51
|
Wierzbicki M, Niraula N, Yarrabothula A, Layton DS, Trinh CT. Engineering an Escherichia coli platform to synthesize designer biodiesels. J Biotechnol 2016; 224:27-34. [DOI: 10.1016/j.jbiotec.2016.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 02/22/2016] [Accepted: 03/02/2016] [Indexed: 01/14/2023]
|
52
|
Liao JC, Mi L, Pontrelli S, Luo S. Fuelling the future: microbial engineering for the production of sustainable biofuels. Nat Rev Microbiol 2016; 14:288-304. [DOI: 10.1038/nrmicro.2016.32] [Citation(s) in RCA: 386] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
53
|
Abstract
A central challenge in the field of metabolic engineering is the efficient identification of a metabolic pathway genotype that maximizes specific productivity over a robust range of process conditions. Here we review current methods for optimizing specific productivity of metabolic pathways in living cells. New tools for library generation, computational analysis of pathway sequence-flux space, and high-throughput screening and selection techniques are discussed.
Collapse
Affiliation(s)
- Justin R Klesmith
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Timothy A Whitehead
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA; Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI 48824, USA
| |
Collapse
|
54
|
Sun X, Shen X, Jain R, Lin Y, Wang J, Sun J, Wang J, Yan Y, Yuan Q. Synthesis of chemicals by metabolic engineering of microbes. Chem Soc Rev 2016; 44:3760-85. [PMID: 25940754 DOI: 10.1039/c5cs00159e] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Metabolic engineering is a powerful tool for the sustainable production of chemicals. Over the years, the exploration of microbial, animal and plant metabolism has generated a wealth of valuable genetic information. The prudent application of this knowledge on cellular metabolism and biochemistry has enabled the construction of novel metabolic pathways that do not exist in nature or enhance existing ones. The hand in hand development of computational technology, protein science and genetic manipulation tools has formed the basis of powerful emerging technologies that make the production of green chemicals and fuels a reality. Microbial production of chemicals is more feasible compared to plant and animal systems, due to simpler genetic make-up and amenable growth rates. Here, we summarize the recent progress in the synthesis of biofuels, value added chemicals, pharmaceuticals and nutraceuticals via metabolic engineering of microbes.
Collapse
Affiliation(s)
- Xinxiao Sun
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15#, Beisanhuan East Road, Chaoyang District, Beijing 100029, China.
| | | | | | | | | | | | | | | | | |
Collapse
|
55
|
Escherichia coli enoyl-acyl carrier protein reductase (FabI) supports efficient operation of a functional reversal of β-oxidation cycle. Appl Environ Microbiol 2016; 81:1406-16. [PMID: 25527535 DOI: 10.1128/aem.03521-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We recently used a synthetic/bottom-up approach to establish the identity of the four enzymes composing an engineered functional reversal of the -oxidation cycle for fuel and chemical production in Escherichia coli (J. M. Clomburg, J. E. Vick, M. D. Blankschien, M. Rodriguez-Moya, and R. Gonzalez, ACS Synth Biol 1:541–554, 2012, http://dx.doi.org/10.1021/sb3000782).While native enzymes that catalyze the first three steps of the pathway were identified, the identity of the native enzyme(s) acting as the trans-enoyl coenzyme A (CoA) reductase(s) remained unknown, limiting the amount of product that could be synthesized (e.g., 0.34 g/liter butyrate) and requiring the overexpression of a foreign enzyme (the Euglena gracilis trans-enoyl-CoA reductase [EgTER]) to achieve high titers (e.g., 3.4 g/liter butyrate). Here, we examine several native E. coli enzymes hypothesized to catalyze the reduction of enoyl-CoAs to acyl-CoAs. Our results indicate that FabI, the native enoyl-acyl carrier protein (enoyl-ACP) reductase (ENR) from type II fatty acid biosynthesis, possesses sufficient NADH-dependent TER activity to support the efficient operation of a -oxidation reversal. Overexpression of FabI proved as effective as EgTER for the production of butyrate and longer-chain carboxylic acids. Given the essential nature of fabI, we investigated whether bacterial ENRs from other families were able to complement a fabI deletion without promiscuous reduction of crotonyl-CoA. These characteristics from Bacillus subtilis FabL enabled deltaffabI complementation experiments that conclusively established that FabI encodes a native enoyl-CoA reductase activity that supports the β-oxidation reversal in E. coli.
