation biofuels has been developed as an alternative to fossil fuels, with ethanol as the most prominent biofuel and yeast as the production organism of choice. However, ethanol is a less efficient substitute fuel for heavy-duty and maritime transportation as well as aviation due to its low energy density. Therefore, new types of biofuels, such as alkanes, are being developed that can be used as drop-in fuels and can substitute gasoline, diesel, and kerosene. Here, we describe for the first time the heterologous biosynthesis of long-chain alkanes by the yeast Saccharomyces cerevisiae. We show that elimination of the hexadecenal dehydrogenase Hfd1 and expression of a redox system are essential for alkane biosynthesis in yeast. Deletion of HFD1 together with expression of an alkane biosynthesis pathway resulted in the production of the alkanes tridecane, pentadecane, and heptadecane. Our study provides a proof of principle for producing long-chain alkanes in the industrial workhorse S. cerevisiae, which was so far limited to bacteria. We anticipate that these findings will be a key factor for further yeast engineering to enable industrial production of alkane based drop-in biofuels, which can allow the biofuel industry to diversify beyond bioethanol.
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Affiliation(s)
- Nicolaas A Buijs
- Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
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Abstract
Aldehydes are a class of chemicals with many industrial uses. Several aldehydes are responsible for flavors and fragrances present in plants, but aldehydes are not known to accumulate in most natural microorganisms. In many cases, microbial production of aldehydes presents an attractive alternative to extraction from plants or chemical synthesis. During the past 2 decades, a variety of aldehyde biosynthetic enzymes have undergone detailed characterization. Although metabolic pathways that result in alcohol synthesis via aldehyde intermediates were long known, only recent investigations in model microbes such as Escherichia coli have succeeded in minimizing the rapid endogenous conversion of aldehydes into their corresponding alcohols. Such efforts have provided a foundation for microbial aldehyde synthesis and broader utilization of aldehydes as intermediates for other synthetically challenging biochemical classes. However, aldehyde toxicity imposes a practical limit on achievable aldehyde titers and remains an issue of academic and commercial interest. In this minireview, we summarize published efforts of microbial engineering for aldehyde synthesis, with an emphasis on de novo synthesis, engineered aldehyde accumulation in E. coli, and the challenge of aldehyde toxicity.
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210
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Menon N, Pásztor A, Menon BRK, Kallio P, Fisher K, Akhtar MK, Leys D, Jones PR, Scrutton NS. A microbial platform for renewable propane synthesis based on a fermentative butanol pathway. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:61. [PMID: 25866563 PMCID: PMC4392459 DOI: 10.1186/s13068-015-0231-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/23/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND Propane (C3H8) is a volatile hydrocarbon with highly favourable physicochemical properties as a fuel, in addition to existing global markets and infrastructure for storage, distribution and utilization in a wide range of applications. Consequently, propane is an attractive target product in research aimed at developing new renewable alternatives to complement currently used petroleum-derived fuels. This study focuses on the construction and evaluation of alternative microbial biosynthetic pathways for the production of renewable propane. The new pathways utilize CoA intermediates that are derived from clostridial-like fermentative butanol pathways and are therefore distinct from the first microbial propane pathways recently engineered in Escherichia coli. RESULTS We report the assembly and evaluation of four different synthetic pathways for the production of propane and butanol, designated a) atoB-adhE2 route, b) atoB-TPC7 route, c) nphT7-adhE2 route and d) nphT7-TPC7 route. The highest butanol titres were achieved with the atoB-adhE2 (473 ± 3 mg/L) and atoB-TPC7 (163 ± 2 mg/L) routes. When aldehyde deformylating oxygenase (ADO) was co-expressed with these pathways, the engineered hosts also produced propane. The atoB-TPC7-ADO pathway was the most effective in producing propane (220 ± 3 μg/L). By (i) deleting competing pathways, (ii) including a previously designed ADOA134F variant with an enhanced specificity towards short-chain substrates and (iii) including a ferredoxin-based electron supply system, the propane titre was increased (3.40 ± 0.19 mg/L). CONCLUSIONS This study expands the metabolic toolbox for renewable propane production and provides new insight and understanding for the development of next-generation biofuel platforms. In developing an alternative CoA-dependent fermentative butanol pathway, which includes an engineered ADO variant (ADOA134F), the study addresses known limitations, including the low bio-availability of butyraldehyde precursors and poor activity of ADO with butyraldehyde. Graphical abstractPropane synthesis derived from a fermentative butanol pathway is enabled by metabolic engineering.
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Affiliation(s)
- Navya Menon
- />BBSRC/EPSRC Centre for Synthetic Biology of Fine and Speciality Chemicals, Manchester Institute of Biotechnology, Faculty of Life Sciences, 131 Princess Street, The University of Manchester, Manchester, M1 7DN UK
| | - András Pásztor
- />Molecular Plant Biology, Department of Biochemistry, Tykistökatu 6A 6krs, University of Turku, FI 20014 TURUN YLIOPISTO, Turku, Finland
| | - Binuraj RK Menon
- />BBSRC/EPSRC Centre for Synthetic Biology of Fine and Speciality Chemicals, Manchester Institute of Biotechnology, Faculty of Life Sciences, 131 Princess Street, The University of Manchester, Manchester, M1 7DN UK
| | - Pauli Kallio
- />Molecular Plant Biology, Department of Biochemistry, Tykistökatu 6A 6krs, University of Turku, FI 20014 TURUN YLIOPISTO, Turku, Finland
| | - Karl Fisher
- />BBSRC/EPSRC Centre for Synthetic Biology of Fine and Speciality Chemicals, Manchester Institute of Biotechnology, Faculty of Life Sciences, 131 Princess Street, The University of Manchester, Manchester, M1 7DN UK
| | - M Kalim Akhtar
- />Molecular Plant Biology, Department of Biochemistry, Tykistökatu 6A 6krs, University of Turku, FI 20014 TURUN YLIOPISTO, Turku, Finland
| | - David Leys
- />BBSRC/EPSRC Centre for Synthetic Biology of Fine and Speciality Chemicals, Manchester Institute of Biotechnology, Faculty of Life Sciences, 131 Princess Street, The University of Manchester, Manchester, M1 7DN UK
| | - Patrik R Jones
- />Molecular Plant Biology, Department of Biochemistry, Tykistökatu 6A 6krs, University of Turku, FI 20014 TURUN YLIOPISTO, Turku, Finland
- />Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London, SW7 2AZ UK
| | - Nigel S Scrutton
- />BBSRC/EPSRC Centre for Synthetic Biology of Fine and Speciality Chemicals, Manchester Institute of Biotechnology, Faculty of Life Sciences, 131 Princess Street, The University of Manchester, Manchester, M1 7DN UK
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211
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Ling H, Pratomo Juwono NK, Teo WS, Liu R, Leong SSJ, Chang MW. Engineering transcription factors to improve tolerance against alkane biofuels in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:231. [PMID: 26719765 PMCID: PMC4696261 DOI: 10.1186/s13068-015-0411-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 12/04/2015] [Indexed: 05/22/2023]
Abstract
BACKGROUND Biologically produced alkanes can be used as 'drop in' to existing transportation infrastructure as alkanes are important components of gasoline and jet fuels. Despite the reported microbial production of alkanes, the toxicity of alkanes to microbial hosts could pose a bottleneck for high productivity. In this study, we aimed to improve the tolerance of Saccharomyces cerevisiae, a model eukaryotic host of industrial significance, to alkane biofuels. RESULTS To increase alkane tolerance in S. cerevisiae, we sought to exploit the pleiotropic drug resistance (Pdr) transcription factors Pdr1p and Pdr3p, which are master regulators of genes with pleiotropic drug resistance elements (PDREs)-containing upstream sequences. Wild-type and site-mutated Pdr1p and Pdr3p were expressed in S. cerevisiae BY4741 pdr1Δ pdr3Δ (BYL13). The point mutations of PDR1 (F815S) and PDR3 (Y276H) in BYL13 resulted in the highest tolerance to C10 alkane, and the expression of wild-type PDR3 in BYL13 led to the highest tolerance to C11 alkane. To identify and verify the correlation between the Pdr transcription factors and tolerance improvement, we analyzed the expression patterns of genes regulated by the Pdr transcription factors in the most tolerant strains against C10 and C11 alkanes. Quantitative PCR results showed that the Pdr transcription factors differentially regulated genes associated with multi-drug resistance, stress responses, and membrane modifications, suggesting different extents of intracellular alkane levels, reactive oxygen species (ROS) production and membrane integrity. We further showed that (i) the expression of Pdr1mt1 + Pdr3mt reduced intracellular C10 alkane by 67 % and ROS by 53 %, and significantly alleviated membrane damage; and (ii) the expression of the Pdr3wt reduced intracellular C11 alkane by 72 % and ROS by 21 %. Alkane transport assays also revealed that the reduction of alkane accumulation was due to higher export (C10 and C11 alkanes) and lower import (C11 alkane). CONCLUSIONS We improved yeast's tolerance to alkane biofuels by modulating the expression of the wild-type and site-mutated Pdr1p and Pdr3p, and extensively identified the correlation between Pdr transcription factors and tolerance improvement by analyzing gene patterns, alkane transport, ROS, and membrane integrity. These findings provide valuable insights into manipulating transcription factors in yeast for improved alkane tolerance and productivity.
