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Zhang J, Li F, Liu D, Liu Q, Song H. Engineering extracellular electron transfer pathways of electroactive microorganisms by synthetic biology for energy and chemicals production. Chem Soc Rev 2024; 53:1375-1446. [PMID: 38117181 DOI: 10.1039/d3cs00537b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
The excessive consumption of fossil fuels causes massive emission of CO2, leading to climate deterioration and environmental pollution. The development of substitutes and sustainable energy sources to replace fossil fuels has become a worldwide priority. Bio-electrochemical systems (BESs), employing redox reactions of electroactive microorganisms (EAMs) on electrodes to achieve a meritorious combination of biocatalysis and electrocatalysis, provide a green and sustainable alternative approach for bioremediation, CO2 fixation, and energy and chemicals production. EAMs, including exoelectrogens and electrotrophs, perform extracellular electron transfer (EET) (i.e., outward and inward EET), respectively, to exchange energy with the environment, whose rate determines the efficiency and performance of BESs. Therefore, we review the synthetic biology strategies developed in the last decade for engineering EAMs to enhance the EET rate in cell-electrode interfaces for facilitating the production of electricity energy and value-added chemicals, which include (1) progress in genetic manipulation and editing tools to achieve the efficient regulation of gene expression, knockout, and knockdown of EAMs; (2) synthetic biological engineering strategies to enhance the outward EET of exoelectrogens to anodes for electricity power production and anodic electro-fermentation (AEF) for chemicals production, including (i) broadening and strengthening substrate utilization, (ii) increasing the intracellular releasable reducing equivalents, (iii) optimizing c-type cytochrome (c-Cyts) expression and maturation, (iv) enhancing conductive nanowire biosynthesis and modification, (v) promoting electron shuttle biosynthesis, secretion, and immobilization, (vi) engineering global regulators to promote EET rate, (vii) facilitating biofilm formation, and (viii) constructing cell-material hybrids; (3) the mechanisms of inward EET, CO2 fixation pathway, and engineering strategies for improving the inward EET of electrotrophic cells for CO2 reduction and chemical production, including (i) programming metabolic pathways of electrotrophs, (ii) rewiring bioelectrical circuits for enhancing inward EET, and (iii) constructing microbial (photo)electrosynthesis by cell-material hybridization; (4) perspectives on future challenges and opportunities for engineering EET to develop highly efficient BESs for sustainable energy and chemical production. We expect that this review will provide a theoretical basis for the future development of BESs in energy harvesting, CO2 fixation, and chemical synthesis.
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Affiliation(s)
- Junqi Zhang
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Feng Li
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Dingyuan Liu
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Qijing Liu
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Hao Song
- Frontier Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
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2
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Tang R, Yuan X, Yang J. Problems and corresponding strategies for converting CO 2 into value-added products in Cupriavidus necator H16 cell factories. Biotechnol Adv 2023; 67:108183. [PMID: 37286176 DOI: 10.1016/j.biotechadv.2023.108183] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/17/2023] [Accepted: 05/31/2023] [Indexed: 06/09/2023]
Abstract
Elevated CO2 emissions have substantially altered the worldwide climate, while the excessive reliance on fossil fuels has exacerbated the energy crisis. Therefore, the conversion of CO2 into fuel, petroleum-based derivatives, drug precursors, and other value-added products is expected. Cupriavidus necator H16 is the model organism of the "Knallgas" bacterium and is considered to be a microbial cell factory as it can convert CO2 into various value-added products. However, the development and application of C. necator H16 cell factories has several limitations, including low efficiency, high cost, and safety concerns arising from the autotrophic metabolic characteristics of the strains. In this review, we first considered the autotrophic metabolic characteristics of C. necator H16, and then categorized and summarized the resulting problems. We also provided a detailed discussion of some corresponding strategies concerning metabolic engineering, trophic models, and cultivation mode. Finally, we provided several suggestions for improving and combining them. This review might help in the research and application of the conversion of CO2 into value-added products in C. necator H16 cell factories.
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Affiliation(s)
- Ruohao Tang
- Energy-rich Compounds Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, Shandong Province, People's Republic of China; Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong Province, People's Republic of China
| | - Xianzheng Yuan
- Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong Province, People's Republic of China
| | - Jianming Yang
- Energy-rich Compounds Production by Photosynthetic Carbon Fixation Research Center, Shandong Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, Shandong Province, People's Republic of China.
