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Su H, Lin J. Biosynthesis pathways of expanding carbon chains for producing advanced biofuels. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:109. [PMID: 37400889 DOI: 10.1186/s13068-023-02340-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 05/11/2023] [Indexed: 07/05/2023]
Abstract
Because the thermodynamic property is closer to gasoline, advanced biofuels (C ≥ 6) are appealing for replacing non-renewable fossil fuels using biosynthesis method that has presented a promising approach. Synthesizing advanced biofuels (C ≥ 6), in general, requires the expansion of carbon chains from three carbon atoms to more than six carbon atoms. Despite some specific biosynthesis pathways that have been developed in recent years, adequate summary is still lacking on how to obtain an effective metabolic pathway. Review of biosynthesis pathways for expanding carbon chains will be conducive to selecting, optimizing and discovering novel synthetic route to obtain new advanced biofuels. Herein, we first highlighted challenges on expanding carbon chains, followed by presentation of two biosynthesis strategies and review of three different types of biosynthesis pathways of carbon chain expansion for synthesizing advanced biofuels. Finally, we provided an outlook for the introduction of gene-editing technology in the development of new biosynthesis pathways of carbon chain expansion.
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Affiliation(s)
- Haifeng Su
- Key Laboratory of Degraded and Unused Land Consolidation Engineering, The Ministry of Natural and Resources, Xian, 710075, Shanxi, China
| | - JiaFu Lin
- Antibiotics Research and Re-Evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu, 610106, China.
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2
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Sheng Q, Wu XY, Xu X, Tan X, Li Z, Zhang B. Production of l-glutamate family amino acids in Corynebacterium glutamicum: Physiological mechanism, genetic modulation, and prospects. Synth Syst Biotechnol 2021; 6:302-325. [PMID: 34632124 PMCID: PMC8484045 DOI: 10.1016/j.synbio.2021.09.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/30/2021] [Accepted: 09/08/2021] [Indexed: 11/19/2022] Open
Abstract
l-glutamate family amino acids (GFAAs), consisting of l-glutamate, l-arginine, l-citrulline, l-ornithine, l-proline, l-hydroxyproline, γ-aminobutyric acid, and 5-aminolevulinic acid, are widely applied in the food, pharmaceutical, cosmetic, and animal feed industries, accounting for billions of dollars of market activity. These GFAAs have many functions, including being protein constituents, maintaining the urea cycle, and providing precursors for the biosynthesis of pharmaceuticals. Currently, the production of GFAAs mainly depends on microbial fermentation using Corynebacterium glutamicum (including its related subspecies Corynebacterium crenatum), which is substantially engineered through multistep metabolic engineering strategies. This review systematically summarizes recent advances in the metabolic pathways, regulatory mechanisms, and metabolic engineering strategies for GFAA accumulation in C. glutamicum and C. crenatum, which provides insights into the recent progress in l-glutamate-derived chemical production.
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Affiliation(s)
- Qi Sheng
- Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Xiao-Yu Wu
- Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Xinyi Xu
- Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
| | - Xiaoming Tan
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, China
| | - Zhimin Li
- Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, China
- Corresponding author. Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China.
| | - Bin Zhang
- Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China
- Corresponding author. Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, China.
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Biorefinery: The Production of Isobutanol from Biomass Feedstocks. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10228222] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Environmental issues have prompted the vigorous development of biorefineries that use agricultural waste and other biomass feedstock as raw materials. However, most current biorefinery products are cellulosic ethanol. There is an urgent need for biorefineries to expand into new bioproducts. Isobutanol is an important bulk chemical with properties that are close to gasoline, making it a very promising biofuel. The use of microorganisms to produce isobutanol has been extensively studied, but there is still a considerable gap to achieving the industrial production of isobutanol from biomass. This review summarizes current metabolic engineering strategies that have been applied to biomass isobutanol production and recent advances in the production of isobutanol from different biomass feedstocks.