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Affiliation(s)
- Hua Ling
- />Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore, Singapore
- />NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore, Singapore
| | - Nina Kurniasih Pratomo Juwono
- />Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore, Singapore
- />NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore, Singapore
| | - Wei Suong Teo
- />Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore, Singapore
- />NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore, Singapore
| | - Ruirui Liu
- />Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore, Singapore
- />NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore, Singapore
| | - Susanna Su Jan Leong
- />Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore, Singapore
- />NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore, Singapore
- />Singapore Institute of Technology, 10 Dover Drive, 138683 Singapore, Singapore
| | - Matthew Wook Chang
- />Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597 Singapore, Singapore
- />NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), Life Sciences Institute, National University of Singapore, 28 Medical Drive, 117456 Singapore, Singapore
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Muschiol J, Peters C, Oberleitner N, Mihovilovic MD, Bornscheuer UT, Rudroff F. Cascade catalysis – strategies and challenges en route to preparative synthetic biology. Chem Commun (Camb) 2015; 51:5798-811. [DOI: 10.1039/c4cc08752f] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this feature article recent progress and future perspectives of cascade catalysis combining bio/bio or bio/chemo catalysts are presented.
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Affiliation(s)
- Jan Muschiol
- Institute of Biochemistry
- Dept. of Biotechnology & Enzyme Catalysis
- Greifswald University
- 17489 Greifswald
- Germany
| | - Christin Peters
- Institute of Biochemistry
- Dept. of Biotechnology & Enzyme Catalysis
- Greifswald University
- 17489 Greifswald
- Germany
| | - Nikolin Oberleitner
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- 1060 Vienna
- Austria
| | - Marko D. Mihovilovic
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- 1060 Vienna
- Austria
| | - Uwe T. Bornscheuer
- Institute of Biochemistry
- Dept. of Biotechnology & Enzyme Catalysis
- Greifswald University
- 17489 Greifswald
- Germany
| | - Florian Rudroff
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- 1060 Vienna
- Austria
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213
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Metabolic engineering of Saccharomyces cerevisiae to improve 1-hexadecanol production. Metab Eng 2015; 27:10-19. [DOI: 10.1016/j.ymben.2014.10.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 08/06/2014] [Accepted: 10/14/2014] [Indexed: 01/09/2023]
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214
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Yan J, Liu Y, Wang C, Han B, Li S. Assembly of lipase and P450 fatty acid decarboxylase to constitute a novel biosynthetic pathway for production of 1-alkenes from renewable triacylglycerols and oils. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:34. [PMID: 25763106 PMCID: PMC4355466 DOI: 10.1186/s13068-015-0219-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 02/04/2015] [Indexed: 05/21/2023]
Abstract
BACKGROUND Biogenic hydrocarbons (biohydrocarbons) are broadly accepted to be the ideal 'drop-in' biofuel alternative to petroleum-based fuels due to their highly similar chemical composition and physical characteristics. The biological production of aliphatic hydrocarbons is largely dependent on engineering of the complicated enzymatic network surrounding fatty acid biosynthesis. RESULT In this work, we developed a novel system for bioproduction of terminal fatty alkenes (1-alkenes) from renewable and low-cost triacylglycerols (TAGs) based on the lipase hydrolysis coupled to the P450 catalyzed decarboxylation. This artificial biosynthetic pathway was constituted using both cell-free systems including purified enzymes or cell-free extracts, and cell-based systems including mixed resting cells or growing cells. The issues of high cost of fatty acid feedstock and complicated biosynthesis network were addressed by replacement of the de novo biosynthesized fatty acids with the fed cheap TAGs. This recombinant tandem enzymatic pathway consisting of the Thermomyces lanuginosus lipase (Tll) and the P450 fatty acid decarboxylase OleTJE resulted in the production of 1-alkenes from purified TAGs or natural oils with 6.7 to 46.0% yields. CONCLUSION Since this novel hydrocarbon-producing pathway only requires two catalytically efficient enzymatic steps, it may hold great potential for industrial application by fulfilling the large-scale and cost-effective conversion of renewable TAGs into biohydrocarbons. This work highlights the power of designing and implementing an artificial pathway for production of advanced biofuels.