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3
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Wang X, Han Q, Yu Q, Wang S, Yang J, Su W, Wan-Yan R, Sun X, Li H. Mammalian carcass decay increases carbon storage and temporal turnover of carbon-fixing microbes in alpine meadow soil. ENVIRONMENTAL RESEARCH 2023; 225:115653. [PMID: 36898422 DOI: 10.1016/j.envres.2023.115653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/20/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Corpse decomposition is of great significance to the carbon cycle of natural ecosystem. Carbon fixation is a carbon conversion process that converts carbon dioxide into organic carbon, which greatly contributes to carbon emission reduction. However, the effects of wild animal carcass decay on carbon-fixing microbes in grassland soil environment are still unknown. In this research, thirty wild mammal (Ochotona curzoniae) corpses were placed on alpine meadow soil to study the carbon storage and carbon-fixing microbiota succession for a 94-day decomposition using next-generation sequencing. Our results revealed that 1) the concentration of total carbon increased approximately 2.24-11.22% in the corpse group. 2) Several carbon-fixing bacterial species (Calothrix parietina, Ancylobacter rudongensis, Rhodopseudomonas palustris) may predict the concentration of total carbon. 3) Animal cadaver degradation caused the differentiation of carbon-fixing microbiota structures during succession and made the medium-stage networks of carbon-fixing microbes more complicated. 4) The temporal turnover rate in the experimental groups was higher than that in the control groups, indicating a quick change of gravesoil carbon-fixing microbiota. 5) The deterministic process dominates the assembly mechanism of experimental groups (ranging from 53.42% to 94.94%), which reflects that the carbon-fixing microbial community in gravesoil can be regulated. Under global climate change, this study provides a new perspective for understanding the effects of wild animal carcass decay on soil carbon storage and carbon-fixing microbes.
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Affiliation(s)
- Xiaochen Wang
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Qian Han
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Qiaoling Yu
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Sijie Wang
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Jiawei Yang
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Wanghong Su
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Ruijun Wan-Yan
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Xiaofang Sun
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China
| | - Huan Li
- Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, 730000, China; State Key Laboratory of Grassland Agro-ecosystems, Center for Grassland Microbiome, Lanzhou University, Lanzhou, 730000, China.
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4
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Xu J, Wang J, Ma C, Wei Z, Zhai Y, Tian N, Zhu Z, Xue M, Li D. Embracing a low-carbon future by the production and marketing of C1 gas protein. Biotechnol Adv 2023; 63:108096. [PMID: 36621726 DOI: 10.1016/j.biotechadv.2023.108096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 12/14/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023]
Abstract
Food scarcity and environmental deterioration are two major problems that human populations currently face. Fortunately, the disruptive innovation of raw food materials has been stimulated by the rapid evolution of biomanufacturing. Therefore, it is expected that the new trends in technology will not only alter the natural resource-dependent food production systems and the traditional way of life but also reduce and assimilate the greenhouse gases released into the atmosphere. This review article summarizes the metabolic pathways associated with C1 gas conversion and the production of single-cell protein for animal feed. Moreover, the protein function, worldwide authorization, market access, and methods to overcome challenges in C1 gas assimilation microbial cell factory construction are also provided. With widespread attention and increasing policy support, the production of C1 gas protein will bring more opportunities and make tremendous contributions to our sustainable future.
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Affiliation(s)
- Jian Xu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China; Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin, China
| | - Jie Wang
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Chunling Ma
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; Haihe Laboratory of Synthetic Biology, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China
| | - Zuoxi Wei
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China; Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin, China
| | - Yida Zhai
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China; Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin, China
| | - Na Tian
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China; Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin, China
| | - Zhiguang Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China.
| | - Min Xue
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Demao Li
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China; National Centre of Technology Innovation for Synthetic Biology, Tianjin, China; Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin, China.
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5
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Han Y, Wang Q, Li Q, Hu C. Active metabolism and biomass dynamics of biocrusts are shaped by variation in their successional state and seasonal energy sources. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 831:154756. [PMID: 35339556 DOI: 10.1016/j.scitotenv.2022.154756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
Seasonal growth and changes in biomass within communities are the core of ecosystem dynamics. Biocrusts play a prominent role as pioneers in dryland soils. However, the seasonal dynamics of biocrusts remain poorly resolved. In this study, we collected biocrusts across a successional gradient (cyanobacteria, cyanolichen, chlorolichen, and moss-dominated) from southeastern Tengger Desert (China) during the summer and autumn seasons, and explored seasonal changes in metabolism and biomass using multi-omics approaches. We found that Cyanobacteria and Ascomycota were the dominant active taxa and both exhibited higher abundances in autumn. We also found that the dominant primary producers in biocrusts strongly affected community-wide characteristics of metabolism. Along with seasonal differences in light energy utilization, utilization of inorganic energy sources exhibited higher expression in the summer while for organic sources, in the autumn. We found that overall metabolism was significantly regulated by the ratio of intracellular to extracellular polymer degradation, and affected by NO3-, PO43- and EC (in the summer)/NO2- (in the autumn). In summary, biocrust growth varied with seasonal variation in light energy utilization and complementary chemical energy sources, with the most suitable season varying with biocrust successional type.