Collapse
|
56
|
Sheppard MJ, Kunjapur AM, Prather KL. Modular and selective biosynthesis of gasoline-range alkanes. Metab Eng 2016; 33:28-40. [DOI: 10.1016/j.ymben.2015.10.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 07/27/2015] [Accepted: 10/27/2015] [Indexed: 12/16/2022]
|
57
|
Boock JT, Gupta A, Prather KLJ. Screening and modular design for metabolic pathway optimization. Curr Opin Biotechnol 2015; 36:189-98. [DOI: 10.1016/j.copbio.2015.08.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/07/2015] [Accepted: 08/10/2015] [Indexed: 11/26/2022]
|
58
|
Kang A, Lee TS. Converting Sugars to Biofuels: Ethanol and Beyond. Bioengineering (Basel) 2015; 2:184-203. [PMID: 28952477 PMCID: PMC5597089 DOI: 10.3390/bioengineering2040184] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/15/2015] [Accepted: 10/20/2015] [Indexed: 11/16/2022] Open
Abstract
To date, the most significant sources of biofuels are starch- or sugarcane-based ethanol, which have been industrially produced in large quantities in the USA and Brazil, respectively. However, the ultimate goal of biofuel production is to produce fuels from lignocellulosic biomass-derived sugars with optimal fuel properties and compatibility with the existing fuel distribution infrastructure. To achieve this goal, metabolic pathways have been constructed to produce various fuel molecules that are categorized into fermentative alcohols (butanol and isobutanol), non-fermentative alcohols from 2-keto acid pathways, fatty acids-derived fuels and isoprenoid-derived fuels. This review will focus on current metabolic engineering efforts to improve the productivity and the yield of several key biofuel molecules. Strategies used in these metabolic engineering efforts can be summarized as follows: (1) identification of better enzymes; (2) flux control of intermediates and precursors; (3) elimination of competing pathways; (4) redox balance and cofactor regeneration; and (5) bypassing regulatory mechanisms. In addition to metabolic engineering approaches, host strains are optimized by improving sugar uptake and utilization, and increasing tolerance to toxic hydrolysates, metabolic intermediates and/or biofuel products.
Collapse
Affiliation(s)
- Aram Kang
- Joint BioEnergy Institute, Emeryville, CA 94608, USA.
- Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Taek Soon Lee
- Joint BioEnergy Institute, Emeryville, CA 94608, USA.
- Biological Systems & Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| |
Collapse
|
59
|
Christen M, Deutsch S, Christen B. Genome Calligrapher: A Web Tool for Refactoring Bacterial Genome Sequences for de Novo DNA Synthesis. ACS Synth Biol 2015; 4:927-34. [PMID: 26107775 DOI: 10.1021/acssynbio.5b00087] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent advances in synthetic biology have resulted in an increasing demand for the de novo synthesis of large-scale DNA constructs. Any process improvement that enables fast and cost-effective streamlining of digitized genetic information into fabricable DNA sequences holds great promise to study, mine, and engineer genomes. Here, we present Genome Calligrapher, a computer-aided design web tool intended for whole genome refactoring of bacterial chromosomes for de novo DNA synthesis. By applying a neutral recoding algorithm, Genome Calligrapher optimizes GC content and removes obstructive DNA features known to interfere with the synthesis of double-stranded DNA and the higher order assembly into large DNA constructs. Subsequent bioinformatics analysis revealed that synthesis constraints are prevalent among bacterial genomes. However, a low level of codon replacement is sufficient for refactoring bacterial genomes into easy-to-synthesize DNA sequences. To test the algorithm, 168 kb of synthetic DNA comprising approximately 20 percent of the synthetic essential genome of the cell-cycle bacterium Caulobacter crescentus was streamlined and then ordered from a commercial supplier of low-cost de novo DNA synthesis. The successful assembly into eight 20 kb segments indicates that Genome Calligrapher algorithm can be efficiently used to refactor difficult-to-synthesize DNA. Genome Calligrapher is broadly applicable to recode biosynthetic pathways, DNA sequences, and whole bacterial genomes, thus offering new opportunities to use synthetic biology tools to explore the functionality of microbial diversity. The Genome Calligrapher web tool can be accessed at https://christenlab.ethz.ch/GenomeCalligrapher .
Collapse
Affiliation(s)
- Matthias Christen
- Institute
of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8093 Zürich, Switzerland
| | - Samuel Deutsch
- Joint Genome Institute, Walnut Creek, California 94598, United States
| | - Beat Christen
- Institute
of Molecular Systems Biology, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8093 Zürich, Switzerland
| |
Collapse
|
60
|
Activity of Lactobacillus brevis Alcohol Dehydrogenase on Primary and Secondary Alcohol Biofuel Precursors. FERMENTATION-BASEL 2015. [DOI: 10.3390/fermentation1010024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
61
|
Mukhopadhyay A. Tolerance engineering in bacteria for the production of advanced biofuels and chemicals. Trends Microbiol 2015; 23:498-508. [DOI: 10.1016/j.tim.2015.04.008] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 04/17/2015] [Accepted: 04/23/2015] [Indexed: 02/06/2023]
|
62
|
Bayer T, Milker S, Wiesinger T, Rudroff F, Mihovilovic MD. Designer Microorganisms for Optimized Redox Cascade Reactions - Challenges and Future Perspectives. Adv Synth Catal 2015. [DOI: 10.1002/adsc.201500202] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
63
|
Pfleger BF, Gossing M, Nielsen J. Metabolic engineering strategies for microbial synthesis of oleochemicals. Metab Eng 2015; 29:1-11. [PMID: 25662836 DOI: 10.1016/j.ymben.2015.01.009] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 11/30/2022]
Abstract
Microbial synthesis of oleochemicals has advanced significantly in the last decade. Microbes have been engineered to convert renewable substrates to a wide range of molecules that are ordinarily made from plant oils. This approach is attractive because it can reduce a motivation for converting tropical rainforest into farmland while simultaneously enabling access to molecules that are currently expensive to produce from oil crops. In the last decade, enzymes responsible for producing oleochemicals in nature have been identified, strategies to circumvent native regulation have been developed, and high yielding strains have been designed, built, and successfully demonstrated. This review will describe the metabolic pathways that lead to the diverse molecular features found in natural oleochemicals, highlight successful metabolic engineering strategies, and comment on areas where future work could further advance the field.