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Affiliation(s)
- Jinyong Yan
- />Key Laboratory of Biofuels, and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, 266101 Qingdao, Shandong China
| | - Yi Liu
- />Key Laboratory of Biofuels, and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, 266101 Qingdao, Shandong China
- />University of Chinese Academy of Sciences, No. 19A Yuquan Road, 100049 Beijing, China
| | - Cong Wang
- />Key Laboratory of Biofuels, and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, 266101 Qingdao, Shandong China
| | - Bingnan Han
- />Key Laboratory for Marine Drugs, Department of Pharmacy, Renji Hospital, Shanghai Jiao Tong University School of Medicine, No. 145 Shandongzhong Road, 200127 Shanghai, China
| | - Shengying Li
- />Key Laboratory of Biofuels, and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, 266101 Qingdao, Shandong China
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Comba S, Sabatini M, Menendez-Bravo S, Arabolaza A, Gramajo H. Engineering a Streptomyces coelicolor biosynthesis pathway into Escherichia coli for high yield triglyceride production. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:172. [PMID: 25593590 PMCID: PMC4295399 DOI: 10.1186/s13068-014-0172-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/18/2014] [Indexed: 05/24/2023]
Abstract
BACKGROUND Microbial lipid production represents a potential alternative feedstock for the biofuel and oleochemical industries. Since Escherichia coli exhibits many genetic, technical, and biotechnological advantages over native oleaginous bacteria, we aimed to construct a metabolically engineered E. coli strain capable of accumulating high levels of triacylglycerol (TAG) and evaluate its neutral lipid productivity during high cell density fed-batch fermentations. RESULTS The Streptomyces coelicolor TAG biosynthesis pathway, defined by the acyl-CoA:diacylglycerol acyltransferase (DGAT) Sco0958 and the phosphatidic acid phosphatase (PAP) Lppβ, was successfully reconstructed in an E. coli diacylglycerol kinase (dgkA) mutant strain. TAG production in this genetic background was optimized by increasing the levels of the TAG precursors, diacylglycerol and long-chain acyl-CoAs. For this we carried out a series of stepwise optimizations of the chassis by 1) fine-tuning the expression of the heterologous SCO0958 and lppβ genes, 2) overexpression of the S. coelicolor acetyl-CoA carboxylase complex, and 3) mutation of fadE, the gene encoding for the acyl-CoA dehydrogenase that catalyzes the first step of the β-oxidation cycle in E. coli. The best producing strain, MPS13/pET28-0958-ACC/pBAD-LPPβ rendered a cellular content of 4.85% cell dry weight (CDW) TAG in batch cultivation. Process optimization of fed-batch fermentation in a 1-L stirred-tank bioreactor resulted in cultures with an OD600nm of 80 and a product titer of 722.1 mg TAG L(-1) at the end of the process. CONCLUSIONS This study represents the highest reported fed-batch productivity of TAG reached by a model non-oleaginous bacterium. The organism used as a platform was an E. coli BL21 derivative strain containing a deletion in the dgkA gene and containing the TAG biosynthesis genes from S. coelicolor. The genetic studies carried out with this strain indicate that diacylglycerol (DAG) availability appears to be one of the main limiting factors to achieve higher yields of the storage compound. Therefore, in order to develop a competitive process for neutral lipid production in E. coli, it is still necessary to better understand the native regulation of the carbon flow metabolism of this organism, and in particular, to improve the levels of DAG biosynthesis.
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Affiliation(s)
- Santiago Comba
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda (2000), Rosario, Argentina
| | - Martín Sabatini
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda (2000), Rosario, Argentina
| | - Simón Menendez-Bravo
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda (2000), Rosario, Argentina
| | - Ana Arabolaza
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda (2000), Rosario, Argentina
| | - Hugo Gramajo
- Microbiology Division, IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda (2000), Rosario, Argentina
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Rahman Z, Sung BH, Yi JY, Bui LM, Lee JH, Kim SC. Enhanced production of n-alkanes in Escherichia coli by spatial organization of biosynthetic pathway enzymes. J Biotechnol 2014; 192 Pt A:187-91. [DOI: 10.1016/j.jbiotec.2014.10.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/10/2014] [Accepted: 10/13/2014] [Indexed: 11/28/2022]
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218
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Akhtar MK, Dandapani H, Thiel K, Jones PR. Microbial production of 1-octanol: A naturally excreted biofuel with diesel-like properties. Metab Eng Commun 2014; 2:1-5. [PMID: 27066394 PMCID: PMC4802428 DOI: 10.1016/j.meteno.2014.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/09/2014] [Accepted: 11/03/2014] [Indexed: 11/29/2022] Open
Abstract
The development of sustainable, bio-based technologies to convert solar energy and carbon dioxide into fuels is a grand challenge. A core part of this challenge is to produce a fuel that is compatible with the existing transportation infrastructure. This task is further compounded by the commercial desire to separate the fuel from the biotechnological host. Based on its fuel characteristics, 1-octanol was identified as an attractive metabolic target with diesel-like properties. We therefore engineered a synthetic pathway specifically for the biosynthesis of 1-octanol in Escherichia coli BL21(DE3) by over-expression of three enzymes (thioesterase, carboxylic acid reductase and aldehyde reductase) and one maturation factor (phosphopantetheinyl transferase). Induction of this pathway in a shake flask resulted in 4.4 mg 1-octanol L-1 h-1 which exceeded the productivity of previously engineered strains. Furthermore, the majority (73%) of the fatty alcohol was localised within the media without the addition of detergent or solvent overlay. The deletion of acrA reduced the production and excretion of 1-octanol by 3-fold relative to the wild-type, suggesting that the AcrAB-TolC complex may be responsible for the majority of product efflux. This study presents 1-octanol as a potential fuel target that can be synthesised and naturally accumulated within the media using engineered microbes.
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Affiliation(s)
- M Kalim Akhtar
- Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland; Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Hariharan Dandapani
- Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland
| | - Kati Thiel
- Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland
| | - Patrik R Jones
- Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland; Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
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Retro-biosynthetic screening of a modular pathway design achieves selective route for microbial synthesis of 4-methyl-pentanol. Nat Commun 2014; 5:5031. [PMID: 25248664 DOI: 10.1038/ncomms6031] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 08/19/2014] [Indexed: 12/20/2022] Open
Abstract
Increasingly complex metabolic pathways have been engineered by modifying natural pathways and establishing de novo pathways with enzymes from a variety of organisms. Here we apply retro-biosynthetic screening to a modular pathway design to identify a redox neutral, theoretically high yielding route to a branched C6 alcohol. Enzymes capable of converting natural E. coli metabolites into 4-methyl-pentanol (4MP) via coenzyme A (CoA)-dependent chemistry were taken from nine different organisms to form a ten-step de novo pathway. Selectivity for 4MP is enhanced through the use of key enzymes acting on acyl-CoA intermediates, a carboxylic acid reductase from Nocardia iowensis and an alcohol dehydrogenase from Leifsonia sp. strain S749. One implementation of the full pathway from glucose demonstrates selective carbon chain extension and acid reduction with 4MP constituting 81% (90±7 mg l(-1)) of the observed alcohol products. The highest observed 4MP titre is 192±23 mg l(-1). These results demonstrate the ability of modular pathway screening to facilitate de novo pathway engineering.
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220
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Abstract
Due to the increasing concerns about limited fossil resources and environmental problems, there has been much interest in developing biofuels from renewable biomass. Ethanol is currently used as a major biofuel, as it can be easily produced by existing fermentation technology, but it is not the best biofuel due to its low energy density, high vapor pressure, hygroscopy, and incompatibility with current infrastructure. Higher alcohols, including 1-propanol, 1-butanol, isobutanol, 2-methyl-1-butanol, and 3-methyl-1-butanol, which possess fuel properties more similar to those of petroleum-based fuel, have attracted particular interest as alternatives to ethanol. Since microorganisms isolated from nature do not allow production of these alcohols at high enough efficiencies, metabolic engineering has been employed to enhance their production. Here, we review recent advances in metabolic engineering of microorganisms for the production of higher alcohols.