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Affiliation(s)
- Yingchun Han
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiong Wang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunxiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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6
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Yau MCM, Hayes M, Kalathil S. Biocatalytic conversion of sunlight and carbon dioxide to solar fuels and chemicals. RSC Adv 2022; 12:16396-16411. [PMID: 35754911 PMCID: PMC9169074 DOI: 10.1039/d2ra00673a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/25/2022] [Indexed: 11/21/2022] Open
Abstract
This review discusses the progress in the assembly of photosynthetic biohybrid systems using enzymes and microbes as the biocatalysts which are capable of utilising light to reduce carbon dioxide to solar fuels. We begin by outlining natural photosynthesis, an inspired biomachinery to develop artificial photosystems, and the rationale and motivation to advance and introduce biological substrates to create more novel, and efficient, photosystems. The case studies of various approaches to the development of CO2-reducing microbial semi-artificial photosystems are also summarised, showcasing a variety of methods for hybrid microbial photosystems and their potential. Finally, approaches to investigate the relatively ambiguous electron transfer mechanisms in such photosystems are discussed through the presentation of spectroscopic techniques, eventually leading to what this will mean for the future of microbial hybrid photosystems.
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Affiliation(s)
- Mandy Ching Man Yau
- Hub for Biotechnology in the Built Environment, Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University Newcastle NE1 8ST UK
| | - Martin Hayes
- Johnson Matthey Technology Centre Cambridge Science Park, Milton Road Cambridge CB4 0FP UK
| | - Shafeer Kalathil
- Hub for Biotechnology in the Built Environment, Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University Newcastle NE1 8ST UK
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7
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Light-driven carbon dioxide reduction to methane by Methanosarcina barkeri in an electric syntrophic coculture. THE ISME JOURNAL 2022; 16:370-377. [PMID: 34341507 PMCID: PMC8776907 DOI: 10.1038/s41396-021-01078-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 02/07/2023]
Abstract
The direct conversion of CO2 to value-added chemical commodities, thereby storing solar energy, offers a promising option for alleviating both the current energy crisis and global warming. Semiconductor-biological hybrid systems are novel approaches. However, the inherent defects of photocorrosion, photodegradation, and the toxicity of the semiconductor limit the application of these biohybrid systems. We report here that Rhodopseudomonas palustris was able to directly act as a living photosensitizer to drive CO2 to CH4 conversion by Methanosarcina barkeri under illumination after coculturing. Specifically, R. palustris formed a direct electric syntrophic coculture with M. barkeri. Here, R. palustris harvested solar energy, performed anoxygenic photosynthesis using sodium thiosulfate as an electron donor, and transferred electrons extracellularly to M. barkeri to drive methane generation. The methanogenesis of M. barkeri in coculture was a light-dependent process with a production rate of 4.73 ± 0.23 μM/h under light, which is slightly higher than that of typical semiconductor-biohybrid systems (approximately 4.36 μM/h). Mechanistic and transcriptomic analyses showed that electrons were transferred either directly or indirectly (via electron shuttles), subsequently driving CH4 production. Our study suggests that R. palustris acts as a natural photosensitizer that, in coculture with M. barkeri, results in a new way to harvest solar energy that could potentially replace semiconductors in biohybrid systems.
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8
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Coordinating Carbon Metabolism and Cell Cycle of Chlamydomonasreinhardtii with Light Strategies under Nitrogen Recovery. Microorganisms 2021; 9:microorganisms9122480. [PMID: 34946081 PMCID: PMC8707240 DOI: 10.3390/microorganisms9122480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 11/17/2022] Open
Abstract
Nutrient supplementation is common in microalgae cultivation to enhance the accumulation of biomass and biofunctional products, while the recovery mechanism from nutrient starvation is less investigated. In this study, the influence of remodeled carbon metabolism on cell cycle progression was explored by using different light wavelengths under N-repletion and N-recovery. The results suggested that blue light enhanced cell enlargement and red light promoted cell division under N-repletion. On the contrary, blue light promoted cell division by stimulating cell cycle progression under N-recovery. This interesting phenomenon was ascribed to different carbon metabolisms under N-repletion and N-recovery. Blue light promoted the recovery of photosystem II and redirected carbon skeletons into proteins under N-recovery, which potentially accelerated cell recovery and cell cycle progression. Although red light also facilitated the recovery of photosystem II, it mitigated the degradation of polysaccharide and then arrested almost all the cells in the G1 phase. By converting light wavelengths at the 12 h of N-recovery with blue light, red and white lights were proved to increase biomass concentration better than continuous blue light. These results revealed different mechanisms of cell metabolism of Chlamydomonas reinhardtii during N-recovery and could be applied to enhance cell vitality of microalgae from nutrient starvation and boost biomass production.
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9
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Ma Z, Liu D, Liu M, Cao Y, Song H. From CO<sub>2</sub> to high value-added products: Advances on carbon sequestration by <italic>Ralstonia eutropha</italic> H16. CHINESE SCIENCE BULLETIN-CHINESE 2021. [DOI: 10.1360/tb-2021-0584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Bio-conversion of CO 2 into biofuels and other value-added chemicals via metabolic engineering. Microbiol Res 2021; 251:126813. [PMID: 34274880 DOI: 10.1016/j.micres.2021.126813] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/28/2021] [Accepted: 07/04/2021] [Indexed: 11/24/2022]
Abstract
Carbon dioxide (CO2) occurs naturally in the atmosphere as a trace gas, which is produced naturally as well as by anthropogenic activities. CO2 is a readily available source of carbon that in principle can be used as a raw material for the synthesis of valuable products. The autotrophic organisms are naturally equipped to convert CO2 into biomass by obtaining energy from sunlight or inorganic electron donors. This autotrophic CO2 fixation has been exploited in biotechnology, and microbial cell factories have been metabolically engineered to convert CO2 into biofuels and other value-added bio-based chemicals. A variety of metabolic engineering efforts for CO2 fixation ranging from basic copy, paste, and fine-tuning approaches to engineering and testing of novel synthetic CO2 fixing pathways have been demonstrated. In this paper, we review the current advances and innovations in metabolic engineering for bio-conversion of CO2 into bio biofuels and other value-added bio-based chemicals.