Collapse
Affiliation(s)
- Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI, United States; Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, United States.
| | - Michael Gossing
- Department of Biology and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden
| | - Jens Nielsen
- Department of Biology and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden
| |
Collapse
|
64
|
Liu P, Zhu X, Tan Z, Zhang X, Ma Y. Construction of Escherichia Coli Cell Factories for Production of Organic Acids and Alcohols. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015; 155:107-40. [PMID: 25577396 DOI: 10.1007/10_2014_294] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Production of bulk chemicals from renewable biomass has been proved to be sustainable and environmentally friendly. Escherichia coli is the most commonly used host strain for constructing cell factories for production of bulk chemicals since it has clear physiological and genetic characteristics, grows fast in minimal salts medium, uses a wide range of substrates, and can be genetically modified easily. With the development of metabolic engineering, systems biology, and synthetic biology, a technology platform has been established to construct E. coli cell factories for bulk chemicals production. In this chapter, we will introduce this technology platform, as well as E. coli cell factories successfully constructed for production of organic acids and alcohols.
Collapse
Affiliation(s)
- Pingping Liu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, 32 West 7th Ave, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Xinna Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, 32 West 7th Ave, Tianjin Airport Economic Area, Tianjin, 300308, China
| | - Zaigao Tan
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, 32 West 7th Ave, Tianjin Airport Economic Area, Tianjin, 300308, China.,University of Chinese Academy of Sciences, Tianjin, China
| | - Xueli Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China. .,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, 32 West 7th Ave, Tianjin Airport Economic Area, Tianjin, 300308, China.
| | - Yanhe Ma
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| |
Collapse
|
65
|
Yu AQ, Pratomo Juwono NK, Leong SSJ, Chang MW. Production of Fatty Acid-derived valuable chemicals in synthetic microbes. Front Bioeng Biotechnol 2014; 2:78. [PMID: 25566540 PMCID: PMC4275033 DOI: 10.3389/fbioe.2014.00078] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/10/2014] [Indexed: 12/18/2022] Open
Abstract
Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters, and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants, and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed: (i) the current status of metabolic engineering of microbes that produce fatty acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes.
Collapse
Affiliation(s)
- Ai-Qun Yu
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , Singapore ; Synthetic Biology Research Program, National University of Singapore , Singapore , Singapore
| | - Nina Kurniasih Pratomo Juwono
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , Singapore ; Synthetic Biology Research Program, National University of Singapore , Singapore , Singapore
| | - Susanna Su Jan Leong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , Singapore ; Synthetic Biology Research Program, National University of Singapore , Singapore , Singapore ; Singapore Institute of Technology , Singapore , Singapore
| | - Matthew Wook Chang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore , Singapore , Singapore ; Synthetic Biology Research Program, National University of Singapore , Singapore , Singapore
| |
Collapse
|
66
|
Tai YS, Xiong M, Zhang K. Engineered biosynthesis of medium-chain esters in Escherichia coli. Metab Eng 2014; 27:20-28. [PMID: 25447641 DOI: 10.1016/j.ymben.2014.10.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 09/28/2014] [Accepted: 10/20/2014] [Indexed: 01/17/2023]
Abstract
Medium-chain esters such as isobutyl acetate (IBAc) and isoamyl acetate (IAAc) are high-volume solvents, flavors and fragrances. In this work, we engineered synthetic metabolic pathways in Escherichia coli for the total biosynthesis of IBAc and IAAc directly from glucose. Our pathways harnessed the power of natural amino acid biosynthesis. In particular, the native valine and leucine pathways in E. coli were utilized to supply the precursors. Then alcohol acyltransferases from various organisms were investigated on their capability to catalyze esterification reactions. It was discovered that ATF1 from Saccharomyces cerevisiae was the best enzyme for the formation of both IBAc and IAAc in E. coli. In vitro biochemical characterization of ATF1 confirmed the fermentation results and provided rational guidance for future enzyme engineering. We also performed strain improvement by removing byproduct pathways (Δldh, ΔpoxB, Δpta) and increased the production of both target chemicals. Then the best IBAc producing strain was used for scale-up fermentation in a 1.3-L benchtop bioreactor. 36g/L of IBAc was produced after 72h fermentation. This work demonstrates the feasibility of total biosynthesis of medium-chain esters as renewable chemicals.