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Enriching the Production of 2-Methyl-1-Butanol in Fermentation Process Using Corynebacterium crenatum. Curr Microbiol 2020; 77:1699-1706. [PMID: 32300924 DOI: 10.1007/s00284-020-01961-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/21/2020] [Indexed: 10/24/2022]
Abstract
Non-natural 2-methyl-1-butanol (2 MB) has been biosynthesized through the modification of metabolic pathways using Corynebacterium crenatum, a non-model host. However, its production capacity is not effectively improved. In this study, the fermentation process was strengthened through factor combination design (FCD) for enhancing the production of 2 MB. Our results showed that the highest production of 2 MB, 3-methyl-1-butanol (3 MB), ethanol, and total solvent was 4.87 ± 0.39 g/L, 3.57 ± 0.21 g/L, 5.74 ± 0.43 g/L, and 14.18 g/L, respectively, under the optimal fermentation conditions. The optimal fermentation conditions were determined through the FCD to be as follows: pH of 6.5, IPTG concentration of 1.2 mM, fermentation temperature of 32 °C, and fermentation time of 96 h. This study provides a significant guidance for the optimal control technology of the genetically engineered C. crenatum, and also a useful reference for the industrial production of 2 MB via the microbial fermentation approach.
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Acedos MG, Ramon A, de la Morena S, Santos VE, Garcia-Ochoa F. Isobutanol production by a recombinant biocatalyst Shimwellia blattae (p424IbPSO): Study of the operational conditions. Biochem Eng J 2018. [DOI: 10.1016/j.bej.2018.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Oliveira A, Oliveira LC, Aburjaile F, Benevides L, Tiwari S, Jamal SB, Silva A, Figueiredo HCP, Ghosh P, Portela RW, De Carvalho Azevedo VA, Wattam AR. Insight of Genus Corynebacterium: Ascertaining the Role of Pathogenic and Non-pathogenic Species. Front Microbiol 2017; 8:1937. [PMID: 29075239 PMCID: PMC5643470 DOI: 10.3389/fmicb.2017.01937] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/21/2017] [Indexed: 11/22/2022] Open
Abstract
This review gathers recent information about genomic and transcriptomic studies in the Corynebacterium genus, exploring, for example, prediction of pathogenicity islands and stress response in different pathogenic and non-pathogenic species. In addition, is described several phylogeny studies to Corynebacterium, exploring since the identification of species until biological speciation in one species belonging to the genus Corynebacterium. Important concepts associated with virulence highlighting the role of Pld protein and Tox gene. The adhesion, characteristic of virulence factor, was described using the sortase mechanism that is associated to anchorage to the cell wall. In addition, survival inside the host cell and some diseases, were too addressed for pathogenic corynebacteria, while important biochemical pathways and biotechnological applications retain the focus of this review for non-pathogenic corynebacteria. Concluding, this review broadly explores characteristics in genus Corynebacterium showing to have strong relevance inside the medical, veterinary, and biotechnology field.
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Affiliation(s)
- Alberto Oliveira
- Molecular and Cellular Laboratory, General Biology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Leticia C Oliveira
- Molecular and Cellular Laboratory, General Biology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Flavia Aburjaile
- Center of Genomics and System Biology, Federal University of Pará, Belém, Brazil
| | - Leandro Benevides
- Molecular and Cellular Laboratory, General Biology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Sandeep Tiwari
- Molecular and Cellular Laboratory, General Biology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Syed B Jamal
- Molecular and Cellular Laboratory, General Biology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Arthur Silva
- Center of Genomics and System Biology, Federal University of Pará, Belém, Brazil
| | - Henrique C P Figueiredo
- Aquacen, National Reference Laboratory for Aquatic Animal Diseases, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Preetam Ghosh
- Department of Computational Science, Virginia Commonwealth University, Richmond, VA, United States
| | - Ricardo W Portela
- Laboratory of Immunology and Molecular Bióloga, Health Sciences Institute, Federal University of Bahiaa, Salvador, Brazil
| | - Vasco A De Carvalho Azevedo
- Molecular and Cellular Laboratory, General Biology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Alice R Wattam
- Biocomplexity Institute of Virginia Tech, Virginia Tech, Blacksburg, VA, United States