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11
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Li Z, Xin X, Xiong B, Zhao D, Zhang X, Bi C. Engineering the Calvin-Benson-Bassham cycle and hydrogen utilization pathway of Ralstonia eutropha for improved autotrophic growth and polyhydroxybutyrate production. Microb Cell Fact 2020; 19:228. [PMID: 33308236 PMCID: PMC7733298 DOI: 10.1186/s12934-020-01494-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 12/05/2020] [Indexed: 12/24/2022] Open
Abstract
Background CO2 is fixed by all living organisms with an autotrophic metabolism, among which the Calvin–Benson–Bassham (CBB) cycle is the most important and widespread carbon fixation pathway. Thus, studying and engineering the CBB cycle with the associated energy providing pathways to increase the CO2 fixation efficiency of cells is an important subject of biological research with significant application potential. Results In this work, the autotrophic microbe Ralstonia eutropha (Cupriavidus necator) was selected as a research platform for CBB cycle optimization engineering. By knocking out either CBB operon genes on the operon or mega-plasmid of R. eutropha, we found that both CBB operons were active and contributed almost equally to the carbon fixation process. With similar knock-out experiments, we found both soluble and membrane-bound hydrogenases (SH and MBH), belonging to the energy providing hydrogenase module, were functional during autotrophic growth of R. eutropha. SH played a more significant role. By introducing a heterologous cyanobacterial RuBisCO with the endogenous GroES/EL chaperone system(A quality control systems for proteins consisting of molecular chaperones and proteases, which prevent protein aggregation by either refolding or degrading misfolded proteins) and RbcX(A chaperone in the folding of Rubisco), the culture OD600 of engineered strain increased 89.2% after 72 h of autotrophic growth, although the difference was decreased at 96 h, indicating cyanobacterial RuBisCO with a higher activity was functional in R. eutropha and lead to improved growth in comparison to the host specific enzyme. Meanwhile, expression of hydrogenases was optimized by modulating the expression of MBH and SH, which could further increase the R. eutropha H16 culture OD600 to 93.4% at 72 h. Moreover, the autotrophic yield of its major industrially relevant product, polyhydroxybutyrate (PHB), was increased by 99.7%. Conclusions To our best knowledge, this is the first report of successfully engineering the CBB pathway and hydrogenases of R. eutropha for improved activity, and is one of only a few cases where the efficiency of CO2 assimilation pathway was improved. Our work demonstrates that R. eutropha is a useful platform for studying and engineering the CBB for applications.
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Affiliation(s)
- Zhongkang Li
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Xiuqing Xin
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Bin Xiong
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Dongdong Zhao
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.,Key Laboratory of Systems Microbial Biotechnology, 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, Tianjin, China.
| | - Changhao Bi
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China. .,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
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12
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Breusing C, Mitchell J, Delaney J, Sylva SP, Seewald JS, Girguis PR, Beinart RA. Physiological dynamics of chemosynthetic symbionts in hydrothermal vent snails. ISME JOURNAL 2020; 14:2568-2579. [PMID: 32616905 PMCID: PMC7490688 DOI: 10.1038/s41396-020-0707-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 06/15/2020] [Accepted: 06/23/2020] [Indexed: 12/11/2022]
Abstract
Symbioses between invertebrate animals and chemosynthetic bacteria form the basis of hydrothermal vent ecosystems worldwide. In the Lau Basin, deep-sea vent snails of the genus Alviniconcha associate with either Gammaproteobacteria (A. kojimai, A. strummeri) or Campylobacteria (A. boucheti) that use sulfide and/or hydrogen as energy sources. While the A. boucheti host-symbiont combination (holobiont) dominates at vents with higher concentrations of sulfide and hydrogen, the A. kojimai and A. strummeri holobionts are more abundant at sites with lower concentrations of these reductants. We posit that adaptive differences in symbiont physiology and gene regulation might influence the observed niche partitioning between host taxa. To test this hypothesis, we used high-pressure respirometers to measure symbiont metabolic rates and examine changes in gene expression among holobionts exposed to in situ concentrations of hydrogen (H2: ~25 µM) or hydrogen sulfide (H2S: ~120 µM). The campylobacterial symbiont exhibited the lowest rate of H2S oxidation but the highest rate of H2 oxidation, with fewer transcriptional changes and less carbon fixation relative to the gammaproteobacterial symbionts under each experimental condition. These data reveal potential physiological adaptations among symbiont types, which may account for the observed net differences in metabolic activity and contribute to the observed niche segregation among holobionts.