Collapse
Affiliation(s)
- Yi-Shu Tai
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mingyong Xiong
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kechun Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| |
Collapse
|
67
|
Layton DS, Trinh CT. Engineering modular ester fermentative pathways in Escherichia coli. Metab Eng 2014; 26:77-88. [PMID: 25281839 DOI: 10.1016/j.ymben.2014.09.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/30/2014] [Accepted: 09/24/2014] [Indexed: 01/09/2023]
Abstract
Sensation profiles are observed all around us and are made up of many different molecules, such as esters. These profiles can be mimicked in everyday items for their uses in foods, beverages, cosmetics, perfumes, solvents, and biofuels. Here, we developed a systematic 'natural' way to derive these products via fermentative biosynthesis. Each ester fermentative pathway was designed as an exchangeable ester production module for generating two precursors- alcohols and acyl-CoAs that were condensed by an alcohol acyltransferase to produce a combinatorial library of unique esters. As a proof-of-principle, we coupled these ester modules with an engineered, modular, Escherichia coli chassis in a plug-and-play fashion to create microbial cell factories for enhanced anaerobic production of a butyrate ester library. We demonstrated tight coupling between the modular chassis and ester modules for enhanced product biosynthesis, an engineered phenotype useful for directed metabolic pathway evolution. Compared to the wildtype, the engineered cell factories yielded up to 48 fold increase in butyrate ester production from glucose.
Collapse
Affiliation(s)
- Donovan S Layton
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, United States
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, United States.
| |
Collapse
|
68
|
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.
Collapse
|
69
|
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]
|
70
|
Dhamankar H, Tarasova Y, Martin CH, Prather KL. Engineering E. coli for the biosynthesis of 3-hydroxy-γ-butyrolactone (3HBL) and 3,4-dihydroxybutyric acid (3,4-DHBA) as value-added chemicals from glucose as a sole carbon source. Metab Eng 2014; 25:72-81. [DOI: 10.1016/j.ymben.2014.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 04/18/2014] [Accepted: 06/09/2014] [Indexed: 10/25/2022]
|
71
|
Engineering Escherichia coli for odd straight medium chain free fatty acid production. Appl Microbiol Biotechnol 2014; 98:8145-54. [PMID: 25030454 DOI: 10.1007/s00253-014-5882-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 06/03/2014] [Accepted: 06/11/2014] [Indexed: 01/25/2023]
Abstract
Microbial biosynthesis of free fatty acids (FFAs) can be achieved by introducing an acyl-acyl carrier protein thioesterase gene into Escherichia coli. The engineered E. coli usually produced even chain FFAs. In this study, propionyl-CoA synthetase (prpE) from Salmonella enterica was overexpressed in two efficient even chain FFAs producers, ML103 (pXZM12) carrying the acyl-ACP thioesterase gene from Umbellularia californica and ML103 (pXZ18) carrying the acyl-ACP thioesterase gene from Ricinus communis combined with supplement of extracellular propionate. With these metabolically engineered E. coli, the odd straight chain FFAs, undecanoic acid (C11:0), tridecanoic acid (C13:0), and pentadecanoic acid (C15:0) were produced from glucose and propionate. The highest total odd straight chain FFAs produced by ML103 (pXZM12, pBAD-prpE) reached 276 mg/l with a ratio of 23.43 % of the total FFAs. In ML103 (pXZ18, pBAD-prpE), the highest total odd straight chain FFAs accumulated to 297 mg/l, and the ratio reached 17.68 % of the total FFAs. Due to the different substrate specificity of the acyl-ACP thioesterases, the major odd straight chain FFA components of ML103 (pXZM12, pBAD-prpE) were undecanoic acid and tridecanoic acid, while the ML103 (pXZ18, pBAD-prpE) preferred pentadecanoic acid.