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221
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Kallio P, Pásztor A, Thiel K, Akhtar MK, Jones PR. An engineered pathway for the biosynthesis of renewable propane. Nat Commun 2014; 5:4731. [PMID: 25181600 PMCID: PMC4164768 DOI: 10.1038/ncomms5731] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 07/17/2014] [Indexed: 12/24/2022] Open
Abstract
The deployment of next-generation renewable biofuels can be enhanced by improving their compatibility with the current infrastructure for transportation, storage and utilization. Propane, the bulk component of liquid petroleum gas, is an appealing target as it already has a global market. In addition, it is a gas under standard conditions, but can easily be liquefied. This allows the fuel to immediately separate from the biocatalytic process after synthesis, yet does not preclude energy-dense storage as a liquid. Here we report, for the first time, a synthetic metabolic pathway for producing renewable propane. The pathway is based on a thioesterase specific for butyryl-acyl carrier protein (ACP), which allows native fatty acid biosynthesis of the Escherichia coli host to be redirected towards a synthetic alkane pathway. Propane biosynthesis is markedly stimulated by the introduction of an electron-donating module, optimizing the balance of O2 supply and removal of native aldehyde reductases. Propane is the main component of liquid petroleum gas and has a wide variety of commercial applications. Here, the authors engineer a synthetic metabolic pathway in E. coli, and demonstrate for the first time the renewable production of propane.
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Affiliation(s)
- Pauli Kallio
- 1] Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland [2]
| | - András Pásztor
- 1] Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland [2]
| | - Kati Thiel
- Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland
| | - M Kalim Akhtar
- 1] Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland [2]
| | - Patrik R Jones
- 1] Department of Biochemistry, University of Turku, Tykistökatu 6B 4krs, 20520 Turku, Finland [2] Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
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222
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Nozzi NE, Desai SH, Case AE, Atsumi S. Metabolic engineering for higher alcohol production. Metab Eng 2014; 25:174-82. [DOI: 10.1016/j.ymben.2014.07.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/16/2014] [Accepted: 07/16/2014] [Indexed: 10/25/2022]
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223
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Zhou YJ, Buijs NA, Siewers V, Nielsen J. Fatty Acid-Derived Biofuels and Chemicals Production in Saccharomyces cerevisiae. Front Bioeng Biotechnol 2014; 2:32. [PMID: 25225637 PMCID: PMC4150446 DOI: 10.3389/fbioe.2014.00032] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 08/18/2014] [Indexed: 11/28/2022] Open
Abstract
Volatile energy costs and environmental concerns have spurred interest in the development of alternative, renewable, sustainable, and cost-effective energy resources. Environment-friendly processes involving microbes can be used to synthesize advanced biofuels. These fuels have the potential to replace fossil fuels in supporting high-power demanding machinery such as aircrafts and trucks. From an engineering perspective, the pathway for fatty acid biosynthesis is an attractive route for the production of advanced fuels such as fatty acid ethyl esters, fatty alcohols, and alkanes. The robustness and excellent accessibility to molecular genetics make the yeast Saccharomyces cerevisiae a suitable host for the purpose of bio-manufacturing. Recent advances in metabolic engineering, as well as systems and synthetic biology, have now provided the opportunity to engineer yeast metabolism for the production of fatty acid-derived fuels and chemicals.
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Affiliation(s)
- Yongjin J. Zhou
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Nicolaas A. Buijs
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Verena Siewers
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Jens Nielsen
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
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224
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Akhtar MK, Jones PR. Cofactor engineering for enhancing the flux of metabolic pathways. Front Bioeng Biotechnol 2014; 2:30. [PMID: 25221776 PMCID: PMC4147997 DOI: 10.3389/fbioe.2014.00030] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 08/12/2014] [Indexed: 11/24/2022] Open
Abstract
The manufacture of a diverse array of chemicals is now possible with biologically engineered strains, an approach that is greatly facilitated by the emergence of synthetic biology. This is principally achieved through pathway engineering in which enzyme activities are coordinated within a genetically amenable host to generate the product of interest. A great deal of attention is typically given to the quantitative levels of the enzymes with little regard to their overall qualitative states. This highly constrained approach fails to consider other factors that may be necessary for enzyme functionality. In particular, enzymes with physically bound cofactors, otherwise known as holoenzymes, require careful evaluation. Herein, we discuss the importance of cofactors for biocatalytic processes and show with empirical examples why the synthesis and integration of cofactors for the formation of holoenzymes warrant a great deal of attention within the context of pathway engineering.
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Affiliation(s)
- M Kalim Akhtar
- Department of Biochemical Engineering, University College London , London , UK
| | - Patrik R Jones
- Department of Life Sciences, Imperial College London , London , UK
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225
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Pásztor A, Kallio P, Malatinszky D, Akhtar MK, Jones PR. A synthetic O2-tolerant butanol pathway exploiting native fatty acid biosynthesis inEscherichia coli. Biotechnol Bioeng 2014; 112:120-8. [DOI: 10.1002/bit.25324] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 06/23/2014] [Accepted: 06/25/2014] [Indexed: 11/07/2022]
Affiliation(s)
- András Pásztor
- Department of Biochemistry; University of Turku; Tykistökatu 6B 4krs 20520 Turku Finland
| | - Pauli Kallio
- Department of Biochemistry; University of Turku; Tykistökatu 6B 4krs 20520 Turku Finland
| | - Dávid Malatinszky
- Department of Life Sciences; Imperial College London; Sir Alexander Fleming Building London SW7 2AZ UK
| | - M. Kalim Akhtar
- Department of Biochemistry; University of Turku; Tykistökatu 6B 4krs 20520 Turku Finland
| | - Patrik R. Jones
- Department of Biochemistry; University of Turku; Tykistökatu 6B 4krs 20520 Turku Finland
- Department of Life Sciences; Imperial College London; Sir Alexander Fleming Building London SW7 2AZ UK
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226
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Kunjapur AM, Tarasova Y, Prather KLJ. Synthesis and accumulation of aromatic aldehydes in an engineered strain of Escherichia coli. J Am Chem Soc 2014; 136:11644-54. [PMID: 25076127 DOI: 10.1021/ja506664a] [Citation(s) in RCA: 190] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Aromatic aldehydes are useful in numerous applications, especially as flavors, fragrances, and pharmaceutical precursors. However, microbial synthesis of aldehydes is hindered by rapid, endogenous, and redundant conversion of aldehydes to their corresponding alcohols. We report the construction of an Escherichia coli K-12 MG1655 strain with reduced aromatic aldehyde reduction (RARE) that serves as a platform for aromatic aldehyde biosynthesis. Six genes with reported activity on the model substrate benzaldehyde were rationally targeted for deletion: three genes that encode aldo-keto reductases and three genes that encode alcohol dehydrogenases. Upon expression of a recombinant carboxylic acid reductase in the RARE strain and addition of benzoate during growth, benzaldehyde remained in the culture after 24 h, with less than 12% conversion of benzaldehyde to benzyl alcohol. Although individual overexpression results demonstrated that all six genes could contribute to benzaldehyde reduction in vivo, additional experiments featuring subset deletion strains revealed that two of the gene deletions were dispensable under the conditions tested. The engineered strain was next investigated for the production of vanillin from vanillate and succeeded in preventing formation of the byproduct vanillyl alcohol. A pathway for the biosynthesis of vanillin directly from glucose was introduced and resulted in a 55-fold improvement in vanillin titer when using the RARE strain versus the wild-type strain. Finally, synthesis of the chiral pharmaceutical intermediate L-phenylacetylcarbinol (L-PAC) was demonstrated from benzaldehyde and glucose upon expression of a recombinant mutant pyruvate decarboxylase in the RARE strain. Beyond allowing accumulation of aromatic aldehydes as end products in E. coli, the RARE strain expands the classes of chemicals that can be produced microbially via aldehyde intermediates.