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Affiliation(s)
- Corinna Breusing
- University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, USA.
| | - Jessica Mitchell
- Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, USA
| | - Jennifer Delaney
- Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, USA
| | - Sean P Sylva
- Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA, USA
| | - Jeffrey S Seewald
- Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA, USA
| | - Peter R Girguis
- Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, USA
| | - Roxanne A Beinart
- University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, USA
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13
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Liu Z, Wang K, Chen Y, Tan T, Nielsen J. Third-generation biorefineries as the means to produce fuels and chemicals from CO2. Nat Catal 2020. [DOI: 10.1038/s41929-019-0421-5] [Citation(s) in RCA: 122] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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14
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Multi-enzyme systems and recombinant cells for synthesis of valuable saccharides: Advances and perspectives. Biotechnol Adv 2019; 37:107406. [DOI: 10.1016/j.biotechadv.2019.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 05/30/2019] [Accepted: 06/08/2019] [Indexed: 02/07/2023]
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15
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Witt A, Pozzi R, Diesch S, Hädicke O, Grammel H. New light on ancient enzymes –
in vitro
CO
2
Fixation by Pyruvate Synthase of
Desulfovibrio africanus
and
Sulfolobus acidocaldarius. FEBS J 2019; 286:4494-4508. [DOI: 10.1111/febs.14981] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/13/2019] [Accepted: 07/02/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Andreas Witt
- Hochschule Biberach University of Applied Science Biberach Germany
| | - Roberta Pozzi
- Hochschule Biberach University of Applied Science Biberach Germany
| | - Stephan Diesch
- Hochschule Biberach University of Applied Science Biberach Germany
| | - Oliver Hädicke
- Max Planck Institute for Dynamics of Complex Technical Systems Magdeburg Germany
| | - Hartmut Grammel
- Hochschule Biberach University of Applied Science Biberach Germany
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16
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Li F, Xie W, Yuan Q, Luo H, Li P, Chen T, Zhao X, Wang Z, Ma H. Genome-scale metabolic model analysis indicates low energy production efficiency in marine ammonia-oxidizing archaea. AMB Express 2018; 8:106. [PMID: 29946801 PMCID: PMC6038301 DOI: 10.1186/s13568-018-0635-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/18/2018] [Indexed: 12/02/2022] Open
Abstract
Marine ammonia-oxidizing archaea (AOA) play an important role in the global nitrogen cycle by obtaining energy for biomass production from CO2 via oxidation of ammonium. The isolation of Candidatus “Nitrosopumilus maritimus” strain SCM1, which represents the globally distributed AOA in the ocean, provided an opportunity for uncovering the contributions of those AOA to carbon and nitrogen cycles in ocean. Although several ammonia oxidation pathways have been proposed for SCM1, little is known about its ATP production efficiency. Here, based on the published genome of Nitrosopumilus maritimus SCM1, a genome-scale metabolic model named NmrFL413 was reconstructed. Based on the model NmrFL413, the estimated ATP/NH4+ yield (0.149–0.276 ATP/NH4+) is tenfold lower than the calculated theoretical yield of the proposed ammonia oxidation pathways in marine AOA (1.5–1.75 ATP/NH4+), indicating a low energy production efficiency of SCM1. Our model also suggested the minor contribution of marine AOA to carbon cycle comparing with their significant contribution to nitrogen cycle in the ocean.
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18
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Kacar B, Hanson‐Smith V, Adam ZR, Boekelheide N. Constraining the timing of the Great Oxidation Event within the Rubisco phylogenetic tree. GEOBIOLOGY 2017; 15:628-640. [PMID: 28670785 PMCID: PMC5575542 DOI: 10.1111/gbi.12243] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 05/09/2017] [Indexed: 05/04/2023]
Abstract
Ribulose 1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBisCO, or Rubisco) catalyzes a key reaction by which inorganic carbon is converted into organic carbon in the metabolism of many aerobic and anaerobic organisms. Across the broader Rubisco protein family, homologs exhibit diverse biochemical characteristics and metabolic functions, but the evolutionary origins of this diversity are unclear. Evidence of the timing of Rubisco family emergence and diversification of its different forms has been obscured by a meager paleontological record of early Earth biota, their subcellular physiology and metabolic components. Here, we use computational models to reconstruct a Rubisco family phylogenetic tree, ancestral amino acid sequences at branching points on the tree, and protein structures for several key ancestors. Analysis of historic substitutions with respect to their structural locations shows that there were distinct periods of amino acid substitution enrichment above background levels near and within its oxygen-sensitive active site and subunit interfaces over the divergence between Form III (associated with anoxia) and Form I (associated with oxia) groups in its evolutionary history. One possible interpretation is that these periods of substitutional enrichment are coincident with oxidative stress exerted by the rise of oxygenic photosynthesis in the Precambrian era. Our interpretation implies that the periods of Rubisco substitutional enrichment inferred near the transition from anaerobic Form III to aerobic Form I ancestral sequences predate the acquisition of Rubisco by fully derived cyanobacterial (i.e., dual photosystem-bearing, oxygen-evolving) clades. The partitioning of extant lineages at high clade levels within our Rubisco phylogeny indicates that horizontal transfer of Rubisco is a relatively infrequent event. Therefore, it is possible that the mutational enrichment periods between the Form III and Form I common ancestral sequences correspond to the adaptation of key oxygen-sensitive components of Rubisco prior to, or coincident with, the Great Oxidation Event.