Collapse
|
72
|
Wu H, San KY. Efficient odd straight medium chain free fatty acid production by metabolically engineered Escherichia coli. Biotechnol Bioeng 2014; 111:2209-19. [PMID: 24889416 DOI: 10.1002/bit.25296] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 04/24/2014] [Accepted: 05/25/2014] [Indexed: 11/11/2022]
Abstract
Free fatty acids (FFAs) can be used as precursors for the production of biofuels or chemicals. Different composition of FFAs will be useful for further modification of the biofuel/biochemical quality. Microbial biosynthesis of even chain FFAs can be achieved by introducing an acyl-acyl carrier protein thioesterase gene into E. coli. In this study, odd straight medium chain FFAs production was investigated by using metabolic engineered E. coli carrying acyl-ACP thioesterase (TE, Ricinus communis), propionyl-CoA synthase (Salmonella enterica), and β-ketoacyl-acyl carrier protein synthase III (four different sources) with supplement of extracellular propionate. By using these metabolically engineered E. coli, significant quantity of C13 and C15 odd straight-chain FFAs could be produced from glucose and propionate. The highest concentration of total odd straight chain FFAs attained was 1205 mg/L by the strain HWK201 (pXZ18, pBHE2), and 85% of the odd straight chain FFAs was C15. However, the highest percentage of odd straight chain FFAs was achieved by the strain HWK201 (pXZ18, pBHE3) of 83.2% at 48 h. This strategy was also applied successfully in strains carrying different TE, such as the medium length acyl-ACP thioesterase gene from Umbellularia californica. C11 and C13 became the major odd straight-chain FFAs.
Collapse
Affiliation(s)
- Hui Wu
- Department of Bioengineering, Rice University, Houston, Texas
| | | |
Collapse
|
73
|
McKenna R, Moya L, McDaniel M, Nielsen DR. Comparing in situ removal strategies for improving styrene bioproduction. Bioprocess Biosyst Eng 2014; 38:165-74. [DOI: 10.1007/s00449-014-1255-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 07/06/2014] [Indexed: 01/23/2023]
|
74
|
Metabolic engineering of Escherichia coli for efficient free fatty acid production from glycerol. Metab Eng 2014; 25:82-91. [PMID: 25014174 DOI: 10.1016/j.ymben.2014.06.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 06/23/2014] [Accepted: 06/26/2014] [Indexed: 01/15/2023]
Abstract
Crude glycerol, generated as waste by-product in biodiesel production process, has been considered as an important carbon source for converting to value-added bioproducts recently. Free fatty acids (FFAs) can be used as precursors for the production of biofuels or biochemicals. Microbial biosynthesis of FFAs can be achieved by introducing an acyl-acyl carrier protein thioesterase into Escherichia coli. In this study, the effect of metabolic manipulation of FFAs synthesis cycle, host genetic background and cofactor engineering on FFAs production using glycerol as feed stocks was investigated. The highest concentration of FFAs produced by the engineered stain reached 4.82g/L with the yield of 29.55% (g FFAs/g glycerol), about 83% of the maximum theoretical pathway value by the type II fatty acid synthesis pathway. In addition, crude glycerol from biodiesel plant was also used as feedstock in this study. The FFA production was 3.53g/L with a yield of 24.13%. The yield dropped slightly when crude glycerol was used as a carbon source instead of pure glycerol, while it still can reach about 68% of the maximum theoretical pathway yield.
Collapse
|
75
|
Yu JL, Xia XX, Zhong JJ, Qian ZG. Direct biosynthesis of adipic acid from a synthetic pathway in recombinantEscherichia coli. Biotechnol Bioeng 2014; 111:2580-6. [DOI: 10.1002/bit.25293] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 05/06/2014] [Accepted: 05/14/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Jia-Le Yu
- State Key Laboratory of Bioreactor Engineering; School of Biotechnology, East China University of Science and Technology; 130 Meilong Road Shanghai 200237 China
| | - Xiao-Xia Xia
- State Key Laboratory of Microbial Metabolism; School of Life Sciences and Biotechnology, Shanghai Jiao Tong University; 800 Dong Chuan Road Shanghai 200240 China
| | - Jian-Jiang Zhong
- State Key Laboratory of Bioreactor Engineering; School of Biotechnology, East China University of Science and Technology; 130 Meilong Road Shanghai 200237 China
- State Key Laboratory of Microbial Metabolism; School of Life Sciences and Biotechnology, Shanghai Jiao Tong University; 800 Dong Chuan Road Shanghai 200240 China
| | - Zhi-Gang Qian
- State Key Laboratory of Microbial Metabolism; School of Life Sciences and Biotechnology, Shanghai Jiao Tong University; 800 Dong Chuan Road Shanghai 200240 China
| |
Collapse
|
76
|
Volker AR, Gogerty DS, Bartholomay C, Hennen-Bierwagen T, Zhu H, Bobik TA. Fermentative production of short-chain fatty acids in Escherichia coli. Microbiology (Reading) 2014; 160:1513-1522. [DOI: 10.1099/mic.0.078329-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Escherichia coli was engineered for the production of even- and odd-chain fatty acids (FAs) by fermentation. Co-production of thiolase, hydroxybutyryl-CoA dehydrogenase, crotonase and trans-enoyl-CoA reductase from a synthetic operon allowed the production of butyrate, hexanoate and octanoate. Elimination of native fermentation pathways by genetic deletion (ΔldhA, ΔadhE, ΔackA, Δpta, ΔfrdC) helped eliminate undesired by-products and increase product yields. Initial butyrate production rates were high (0.7 g l−1 h−1) but quickly levelled off and further study suggested this was due to product toxicity and/or acidification of the growth medium. Results also showed that endogenous thioesterases significantly influenced product formation. In particular, deletion of the yciA thioesterase gene substantially increased hexanoate production while decreasing the production of butyrate. E. coli was also engineered to co-produce enzymes for even-chain FA production (described above) together with a coenzyme B12-dependent pathway for the production of propionyl-CoA, which allowed the production of odd-chain FAs (pentanoate and heptanoate). The B12-dependent pathway used here has the potential to allow the production of odd-chain FAs from a single growth substrate (glucose) in a more energy-efficient manner than the prior methods.