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Ye W, Li J, Han R, Xu G, Dong J, Ni Y. Engineering coenzyme A-dependent pathway from Clostridium saccharobutylicum in Escherichia coli for butanol production. BIORESOURCE TECHNOLOGY 2017; 235:140-148. [PMID: 28365341 DOI: 10.1016/j.biortech.2017.03.085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 06/07/2023]
Abstract
Clostridium saccharobutylicum has been proved to be efficient in butanol fermentation from various feedstocks. Whereas, lack of genetic manipulation system has severely hindered the engineering of C. saccharobutylicum for more extensive applications. In this study, recombinant Escherichia coli harboring heterologous coenzyme A-dependent pathway from C. saccharobutylicum DSM 13864 was constructed, which consisted of solventogenic pathway genes: acetoacetyl-CoA thiolase (thlA), aldehyde/alcohol dehydrogenase (adhE2) and bcs-operon (crt-bcd1-etfB2-fixB2-hbd). Then, a butanol titer of 67mg/L was attained. After replacing thlA with acetyl-CoA acetyltransferase (atoB) from E. coli and deleting the competitive branch genes lactate dehydrogenase (ldhA), aldehyde/alcohol dehydrogenase (adhE1) and fumarate reductase (frdBC), the butanol titer was successfully improved for 3.8-fold (254mg/L). Under the optimum fermentation conditions, the final butanol titer reached 584mg/L after 120h. This result demonstrates the feasibility of adapting CoA-dependent solventogenic pathway from C. saccharobutylicum in E. coli for butanol synthesis.
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Affiliation(s)
- Weihua Ye
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jin Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Ruizhi Han
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Guochao Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jinjun Dong
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Ye Ni
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
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Su H, Lin J, Wang Y, Chen Q, Wang G, Tan F. Engineering Brevibacterium flavum
for the production of renewable bioenergy: C4-C5 advanced alcohols. Biotechnol Bioeng 2017; 114:1946-1958. [DOI: 10.1002/bit.26324] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 04/18/2017] [Accepted: 04/26/2017] [Indexed: 12/30/2022]
Affiliation(s)
- HaiFeng Su
- Chongqing Institute of Green and Interligent Technology; Chinese Academy of Science; 266, Fangzheng Avenue, Shuitu High-Tech Park, Beibei Chongqing 400714 P. R. China
| | - JiaFu Lin
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province; Sichuan Industrial Institute of Antibiotics, Chengdu University; Chengdu P. R. China
| | - YuanHong Wang
- Center of Analysis and Testing; School of Public Health; Institute of Analytical Chemistry for Life Science; Nantong University; Nantong P. R. China
| | - Qiao Chen
- Chongqing Institute of Green and Interligent Technology; Chinese Academy of Science; 266, Fangzheng Avenue, Shuitu High-Tech Park, Beibei Chongqing 400714 P. R. China
| | - GuangWei Wang
- Chongqing Institute of Green and Interligent Technology; Chinese Academy of Science; 266, Fangzheng Avenue, Shuitu High-Tech Park, Beibei Chongqing 400714 P. R. China
| | - FuRong Tan
- Biogas Institute of Ministry of Agriculture; Chengdu 610041 Sichuan P. R. China
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Metabolic engineering of Corynebacterium crenatium for enhancing production of higher alcohols. Sci Rep 2016; 6:39543. [PMID: 27996038 PMCID: PMC5172369 DOI: 10.1038/srep39543] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/24/2016] [Indexed: 12/19/2022] Open
Abstract
Biosynthesis approaches for the production of higher alcohols as a source of alternative fossil fuels have garnered increasing interest recently. However, there is little information available in the literature about using undirected whole-cell mutagenesis (UWCM) in vivo to improve higher alcohols production. In this study, for the first time, we approached this question from two aspects: first preferentially improving the capacity of expression host, and subsequently optimizing metabolic pathways using multiple genetic mutations to shift metabolic flux toward the biosynthetic pathway of target products to convert intermediate 2-keto acid compounds into diversified C4~C5 higher alcohols using UWCM in vivo, with the aim of improving the production. The results demonstrated the production of higher alcohols including isobutanol, 2-methyl-1-butanol, 3-methyl-1-butanol from glucose and duckweed under simultaneous saccharification and fermentation (SSF) scheme were higher based on the two aspects compared with only the use of wild-type stain as expression host. These findings showed that the improvement via UWCM in vivo in the two aspects for expression host and metabolic flux can facilitate the increase of higher alcohols production before using gene editing technology. Our work demonstrates that a multi-faceted approach for the engineering of novel synthetic pathways in microorganisms for improving biofuel production is feasible.