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Affiliation(s)
- B. Kacar
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeMAUSA
| | - V. Hanson‐Smith
- Department of Microbiology and ImmunologyUniversity of California San FranciscoSan FranciscoCAUSA
| | - Z. R. Adam
- Department of Earth and Planetary SciencesHarvard UniversityCambridgeMAUSA
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Reinforcing carbon fixation: CO 2 reduction replacing and supporting carboxylation. Curr Opin Biotechnol 2017; 49:49-56. [PMID: 28803187 DOI: 10.1016/j.copbio.2017.07.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/18/2017] [Accepted: 07/25/2017] [Indexed: 11/22/2022]
Abstract
Carbon dioxide enters the biosphere via one of two mechanisms: carboxylation, in which CO2 is attached to an existing metabolite, or reduction, in which CO2 is converted to formate or carbon monoxide before further assimilation. Here, we focus on the latter mechanism which usually receives less attention. To better understand the possible advantages of the 'reduction-first' approach, we compare the two general strategies according to the kinetics of the CO2-capturing enzymes, and the resource consumption of the subsequent pathways. We show that the best CO2 reducing enzymes can compete with the best carboxylases. We further demonstrate that pathways that fix CO2 by first reducing it to formate could have an advantage over the majority of their carboxylation-only counterparts in terms of ATP-efficiency and hence biomass yield. We discuss and elaborate on the challenges of implementing 'reduction-first' pathways, including the thermodynamic barrier of CO2 reduction. We believe that pathways based on CO2 reduction are a valuable addition to nature's arsenal for capturing inorganic carbon and could provide promising metabolic solutions that have been previously overlooked.
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20
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Claassens NJ, Sousa DZ, dos Santos VAPM, de Vos WM, van der Oost J. Harnessing the power of microbial autotrophy. Nat Rev Microbiol 2016; 14:692-706. [DOI: 10.1038/nrmicro.2016.130] [Citation(s) in RCA: 150] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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21
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The Cosmic Zoo: The (Near) Inevitability of the Evolution of Complex, Macroscopic Life. Life (Basel) 2016; 6:life6030025. [PMID: 27376334 PMCID: PMC5041001 DOI: 10.3390/life6030025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 06/17/2016] [Accepted: 06/22/2016] [Indexed: 12/31/2022] Open
Abstract
Life on Earth provides a unique biological record from single-cell microbes to technologically intelligent life forms. Our evolution is marked by several major steps or innovations along a path of increasing complexity from microbes to space-faring humans. Here we identify various major key innovations, and use an analytical toolset consisting of a set of models to analyse how likely each key innovation is to occur. Our conclusion is that once the origin of life is accomplished, most of the key innovations can occur rather readily. The conclusion for other worlds is that if the origin of life can occur rather easily, we should live in a cosmic zoo, as the innovations necessary to lead to complex life will occur with high probability given sufficient time and habitat. On the other hand, if the origin of life is rare, then we might live in a rather empty universe.
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Volpers M, Claassens NJ, Noor E, van der Oost J, de Vos WM, Kengen SWM, Martins dos Santos VAP. Integrated In Silico Analysis of Pathway Designs for Synthetic Photo-Electro-Autotrophy. PLoS One 2016; 11:e0157851. [PMID: 27336167 PMCID: PMC4919048 DOI: 10.1371/journal.pone.0157851] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 06/06/2016] [Indexed: 11/22/2022] Open
Abstract
The strong advances in synthetic biology enable the engineering of novel functions and complex biological features in unprecedented ways, such as implementing synthetic autotrophic metabolism into heterotrophic hosts. A key challenge for the sustainable production of fuels and chemicals entails the engineering of synthetic autotrophic organisms that can effectively and efficiently fix carbon dioxide by using sustainable energy sources. This challenge involves the integration of carbon fixation and energy uptake systems. A variety of carbon fixation pathways and several types of photosystems and other energy uptake systems can be chosen and, potentially, modularly combined to design synthetic autotrophic metabolism. Prior to implementation, these designs can be evaluated by the combination of several computational pathway analysis techniques. Here we present a systematic, integrated in silico analysis of photo-electro-autotrophic pathway designs, consisting of natural and synthetic carbon fixation pathways, a proton-pumping rhodopsin photosystem for ATP regeneration and an electron uptake pathway. We integrated Flux Balance Analysis of the heterotrophic chassis Escherichia coli with kinetic pathway analysis and thermodynamic pathway analysis (Max-min Driving Force). The photo-electro-autotrophic designs are predicted to have a limited potential for anaerobic, autotrophic growth of E. coli, given the relatively low ATP regenerating capacity of the proton pumping rhodopsin photosystems and the high ATP maintenance of E. coli. If these factors can be tackled, our analysis indicates the highest growth potential for the natural reductive tricarboxylic acid cycle and the synthetic pyruvate synthase–pyruvate carboxylate -glyoxylate bicycle. Both carbon fixation cycles are very ATP efficient, while maintaining fast kinetics, which also results in relatively low estimated protein costs for these pathways. Furthermore, the synthetic bicycles are highly thermodynamic favorable under conditions analysed. However, the most important challenge identified for improving photo-electro-autotrophic growth is increasing the proton-pumping rate of the rhodopsin photosystems, allowing for higher ATP regeneration. Alternatively, other designs of autotrophy may be considered, therefore the herein presented integrated modeling approach allows synthetic biologists to evaluate and compare complex pathway designs before experimental implementation.