Collapse
Affiliation(s)
- Alexandra R. Volker
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| | - David S. Gogerty
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| | - Christian Bartholomay
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| | - Tracie Hennen-Bierwagen
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| | - Huilin Zhu
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| | - Thomas A. Bobik
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| |
Collapse
|
77
|
Farasat I, Kushwaha M, Collens J, Easterbrook M, Guido M, Salis HM. Efficient search, mapping, and optimization of multi-protein genetic systems in diverse bacteria. Mol Syst Biol 2014; 10:731. [PMID: 24952589 PMCID: PMC4265053 DOI: 10.15252/msb.20134955] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Developing predictive models of multi-protein genetic systems to understand and optimize their behavior remains a combinatorial challenge, particularly when measurement throughput is limited. We developed a computational approach to build predictive models and identify optimal sequences and expression levels, while circumventing combinatorial explosion. Maximally informative genetic system variants were first designed by the RBS Library Calculator, an algorithm to design sequences for efficiently searching a multi-protein expression space across a > 10,000-fold range with tailored search parameters and well-predicted translation rates. We validated the algorithm's predictions by characterizing 646 genetic system variants, encoded in plasmids and genomes, expressed in six gram-positive and gram-negative bacterial hosts. We then combined the search algorithm with system-level kinetic modeling, requiring the construction and characterization of 73 variants to build a sequence-expression-activity map (SEAMAP) for a biosynthesis pathway. Using model predictions, we designed and characterized 47 additional pathway variants to navigate its activity space, find optimal expression regions with desired activity response curves, and relieve rate-limiting steps in metabolism. Creating sequence-expression-activity maps accelerates the optimization of many protein systems and allows previous measurements to quantitatively inform future designs.
Collapse
Affiliation(s)
- Iman Farasat
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, USA
| | - Manish Kushwaha
- Department of Biological Engineering, Pennsylvania State University, University Park, PA, USA
| | - Jason Collens
- Department of Biological Engineering, Pennsylvania State University, University Park, PA, USA
| | - Michael Easterbrook
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, USA
| | - Matthew Guido
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, USA
| | - Howard M Salis
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, USA Department of Biological Engineering, Pennsylvania State University, University Park, PA, USA
| |
Collapse
|
78
|
Xiong M, Schneiderman DK, Bates FS, Hillmyer MA, Zhang K. Scalable production of mechanically tunable block polymers from sugar. Proc Natl Acad Sci U S A 2014; 111:8357-62. [PMID: 24912182 PMCID: PMC4060720 DOI: 10.1073/pnas.1404596111] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Development of sustainable and biodegradable materials is essential for future growth of the chemical industry. For a renewable product to be commercially competitive, it must be economically viable on an industrial scale and possess properties akin or superior to existing petroleum-derived analogs. Few biobased polymers have met this formidable challenge. To address this challenge, we describe an efficient biobased route to the branched lactone, β-methyl-δ-valerolactone (βMδVL), which can be transformed into a rubbery (i.e., low glass transition temperature) polymer. We further demonstrate that block copolymerization of βMδVL and lactide leads to a new class of high-performance polyesters with tunable mechanical properties. Key features of this work include the creation of a total biosynthetic route to produce βMδVL, an efficient semisynthetic approach that employs high-yielding chemical reactions to transform mevalonate to βMδVL, and the use of controlled polymerization techniques to produce well-defined PLA-PβMδVL-PLA triblock polymers, where PLA stands for poly(lactide). This comprehensive strategy offers an economically viable approach to sustainable plastics and elastomers for a broad range of applications.