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Chen L, Yu C, Ma Y, Xu H, Wang S, Wang Y, Liu X, Zhou G. Insights into the structural and physicochemical properties of small granular starches from two hydrophyte duckweeds, Spirodela oligorrhiza and Lemna minor. Carbohydr Res 2016; 435:208-214. [PMID: 27816839 DOI: 10.1016/j.carres.2016.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 10/22/2016] [Accepted: 10/24/2016] [Indexed: 11/17/2022]
Abstract
The structure and physicochemical properties of starches from two hydrophyte duckweeds, Spirodela oligorrhiza and Lemna minor, were investigated and compared in this study. The amylose content and average size of starches were determined to be 20.85%, 4.70 μm and 27.77%, 6.17 μm for Spirodela oligorrhiza and Lemna minor, respectively. The average chain length of two duckweed starches was measured to be around DP 28. The chain length distribution was observed to be greatly different from other reported starches for the high proportion of long chains (DP ≥ 37) over 50%. Wide-angle X-ray diffraction profiles of the two starch samples displayed typical B-type diffraction pattern. The gelatinization enthalpy-changes (ΔHgel) of two starch samples was about 10.40 J/g for two duckweed starches. The present results suggested the potential utilization of small granular starches from duckweed in functional foods and dietary supplement products.
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Affiliation(s)
- Lei Chen
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Changjiang Yu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yubin Ma
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Hua Xu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Shumin Wang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Yu Wang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Xingxun Liu
- Institute of Food Science and Technology (IFST), Chinese Academy of Agricultural Science (CAAS), Beijing 100193, China
| | - Gongke Zhou
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
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12
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Yamamoto K, Tsuchisaka A, Yukawa H. Branched-Chain Amino Acids. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 159:103-128. [PMID: 27872960 DOI: 10.1007/10_2016_28] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Branched-chain amino acids (BCAAs), viz., L-isoleucine, L-leucine, and L-valine, are essential amino acids that cannot be synthesized in higher organisms and are important nutrition for humans as well as livestock. They are also valued as synthetic intermediates for pharmaceuticals. Therefore, the demand for BCAAs in the feed and pharmaceutical industries is increasing continuously. Traditional industrial fermentative production of BCAAs was performed using microorganisms isolated by random mutagenesis. A collection of these classical strains was also scientifically useful to clarify the details of the BCAA biosynthetic pathways, which are tightly regulated by feedback inhibition and transcriptional attenuation. Based on this understanding of the metabolism of BCAAs, it is now possible for us to pursue strains with higher BCAA productivity using rational design and advanced molecular biology techniques. Additionally, systems biology approaches using augmented omics information help us to optimize carbon flux toward BCAA production. Here, we describe the biosynthetic pathways of BCAAs and their regulation and then overview the microorganisms developed for BCAA production. Other chemicals, including isobutanol, i.e., a second-generation biofuel, can be synthesized by branching the BCAA biosynthetic pathways, which are also outlined.
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Affiliation(s)
- Keisuke Yamamoto
- Green Earth Institute Co., Ltd, Hongo, Tokyo, Japan
- Green Earth Research Center, Kisarazu, Chiba, Japan
| | - Atsunari Tsuchisaka
- Green Earth Institute Co., Ltd, Hongo, Tokyo, Japan
- Green Earth Research Center, Kisarazu, Chiba, Japan
| | - Hideaki Yukawa
- Green Earth Institute Co., Ltd, Hongo, Tokyo, Japan.
- Green Earth Research Center, Kisarazu, Chiba, Japan.
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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.
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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.
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