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Affiliation(s)
- Michael Volpers
- Laboratory of Systems and Synthetic Biology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
- LifeGlimmer GmbH, Markelstr. 39a, 12136, Berlin, Germany
| | - Nico J. Claassens
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
| | - Elad Noor
- Institute of Molecular Systems Biology, ETH Zürich, Auguste-Piccard-Hof 1, 8093, Zürich, Switzerland
| | - John van der Oost
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
| | - Willem M. de Vos
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
- Department of Bacteriology and Immunology, Helsinki University, Haartmaninkatu 3, 00014, Helsinki, Finland
| | - Servé W. M. Kengen
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
| | - Vitor A. P. Martins dos Santos
- Laboratory of Systems and Synthetic Biology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands
- LifeGlimmer GmbH, Markelstr. 39a, 12136, Berlin, Germany
- * E-mail:
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Gong F, Liu G, Zhai X, Zhou J, Cai Z, Li Y. Quantitative analysis of an engineered CO2-fixing Escherichia coli reveals great potential of heterotrophic CO2 fixation. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:86. [PMID: 26097503 PMCID: PMC4475311 DOI: 10.1186/s13068-015-0268-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/05/2015] [Indexed: 06/01/2023]
Abstract
BACKGROUND Production of fuels from the abundant and wasteful CO2 is a promising approach to reduce carbon emission and consumption of fossil fuels. Autotrophic microbes naturally assimilate CO2 using energy from light, hydrogen, and/or sulfur. However, their slow growth rates call for investigation of the possibility of heterotrophic CO2 fixation. Although preliminary research has suggested that CO2 fixation in heterotrophic microbes is feasible after incorporation of a CO2-fixing bypass into the central carbon metabolic pathway, it remains unclear how much and how efficient that CO2 can be fixed by a heterotrophic microbe. RESULTS A simple metabolic flux index was developed to indicate the relative strength of the CO2-fixation flux. When two sequential enzymes of the cyanobacterial Calvin cycle were incorporated into an E. coli strain, the flux of the CO2-fixing bypass pathway accounts for 13 % of that of the central carbon metabolic pathway. The value was increased to 17 % when the carbonic anhydrase involved in the cyanobacterial carbon concentrating mechanism was introduced, indicating that low intracellular CO2 concentration is one limiting factor for CO2 fixation in E. coli. The engineered CO2-fixing E. coli with carbonic anhydrase was able to fix CO2 at a rate of 19.6 mg CO2 L(-1) h(-1) or the specific rate of 22.5 mg CO2 g DCW(-1) h(-1). This CO2-fixation rate is comparable with the reported rates of 14 autotrophic cyanobacteria and algae (10.5-147.0 mg CO2 L(-1) h(-1) or the specific rates of 3.5-23.7 mg CO2 g DCW(-1) h(-1)). CONCLUSIONS The ability of CO2 fixation was created and improved in E. coli by incorporating partial cyanobacterial Calvin cycle and carbon concentrating mechanism, respectively. Quantitative analysis revealed that the CO2-fixation rate of this strain is comparable with that of the autotrophic cyanobacteria and algae, demonstrating great potential of heterotrophic CO2 fixation.
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Affiliation(s)
- Fuyu Gong
- />CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road Chaoyang District, Beijing, 100101 China
- />University of the Chinese Academy of Sciences, Beijing, China
| | - Guoxia Liu
- />CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road Chaoyang District, Beijing, 100101 China
| | - Xiaoyun Zhai
- />CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road Chaoyang District, Beijing, 100101 China
- />University of the Chinese Academy of Sciences, Beijing, China
| | - Jie Zhou
- />CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road Chaoyang District, Beijing, 100101 China
| | - Zhen Cai
- />CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road Chaoyang District, Beijing, 100101 China
| | - Yin Li
- />CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road Chaoyang District, Beijing, 100101 China
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Computational protein design enables a novel one-carbon assimilation pathway. Proc Natl Acad Sci U S A 2015; 112:3704-9. [PMID: 25775555 DOI: 10.1073/pnas.1500545112] [Citation(s) in RCA: 212] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We describe a computationally designed enzyme, formolase (FLS), which catalyzes the carboligation of three one-carbon formaldehyde molecules into one three-carbon dihydroxyacetone molecule. The existence of FLS enables the design of a new carbon fixation pathway, the formolase pathway, consisting of a small number of thermodynamically favorable chemical transformations that convert formate into a three-carbon sugar in central metabolism. The formolase pathway is predicted to use carbon more efficiently and with less backward flux than any naturally occurring one-carbon assimilation pathway. When supplemented with enzymes carrying out the other steps in the pathway, FLS converts formate into dihydroxyacetone phosphate and other central metabolites in vitro. These results demonstrate how modern protein engineering and design tools can facilitate the construction of a completely new biosynthetic pathway.