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Affiliation(s)
- Aditya M Kunjapur
- Department of Chemical Engineering, ‡Synthetic Biology Engineering Research Center (SynBERC), §Microbiology Graduate Program, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Toward aldehyde and alkane production by removing aldehyde reductase activity in Escherichia coli. Metab Eng 2014; 25:227-37. [PMID: 25108218 DOI: 10.1016/j.ymben.2014.07.012] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 06/30/2014] [Accepted: 07/30/2014] [Indexed: 01/15/2023]
Abstract
Advances in synthetic biology and metabolic engineering have enabled the construction of novel biological routes to valuable chemicals using suitable microbial hosts. Aldehydes serve as chemical feedstocks in the synthesis of rubbers, plastics, and other larger molecules. Microbial production of alkanes is dependent on the formation of a fatty aldehyde intermediate which is converted to an alkane by an aldehyde deformylating oxygenase (ADO). However, microbial hosts such as Escherichia coli are plagued by many highly active endogenous aldehyde reductases (ALRs) that convert aldehydes to alcohols, which greatly complicates strain engineering for aldehyde and alkane production. It has been shown that the endogenous ALR activity outcompetes the ADO enzyme for fatty aldehyde substrate. The large degree of ALR redundancy coupled with an incomplete database of ALRs represents a significant obstacle in engineering E. coli for either aldehyde or alkane production. In this study, we identified 44 ALR candidates encoded in the E. coli genome using bioinformatics tools, and undertook a comprehensive screening by measuring the ability of these enzymes to produce isobutanol. From the pool of 44 candidates, we found five new ALRs using this screening method (YahK, DkgA, GldA, YbbO, and YghA). Combined deletions of all 13 known ALRs resulted in a 90-99% reduction in endogenous ALR activity for a wide range of aldehyde substrates (C2-C12). Elucidation of the ALRs found in E. coli could guide one in reducing competing alcohol formation during alkane or aldehyde production.
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228
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Menendez-Bravo S, Comba S, Sabatini M, Arabolaza A, Gramajo H. Expanding the chemical diversity of natural esters by engineering a polyketide-derived pathway into Escherichia coli. Metab Eng 2014; 24:97-106. [DOI: 10.1016/j.ymben.2014.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/29/2014] [Accepted: 05/05/2014] [Indexed: 01/25/2023]
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229
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Napora-Wijata K, Strohmeier GA, Winkler M. Biocatalytic reduction of carboxylic acids. Biotechnol J 2014; 9:822-43. [PMID: 24737783 DOI: 10.1002/biot.201400012] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 02/25/2014] [Accepted: 03/10/2014] [Indexed: 11/08/2022]
Abstract
An increasing demand for non-petroleum-based products is envisaged in the near future. Carboxylic acids such as citric acid, succinic acid, fatty acids, and many others are available in abundance from renewable resources and they could serve as economic precursors for bio-based products such as polymers, aldehyde building blocks, and alcohols. However, we are confronted with the problem that carboxylic acid reduction requires a high level of energy for activation due to the carboxylate's thermodynamic stability. Catalytic processes are scarce and often their chemoselectivity is insufficient. This review points at bio-alternatives: currently known enzyme classes and organisms that catalyze the reduction of carboxylic acids are summarized. Two totally distinct biocatalyst lines have evolved to catalyze the same reaction: aldehyde oxidoreductases from anaerobic bacteria and archea, and carboxylate reductases from aerobic sources such as bacteria, fungi, and plants. The majority of these enzymes remain to be identified and isolated from their natural background in order to evaluate their potential as industrial biocatalysts.
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230
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Santala S, Efimova E, Koskinen P, Karp MT, Santala V. Rewiring the wax ester production pathway of Acinetobacter baylyi ADP1. ACS Synth Biol 2014; 3:145-51. [PMID: 24898054 DOI: 10.1021/sb4000788] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Wax esters are industrially relevant high-value molecules. For sustainable production of wax esters, bacterial cell factories are suggested to replace the chemical processes exploiting expensive starting materials. However, it is well recognized that new sophisticated solutions employing synthetic biology toolbox are required to improve and tune the cellular production platform to meet the product requirements. For example, saturated wax esters with alkanol chain lengths C12 or C14 that are convenient for industrial uses are rare among bacteria. Acinetobacter baylyi ADP1, a natural producer of wax esters, is a convenient model organism for studying the potentiality and modifiability of wax esters in a natural host by means of synthetic biology. In order to establish a controllable production platform exploiting well-characterized biocomponents, and to modify the wax ester synthesis pathway of A. baylyi ADP1 in terms product quality, a fatty acid reductase complex LuxCDE with an inducible arabinose promoter was employed to replace the natural fatty acyl-CoA reductase acr1 in ADP1. The engineered strain was able to produce wax esters by the introduced synthetic pathway. Moreover, the fatty alkanol chain length profile of wax esters was found to shift toward shorter and more saturated carbon chains, C16:0 accounting for most of the alkanols. The study demonstrates the potentiality of recircuiting a biosynthesis pathway in a natural producer, enabling a regulated production of a customized bioproduct. Furthermore, the LuxCDE complex can be potentially used as a well-characterized biopart in a variety of synthetic biology applications involving the production of long-chain hydrocarbons.
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Affiliation(s)
- Suvi Santala
- Department
of Chemistry and Bioengineering, Tampere University of Technology, Tampere 33101, Finland
| | - Elena Efimova
- Department
of Chemistry and Bioengineering, Tampere University of Technology, Tampere 33101, Finland
| | - Perttu Koskinen
- Research and Development, Neste Oil Corporation, Porvoo 06101, Finland
| | - Matti Tapani Karp
- Department
of Chemistry and Bioengineering, Tampere University of Technology, Tampere 33101, Finland
| | - Ville Santala
- Department
of Chemistry and Bioengineering, Tampere University of Technology, Tampere 33101, Finland
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231
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Liu Y, Wang C, Yan J, Zhang W, Guan W, Lu X, Li S. Hydrogen peroxide-independent production of α-alkenes by OleTJE P450 fatty acid decarboxylase. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:28. [PMID: 24565055 PMCID: PMC3937522 DOI: 10.1186/1754-6834-7-28] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 02/10/2014] [Indexed: 05/21/2023]
Abstract
BACKGROUND Cytochrome P450 OleTJE from Jeotgalicoccus sp. ATCC 8456, a new member of the CYP152 peroxygenase family, was recently found to catalyze the unusual decarboxylation of long-chain fatty acids to form α-alkenes using H2O2 as the sole electron and oxygen donor. Because aliphatic α-alkenes are important chemicals that can be used as biofuels to replace fossil fuels, or for making lubricants, polymers and detergents, studies on OleTJE fatty acid decarboxylase are significant and may lead to commercial production of biogenic α-alkenes in the future, which are renewable and more environmentally friendly than petroleum-derived equivalents. RESULTS We report the H2O2-independent activity of OleTJE for the first time. In the presence of NADPH and O2, this P450 enzyme efficiently decarboxylates long-chain fatty acids (C12 to C20) in vitro when partnering with either the fused P450 reductase domain RhFRED from Rhodococcus sp. or the separate flavodoxin/flavodoxin reductase from Escherichia coli. In vivo, expression of OleTJE or OleTJE-RhFRED in different E. coli strains overproducing free fatty acids resulted in production of variant levels of multiple α-alkenes, with a highest total hydrocarbon titer of 97.6 mg·l-1. CONCLUSIONS The discovery of the H2O2-independent activity of OleTJE not only raises a number of fundamental questions on the monooxygenase-like mechanism of this peroxygenase, but also will direct the future metabolic engineering work toward improvement of O2/redox partner(s)/NADPH for overproduction of α-alkenes by OleTJE.