Collapse
Affiliation(s)
- Mingyong Xiong
- Departments of Chemical Engineering and Materials Science and
| | | | - Frank S Bates
- Departments of Chemical Engineering and Materials Science and
| | - Marc A Hillmyer
- Chemistry, University of Minnesota, Minneapolis, MN 55455-0431
| | - Kechun Zhang
- Departments of Chemical Engineering and Materials Science and
| |
Collapse
|
79
|
Engineering the productivity of recombinantEscherichia colifor limonene formation from glycerol in minimal media. Biotechnol J 2014; 9:1000-12. [DOI: 10.1002/biot.201400023] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 03/10/2014] [Accepted: 04/21/2014] [Indexed: 01/18/2023]
|
80
|
Quin MB, Schmidt-Dannert C. Designer microbes for biosynthesis. Curr Opin Biotechnol 2014; 29:55-61. [PMID: 24646570 DOI: 10.1016/j.copbio.2014.02.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/19/2014] [Accepted: 02/20/2014] [Indexed: 01/01/2023]
Abstract
Microbes have long been adapted for the biosynthetic production of useful compounds. There is increasing demand for the rapid and cheap microbial production of diverse molecules in an industrial setting. Microbes can now be designed and engineered for a particular biosynthetic purpose, thanks to recent developments in genome sequencing, metabolic engineering, and synthetic biology. Advanced tools exist for the genetic manipulation of microbes to create novel metabolic circuits, making new products accessible. Metabolic processes can be optimized to increase yield and balance pathway flux. Progress is being made towards the design and creation of fully synthetic microbes for biosynthetic purposes. Together, these emerging technologies will facilitate the production of designer microbes for biosynthesis.
Collapse
Affiliation(s)
- Maureen B Quin
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, 140 Gortner Laboratory, 1479 Gortner Avenue, Saint Paul, MN 55108, USA
| | - Claudia Schmidt-Dannert
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, 140 Gortner Laboratory, 1479 Gortner Avenue, Saint Paul, MN 55108, USA.
| |
Collapse
|
81
|
Jambunathan P, Zhang K. Novel pathways and products from 2-keto acids. Curr Opin Biotechnol 2014; 29:1-7. [PMID: 24492019 DOI: 10.1016/j.copbio.2014.01.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 01/13/2014] [Indexed: 01/23/2023]
Abstract
Since traditional chemical processes are non-renewable and environmentally unfriendly, biosynthesis is emerging as an attractive alternative for the production of advanced biofuels, chemicals, pharmaceuticals and polymers. Cost-competitive biomanufacturing requires the design of metabolic pathways that can achieve high production yields and rates. Recent advances in natural amino acid production have motivated the use of 2-ketoacid intermediates for the production of important chemicals. These 2-ketoacids undergo a wide range of efficient biochemical reactions leading to an array of industrially useful products. In this review, recently developed novel pathways based on 2-ketoacids will be described along with representative examples.
Collapse
Affiliation(s)
- Pooja Jambunathan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, MN 55455, USA
| | - Kechun Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, MN 55455, USA.
| |
Collapse
|
82
|
Thioesterases for ethylmalonyl-CoA pathway derived dicarboxylic acid production in Methylobacterium extorquens AM1. Appl Microbiol Biotechnol 2014; 98:4533-44. [PMID: 24419796 DOI: 10.1007/s00253-013-5456-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/03/2013] [Accepted: 12/05/2013] [Indexed: 11/27/2022]
Abstract
The ethylmalonyl-coenzyme A pathway (EMCP) is a recently discovered pathway present in diverse α-proteobacteria such as the well studied methylotroph Methylobacterium extorquens AM1. Its glyoxylate regeneration function is obligatory during growth on C1 carbon sources like methanol. The EMCP contains special CoA esters, of which dicarboxylic acid derivatives are of high interest as building blocks for chemical industry. The possible production of dicarboxylic acids out of the alternative, non-food competing C-source methanol could lead to sustainable and economic processes. In this work we present a testing of functional thioesterases being active towards the EMCP CoA esters including in vitro enzymatic assays and in vivo acid production. Five thioesterases including TesB from Escherichia coli and M. extorquens, YciA from E. coli, Bch from Bacillus subtilis and Acot4 from Mus musculus showed activity towards EMCP CoA esters in vitro at which YciA was most active. Expressing yciA in M. extorquens AM1 led to release of 70 mg/l mesaconic and 60 mg/l methylsuccinic acid into culture supernatant during exponential growth phase. Our data demonstrates the biotechnological applicability of the thioesterase YciA and the possibility of EMCP dicarboxylic acid production from methanol using M. extorquens AM1.
Collapse
|
83
|
Pathway and protein engineering approaches to produce novel and commodity small molecules. Curr Opin Biotechnol 2013; 24:1137-43. [DOI: 10.1016/j.copbio.2013.02.019] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/07/2013] [Accepted: 02/20/2013] [Indexed: 11/19/2022]
|
84
|
Functional screening and in vitro analysis reveal thioesterases with enhanced substrate specificity profiles that improve short-chain fatty acid production in Escherichia coli. Appl Environ Microbiol 2013; 80:1042-50. [PMID: 24271180 DOI: 10.1128/aem.03303-13] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Short-chain fatty acid (SCFA) biosynthesis is pertinent to production of biofuels, industrial compounds, and pharmaceuticals from renewable resources. To expand on Escherichia coli SCFA products, we previously implemented a coenzyme A (CoA)-dependent pathway that condenses acetyl-CoA to a diverse group of short-chain fatty acyl-CoAs. To increase product titers and reduce premature pathway termination products, we conducted in vivo and in vitro analyses to understand and improve the specificity of the acyl-CoA thioesterase enzyme, which releases fatty acids from CoA. A total of 62 putative bacterial thioesterases, including 23 from the cow rumen microbiome, were inserted into a pathway that condenses acetyl-CoA to an acyl-CoA molecule derived from exogenously provided propionic or isobutyric acid. Functional screening revealed thioesterases that increase production of saturated (valerate), unsaturated (trans-2-pentenoate), and branched (4-methylvalerate) SCFAs compared to overexpression of E. coli thioesterase tesB or native expression of endogenous thioesterases. To determine if altered thioesterase acyl-CoA substrate specificity caused the increase in product titers, six of the most promising enzymes were analyzed in vitro. Biochemical assays revealed that the most productive thioesterases rely on promiscuous activity but have greater specificity for product-associated acyl-CoAs than for precursor acyl-CoAs. In this study, we introduce novel thioesterases with improved specificity for saturated, branched, and unsaturated short-chain acyl-CoAs, thereby expanding the diversity of potential fatty acid products while increasing titers of current products. The growing uncertainty associated with protein database annotations denotes this study as a model for isolating functional biochemical pathway enzymes in situations where experimental evidence of enzyme function is absent.
Collapse
|
85
|
Zingaro KA, Nicolaou SA, Papoutsakis ET. Dissecting the assays to assess microbial tolerance to toxic chemicals in bioprocessing. Trends Biotechnol 2013; 31:643-53. [DOI: 10.1016/j.tibtech.2013.08.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/14/2013] [Accepted: 08/19/2013] [Indexed: 11/15/2022]
|
86
|
Tailored fatty acid synthesis via dynamic control of fatty acid elongation. Proc Natl Acad Sci U S A 2013; 110:11290-5. [PMID: 23798438 DOI: 10.1073/pnas.1307129110] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Medium-chain fatty acids (MCFAs, 4-12 carbons) are valuable as precursors to industrial chemicals and biofuels, but are not canonical products of microbial fatty acid synthesis. We engineered microbial production of the full range of even- and odd-chain-length MCFAs and found that MCFA production is limited by rapid, irreversible elongation of their acyl-ACP precursors. To address this limitation, we programmed an essential ketoacyl synthase to degrade in response to a chemical inducer, thereby slowing acyl-ACP elongation and redirecting flux from phospholipid synthesis to MCFA production. Our results show that induced protein degradation can be used to dynamically alter metabolic flux, and thereby increase the yield of a desired compound. The strategy reported herein should be widely useful in a range of metabolic engineering applications in which essential enzymes divert flux away from a desired product, as well as in the production of polyketides, bioplastics, and other recursively synthesized hydrocarbons for which chain-length control is desired.
Collapse
|
87
|
Glasgow JE, Tullman-Ercek D. Synthetic biologists spring into action at the 245th American Chemical Society National Meeting. ACS Synth Biol 2013; 2:293-5. [PMID: 24884108 DOI: 10.1021/sb400046t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As the field of synthetic biology continues to define itself, it has merged concepts from many related areas of research: molecular biology, genetics, bioengineering, and chemistry. At the 2013 Spring American Chemical Society National Meeting in New Orleans, LA, this mixture was manifested in a wealth of sessions emphasizing the use of modern synthetic biological approaches to solve many of today's biggest chemical problems. As a result of the field's diverse yet pervasive nature, synthetic biology concepts were present in several of the conferences many divisions, including Biological Chemistry, Biochemical Technology, Cellulose and Renewable Materials, and several others. Here we offer a snapshot of some of the exciting research discussed in the dedicated synthetic biology sessions throughout the week.
Collapse
Affiliation(s)
- Jeff E. Glasgow
- Department
of Chemistry and ‡Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720,
United States
| | - Danielle Tullman-Ercek
- Department
of Chemistry and ‡Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720,
United States
| |
Collapse
|
88
|
Frasch HJ, Medema MH, Takano E, Breitling R. Design-based re-engineering of biosynthetic gene clusters: plug-and-play in practice. Curr Opin Biotechnol 2013; 24:1144-50. [PMID: 23540422 DOI: 10.1016/j.copbio.2013.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/05/2013] [Indexed: 11/18/2022]
Abstract
Synthetic biology is revolutionizing the way in which the biosphere is explored for natural products. Through computational genome mining, thousands of biosynthetic gene clusters are being identified in microbial genomes, which constitute a rich source of potential novel pharmaceuticals. New methods are currently being devised to prioritize these gene clusters in terms of their potential for yielding biochemical novelty. High-potential gene clusters from any biological source can then be activated by 'refactoring' their native regulatory machinery, replacing it by synthetic, orthogonal regulation and optimizing enzyme expression to function effectively in an industry-compatible target host. Various part libraries and assembly technologies have recently been developed which facilitate this process.
Collapse
Affiliation(s)
- Hans-Jörg Frasch
- Department of Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | | | | | | |
Collapse
|