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Affiliation(s)
- Yi Liu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cong Wang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Jinyong Yan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Wei Zhang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Wenna Guan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Xuefeng Lu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
| | - Shengying Li
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, Shandong 266101, China
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232
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Fuchs G, Berg IA. Unfamiliar metabolic links in the central carbon metabolism. J Biotechnol 2014; 192 Pt B:314-22. [PMID: 24576434 DOI: 10.1016/j.jbiotec.2014.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/13/2014] [Accepted: 02/17/2014] [Indexed: 11/18/2022]
Abstract
The central carbon metabolism of all organisms is considered to follow a well established fixed scheme. However, recent studies of autotrophic carbon fixation in prokaryotes revealed unfamiliar metabolic links. A new route interconnects acetyl-coenzyme A (CoA) via 3-hydroxypropionate with succinyl-CoA. Succinyl-CoA in turn may be metabolized via 4-hydroxybutyrate to two molecules of acetyl-CoA; a reversal of this route would result in the assimilation of two molecules of acetyl-CoA into C4 compounds. C5-dicarboxylic acids are a rather neglected class of metabolites; yet, they play a key role not only in one of the CO2 fixation cycles, but also in two acetate assimilation pathways that replace the glyoxylate cycle. C5 compounds such as ethylmalonate, methylsuccinate, methylmalate, mesaconate, itaconate and citramalate or their CoA esters are thereby linked to the acetyl-CoA, propionyl-CoA, glyoxylate and pyruvate pools. A novel carboxylase/reductase converts crotonyl-CoA into ethylmalonyl-CoA; similar reductive carboxylations apply to other alpha-beta-unsaturated carboxy-CoA thioesters. These unfamiliar metabolic links may provide useful tools for metabolic engineering.
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Affiliation(s)
- Georg Fuchs
- Mikrobiologie, Fakultät für Biologie, Universität Freiburg, Schänzlestr. 1, D 79104 Freiburg, Germany.
| | - Ivan A Berg
- Mikrobiologie, Fakultät für Biologie, Universität Freiburg, Schänzlestr. 1, D 79104 Freiburg, Germany.
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233
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Napora-Wijata K, Robins K, Osorio-Lozada A, Winkler M. Whole-Cell Carboxylate Reduction for the Synthesis of 3-Hydroxytyrosol. ChemCatChem 2014. [DOI: 10.1002/cctc.201300913] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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234
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Janßen HJ, Steinbüchel A. Fatty acid synthesis in Escherichia coli and its applications towards the production of fatty acid based biofuels. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:7. [PMID: 24405789 PMCID: PMC3896788 DOI: 10.1186/1754-6834-7-7] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/24/2013] [Indexed: 05/04/2023]
Abstract
The idea of renewable and regenerative resources has inspired research for more than a hundred years. Ideally, the only spent energy will replenish itself, like plant material, sunlight, thermal energy or wind. Biodiesel or ethanol are examples, since their production relies mainly on plant material. However, it has become apparent that crop derived biofuels will not be sufficient to satisfy future energy demands. Thus, especially in the last decade a lot of research has focused on the production of next generation biofuels. A major subject of these investigations has been the microbial fatty acid biosynthesis with the aim to produce fatty acids or derivatives for substitution of diesel. As an industrially important organism and with the best studied microbial fatty acid biosynthesis, Escherichia coli has been chosen as producer in many of these studies and several reviews have been published in the fields of E. coli fatty acid biosynthesis or biofuels. However, most reviews discuss only one of these topics in detail, despite the fact, that a profound understanding of the involved enzymes and their regulation is necessary for efficient genetic engineering of the entire pathway. The first part of this review aims at summarizing the knowledge about fatty acid biosynthesis of E. coli and its regulation, and it provides the connection towards the production of fatty acids and related biofuels. The second part gives an overview about the achievements by genetic engineering of the fatty acid biosynthesis towards the production of next generation biofuels. Finally, the actual importance and potential of fatty acid-based biofuels will be discussed.
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Affiliation(s)
- Helge Jans Janßen
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, D-48149, Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 3, D-48149, Münster, Germany
- Environmental Sciences Department, King Abdulaziz University, Jeddah, Saudi Arabia
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Kuo J, Khosla C. The initiation ketosynthase (FabH) is the sole rate-limiting enzyme of the fatty acid synthase of Synechococcus sp. PCC 7002. Metab Eng 2014; 22:53-9. [PMID: 24395007 DOI: 10.1016/j.ymben.2013.12.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/28/2013] [Accepted: 12/24/2013] [Indexed: 12/22/2022]
Abstract
Cyanobacteria are Gram-negative bacteria that are desirable hosts for biodiesel production, because they are photosynthetic, relatively fast growing, and can secrete products. We have reconstituted the fatty acid synthase (FAS) of the cyanobacterium Synechococcus sp. PCC 7002 and subjected it to in vitro kinetic analysis. Our data revealed that the overall rate of this metabolic pathway is exclusively limited by the FabH ketosynthase, which initiates product synthesis by condensing malonyl-ACP with acetyl-CoA to form acetoacetyl-ACP. This finding sharply contrasts with our previous findings that the Escherichia coli FAS is predominantly limited by its dehydratase (FabZ) and enoyl reductase (FabI) activities and that FabH activity is not limiting. We therefore reconstituted and analyzed a set of "hybrid" FASs. When the Synechococcus FabH was used to replace its counterpart in the reconstituted E. coli FAS, the resulting synthase was strongly limited by FabH activity. Conversely, replacement of the E. coli FabZ with its Synechococcus homolog dramatically alleviated the dependence of E. coli FAS activity on FabZ. In agreement with this finding, introduction of the E. coli FabH in the Synechococcus FAS virtually eliminated its dependence on this subunit, whereas substitution of the Synechococcus FabZ with its E. coli homolog shifted a substantial fraction of the overall flux control in the Synechococcus FAS to FabZ. Our findings demonstrate that the rate-limiting steps can differ dramatically between closely related bacterial fatty acid synthases, and that such regulatory behavior is fundamentally the property of the controlling enzyme(s).
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Affiliation(s)
- James Kuo
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Chaitan Khosla
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA; Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
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236
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Beld J, Sonnenschein EC, Vickery CR, Noel JP, Burkart MD. The phosphopantetheinyl transferases: catalysis of a post-translational modification crucial for life. Nat Prod Rep 2014; 31:61-108. [PMID: 24292120 PMCID: PMC3918677 DOI: 10.1039/c3np70054b] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Covering: up to 2013. Although holo-acyl carrier protein synthase, AcpS, a phosphopantetheinyl transferase (PPTase), was characterized in the 1960s, it was not until the publication of the landmark paper by Lambalot et al. in 1996 that PPTases garnered wide-spread attention being classified as a distinct enzyme superfamily. In the past two decades an increasing number of papers have been published on PPTases ranging from identification, characterization, structure determination, mutagenesis, inhibition, and engineering in synthetic biology. In this review, we comprehensively discuss all current knowledge on this class of enzymes that post-translationally install a 4'-phosphopantetheine arm on various carrier proteins.
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Affiliation(s)
- Joris Beld
- Department of Chemistry and Biochemistry, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA.
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237
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Liu R, Zhu F, Lu L, Fu A, Lu J, Deng Z, Liu T. Metabolic engineering of fatty acyl-ACP reductase-dependent pathway to improve fatty alcohol production in Escherichia coli. Metab Eng 2013; 22:10-21. [PMID: 24333607 DOI: 10.1016/j.ymben.2013.12.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 11/14/2013] [Accepted: 12/03/2013] [Indexed: 12/24/2022]
Abstract
Fatty alcohols are important components of surfactants and cosmetic products. The production of fatty alcohols from sustainable resources using microbial fermentation could reduce dependence on fossil fuels and greenhouse gas emission. However, the industrialization of this process has been hampered by the current low yield and productivity of this synthetic pathway. As a result of metabolic engineering strategies, an Escherichia coli mutant containing Synechococcus elongatus fatty acyl-ACP reductase showed improved yield and productivity. Proteomics analysis and in vitro enzymatic assays showed that endogenous E. coli AdhP is a major contributor to the reduction of fatty aldehydes to fatty alcohols. Both in vitro and in vivo results clearly demonstrated that the activity and expression level of fatty acyl-CoA/ACP reductase is the rate-limiting step in the current protocol. In 2.5-L fed-batch fermentation with glycerol as the only carbon source, the most productive E. coli mutant produced 0.75 g/L fatty alcohols (0.02 g fatty alcohol/g glycerol) with a productivity of up to 0.06 g/L/h. This investigation establishes a promising synthetic pathway for industrial microbial production of fatty alcohols.
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Affiliation(s)
- Ran Liu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China; Wuhan J1 Biotech Co., Ltd., Wuhan 430075, China
| | - Fayin Zhu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China
| | - Lei Lu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China
| | - Aisi Fu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China
| | - Jiankai Lu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China; Hubei Engineering Laboratory for Synthetic Microbiology, Wuhan Institute of Biotechnology, Wuhan 430075, China
| | - Tiangang Liu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China; Hubei Engineering Laboratory for Synthetic Microbiology, Wuhan Institute of Biotechnology, Wuhan 430075, China.
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238
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Marsh ENG, Waugh MW. Aldehyde Decarbonylases: Enigmatic Enzymes of Hydrocarbon Biosynthesis. ACS Catal 2013; 3. [PMID: 24319622 DOI: 10.1021/cs400637t] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- E. Neil G. Marsh
- Department of Chemistry and ‡Department of
Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Matthew W. Waugh
- Department of Chemistry and ‡Department of
Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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239
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Pandelia ME, Li N, Nørgaard H, Warui DM, Rajakovich LJ, Chang WC, Booker SJ, Krebs C, Bollinger JM. Substrate-triggered addition of dioxygen to the diferrous cofactor of aldehyde-deformylating oxygenase to form a diferric-peroxide intermediate. J Am Chem Soc 2013; 135:15801-12. [PMID: 23987523 PMCID: PMC3869994 DOI: 10.1021/ja405047b] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cyanobacterial aldehyde-deformylating oxygenases (ADOs) belong to the ferritin-like diiron-carboxylate superfamily of dioxygen-activating proteins. They catalyze conversion of saturated or monounsaturated C(n) fatty aldehydes to formate and the corresponding C(n-1) alkanes or alkenes, respectively. This unusual, apparently redox-neutral transformation actually requires four electrons per turnover to reduce the O2 cosubstrate to the oxidation state of water and incorporates one O-atom from O2 into the formate coproduct. We show here that the complex of the diiron(II/II) form of ADO from Nostoc punctiforme (Np) with an aldehyde substrate reacts with O2 to form a colored intermediate with spectroscopic properties suggestive of a Fe2(III/III) complex with a bound peroxide. Its Mössbauer spectra reveal that the intermediate possesses an antiferromagnetically (AF) coupled Fe2(III/III) center with resolved subsites. The intermediate is long-lived in the absence of a reducing system, decaying slowly (t(1/2) ~ 400 s at 5 °C) to produce a very modest yield of formate (<0.15 enzyme equivalents), but reacts rapidly with the fully reduced form of 1-methoxy-5-methylphenazinium methylsulfate ((MeO)PMS) to yield product, albeit at only ~50% of the maximum theoretical yield (owing to competition from one or more unproductive pathway). The results represent the most definitive evidence to date that ADO can use a diiron cofactor (rather than a homo- or heterodinuclear cluster involving another transition metal) and provide support for a mechanism involving attack on the carbonyl of the bound substrate by the reduced O2 moiety to form a Fe2(III/III)-peroxyhemiacetal complex, which undergoes reductive O-O-bond cleavage, leading to C1-C2 radical fragmentation and formation of the alk(a/e)ne and formate products.
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Affiliation(s)
- Maria E. Pandelia
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ning Li
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Hanne Nørgaard
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Douglas M. Warui
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Lauren J. Rajakovich
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Wei-chen Chang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Squire J. Booker
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Carsten Krebs
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - J. Martin Bollinger
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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240
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Production of medium chain length fatty alcohols from glucose in Escherichia coli. Metab Eng 2013; 20:177-86. [PMID: 24141053 DOI: 10.1016/j.ymben.2013.10.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 09/19/2013] [Accepted: 10/11/2013] [Indexed: 12/20/2022]
Abstract
Metabolic engineering offers the opportunity to produce a wide range of commodity chemicals that are currently derived from petroleum or other non-renewable resources. Microbial synthesis of fatty alcohols is an attractive process because it can control the distribution of chain lengths and utilize low cost fermentation substrates. Specifically, primary alcohols with chain lengths of 12 to 14 carbons have many uses in the production of detergents, surfactants, and personal care products. The current challenge is to produce these compounds at titers and yields that would make them economically competitive. Here, we demonstrate a metabolic engineering strategy for producing fatty alcohols from glucose. To produce a high level of 1-dodecanol and 1-tetradecanol, an acyl-ACP thioesterase (BTE), an acyl-CoA ligase (FadD), and an acyl-CoA/aldehyde reductase (MAACR) were overexpressed in an engineered strain of Escherichia coli. Yields were improved by balancing expression levels of each gene, using a fed-batch cultivation strategy, and adding a solvent to the culture for extracting the product from cells. Using these strategies, a titer of over 1.6 g/L fatty alcohol with a yield of over 0.13 g fatty alcohol/g carbon source was achieved. These are the highest reported yield of fatty alcohols produced from glucose in E. coli.
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241
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Abstract
Alka(e)nes are the predominant constituents of gasoline, diesel, and jet fuels. They can be produced naturally by a wide range of microorganisms. Bio-alka(e)nes can be used as drop-in biofuels. To date, five microbial pathways that convert free fatty acids or fatty acid derivatives into alka(e)nes have been identified or reconstituted. The discoveries open a door to achieve microbial production of alka(e)nes with high efficiency. The modules derived from these alka(e)ne biosynthetic pathways can be assembled as biological parts and synthetic biology strategies can be employed to optimize the metabolic pathways and improve alka(e)ne production.
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Affiliation(s)
- Weihua Wang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China
| | - Xuefeng Lu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences , Qingdao , China
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242
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Kallio P, Pásztor A, Akhtar MK, Jones PR. Renewable jet fuel. Curr Opin Biotechnol 2013; 26:50-5. [PMID: 24679258 DOI: 10.1016/j.copbio.2013.09.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/10/2013] [Accepted: 09/11/2013] [Indexed: 11/25/2022]
Abstract
Novel strategies for sustainable replacement of finite fossil fuels are intensely pursued in fundamental research, applied science and industry. In the case of jet fuels used in gas-turbine engine aircrafts, the production and use of synthetic bio-derived kerosenes are advancing rapidly. Microbial biotechnology could potentially also be used to complement the renewable production of jet fuel, as demonstrated by the production of bioethanol and biodiesel for piston engine vehicles. Engineered microbial biosynthesis of medium chain length alkanes, which constitute the major fraction of petroleum-based jet fuels, was recently demonstrated. Although efficiencies currently are far from that needed for commercial application, this discovery has spurred research towards future production platforms using both fermentative and direct photobiological routes.
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Affiliation(s)
- Pauli Kallio
- Bioenergy Group, University of Turku, Tykistökatu 6A, 6krs, 20520 Turku, Finland
| | - András Pásztor
- Bioenergy Group, University of Turku, Tykistökatu 6A, 6krs, 20520 Turku, Finland
| | - M Kalim Akhtar
- Bioenergy Group, University of Turku, Tykistökatu 6A, 6krs, 20520 Turku, Finland
| | - Patrik R Jones
- Bioenergy Group, University of Turku, Tykistökatu 6A, 6krs, 20520 Turku, Finland.
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243
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Mattam AJ, Yazdani SS. Engineering E. coli strain for conversion of short chain fatty acids to bioalcohols. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:128. [PMID: 24020887 PMCID: PMC3847231 DOI: 10.1186/1754-6834-6-128] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/04/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Recent progress in production of various biofuel precursors and molecules, such as fatty acids, alcohols and alka(e)nes, is a significant step forward for replacing the fossil fuels with renewable fuels. A two-step process, where fatty acids from sugars are produced in the first step and then converted to corresponding biofuel molecules in the second step, seems more viable and attractive at this stage. We have engineered an Escherichia coli strain to take care of the second step for converting short chain fatty acids into corresponding alcohols by using butyrate kinase (Buk), phosphotransbutyrylase (Ptb) and aldehyde/alcohol dehydrogenase (AdhE2) from Clostridium acetobutylicum. RESULTS The engineered E. coli was able to convert butyric acid and other short chain fatty acids of chain length C3 to C7 into corresponding alcohols and the efficiency of conversion varied with different E. coli strain type. Glycerol proved to be a better donor of ATP and electron as compared to glucose for converting butyric acid to butanol. The engineered E. coli was able to tolerate up to 100 mM butyric acid and produced butanol with the conversion rate close to 100% under anaerobic condition. Deletion of native genes, such as fumarate reductase (frdA) and alcohol dehydrogenase (adhE), responsible for side products succinate and ethanol, which act as electron sink and could compete with butyric acid uptake, did not improve the butanol production efficiency. Indigenous acyl-CoA synthetase (fadD) was found to play no role in the conversion of butyric acid to butanol. Engineered E. coli was cultivated in a bioreactor under controlled condition where 60 mM butanol was produced within 24 h of cultivation. A continuous bioreactor with the provision of cell recycling allowed the continuous production of butanol at the average productivity of 7.6 mmol/l/h until 240 h. CONCLUSIONS E. coli engineered with the pathway from C. acetobutylicum could efficiently convert butyric acid to butanol. Other short chain fatty acids with the chain length of C3 to C7 were also converted to the corresponding alcohols. The ability of engineered strain to convert butyric acid to butanol continuously demonstrates commercial significance of the system.
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Affiliation(s)
- Anu Jose Mattam
- Synthetic Biology and Biofuels Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, 110067 New Delhi, India
| | - Syed Shams Yazdani
- Synthetic Biology and Biofuels Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, 110067 New Delhi, India
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244
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Chisti Y. Constraints to commercialization of algal fuels. J Biotechnol 2013; 167:201-14. [DOI: 10.1016/j.jbiotec.2013.07.020] [Citation(s) in RCA: 510] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/12/2013] [Accepted: 07/12/2013] [Indexed: 01/01/2023]
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245
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Straathof AJJ. Transformation of Biomass into Commodity Chemicals Using Enzymes or Cells. Chem Rev 2013; 114:1871-908. [DOI: 10.1021/cr400309c] [Citation(s) in RCA: 315] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Adrie J. J. Straathof
- Department of Biotechnology, Delft University of Technology, Julianalaan
67, 2628
BC Delft, The Netherlands
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246
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Synthesis of customized petroleum-replica fuel molecules by targeted modification of free fatty acid pools in Escherichia coli. Proc Natl Acad Sci U S A 2013; 110:7636-41. [PMID: 23610415 DOI: 10.1073/pnas.1215966110] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Biofuels are the most immediate, practical solution for mitigating dependence on fossil hydrocarbons, but current biofuels (alcohols and biodiesels) require significant downstream processing and are not fully compatible with modern, mass-market internal combustion engines. Rather, the ideal biofuels are structurally and chemically identical to the fossil fuels they seek to replace (i.e., aliphatic n- and iso-alkanes and -alkenes of various chain lengths). Here we report on production of such petroleum-replica hydrocarbons in Escherichia coli. The activity of the fatty acid (FA) reductase complex from Photorhabdus luminescens was coupled with aldehyde decarbonylase from Nostoc punctiforme to use free FAs as substrates for alkane biosynthesis. This combination of genes enabled rational alterations to hydrocarbon chain length (Cn) and the production of branched alkanes through upstream genetic and exogenous manipulations of the FA pool. Genetic components for targeted manipulation of the FA pool included expression of a thioesterase from Cinnamomum camphora (camphor) to alter alkane Cn and expression of the branched-chain α-keto acid dehydrogenase complex and β-keto acyl-acyl carrier protein synthase III from Bacillus subtilis to synthesize branched (iso-) alkanes. Rather than simply reconstituting existing metabolic routes to alkane production found in nature, these results demonstrate the ability to design and implement artificial molecular pathways for the production of renewable, industrially relevant fuel molecules.
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247
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Lennen RM, Pfleger BF. Microbial production of fatty acid-derived fuels and chemicals. Curr Opin Biotechnol 2013; 24:1044-53. [PMID: 23541503 DOI: 10.1016/j.copbio.2013.02.028] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 02/27/2013] [Accepted: 02/28/2013] [Indexed: 12/21/2022]
Abstract
Fatty acid metabolism is an attractive route to produce liquid transportation fuels and commodity oleochemicals from renewable feedstocks. Recently, genes and enzymes, which comprise metabolic pathways for producing fatty acid-derived compounds (e.g. esters, alkanes, olefins, ketones, alcohols, polyesters) have been elucidated and used in engineered microbial hosts. The resulting strains often generate products at low percentages of maximum theoretical yields, leaving significant room for metabolic engineering. Economically viable processes will require strains to approach theoretical yields, particularly for replacement of petroleum-derived fuels. This review will describe recent progress toward this goal, highlighting the scientific discoveries of each pathway, ongoing biochemical studies to understand each enzyme, and metabolic engineering strategies that are being used to improve strain performance.
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Affiliation(s)
- Rebecca M Lennen
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Room 3629, Madison, WI 53706, United States; U.S. Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, 1550 Linden Drive, Madison, WI 53706, United States
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