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25
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Payn R, Helton A, Poole G, Izurieta C, Burgin A, Bernhardt E. A generalized optimization model of microbially driven aquatic biogeochemistry based on thermodynamic, kinetic, and stoichiometric ecological theory. Ecol Modell 2014. [DOI: 10.1016/j.ecolmodel.2014.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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26
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Singh J, Pandey P, James D, Chandrasekhar K, Achary VMM, Kaul T, Tripathy BC, Reddy MK. Enhancing C3 photosynthesis: an outlook on feasible interventions for crop improvement. PLANT BIOTECHNOLOGY JOURNAL 2014; 12:1217-30. [PMID: 25196090 DOI: 10.1111/pbi.12246] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 07/14/2014] [Accepted: 07/20/2014] [Indexed: 05/05/2023]
Abstract
Despite the declarations and collective measures taken to eradicate hunger at World Food Summits, food security remains one of the biggest issues that we are faced with. The current scenario could worsen due to the alarming increase in world population, further compounded by adverse climatic conditions, such as increase in atmospheric temperature, unforeseen droughts and decreasing soil moisture, which will decrease crop yield even further. Furthermore, the projected increase in yields of C3 crops as a result of increasing atmospheric CO2 concentrations is much less than anticipated. Thus, there is an urgent need to increase crop productivity beyond existing yield potentials to address the challenge of food security. One of the domains of plant biology that promises hope in overcoming this problem is study of C3 photosynthesis. In this review, we have examined the potential bottlenecks of C3 photosynthesis and the strategies undertaken to overcome them. The targets considered for possible intervention include RuBisCO, RuBisCO activase, Calvin-Benson-Bassham cycle enzymes, CO2 and carbohydrate transport, and light reactions among many others. In addition, other areas which promise scope for improvement of C3 photosynthesis, such as mining natural genetic variations, mathematical modelling for identifying new targets, installing efficient carbon fixation and carbon concentrating mechanisms have been touched upon. Briefly, this review intends to shed light on the recent advances in enhancing C3 photosynthesis for crop improvement.
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Affiliation(s)
- Jitender Singh
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India; School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Fernie AR, Morgan JA. Analysis of metabolic flux using dynamic labelling and metabolic modelling. PLANT, CELL & ENVIRONMENT 2013; 36:1738-1750. [PMID: 23421750 DOI: 10.1111/pce.12083] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/05/2013] [Accepted: 02/11/2013] [Indexed: 06/01/2023]
Abstract
Metabolic fluxes and the capacity to modulate them are a crucial component of the ability of the plant cell to react to environmental perturbations. Our ability to quantify them and to attain information concerning the regulatory mechanisms that control them is therefore essential to understand and influence metabolic networks. For all but the simplest of flux measurements labelling methods have proven to be the most informative. Both steady-state and dynamic labelling approaches have been adopted in the study of plant metabolism. Here the conceptual basis of these complementary approaches, as well as their historical application in microbial, mammalian and plant sciences, is reviewed, and an update on technical developments in label distribution analyses is provided. This is supported by illustrative cases studies involving the kinetic modelling of secondary metabolism. One issue that is particularly complex in the analysis of plant fluxes is the extensive compartmentation of the plant cell. This problem is discussed from both theoretical and experimental perspectives, and the current approaches used to address it are assessed. Finally, current limitations and future perspectives of kinetic modelling of plant metabolism are discussed.
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Affiliation(s)
- A R Fernie
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
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28
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Hawkins AS, McTernan PM, Lian H, Kelly RM, Adams MWW. Biological conversion of carbon dioxide and hydrogen into liquid fuels and industrial chemicals. Curr Opin Biotechnol 2013; 24:376-84. [PMID: 23510698 DOI: 10.1016/j.copbio.2013.02.017] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/18/2013] [Accepted: 02/19/2013] [Indexed: 12/12/2022]
Abstract
Non-photosynthetic routes for biological fixation of carbon dioxide into valuable industrial chemical precursors and fuels are moving from concept to reality. The development of 'electrofuel'-producing microorganisms leverages techniques in synthetic biology, genetic and metabolic engineering, as well as systems-level multi-omic analysis, directed evolution, and in silico modeling. Electrofuel processes are being developed for a range of microorganisms and energy sources (e.g. hydrogen, formate, electricity) to produce a variety of target molecules (e.g. alcohols, terpenes, alkenes). This review examines the current landscape of electrofuel projects with a focus on hydrogen-utilizing organisms covering the biochemistry of hydrogenases and carbonic anhydrases, kinetic and energetic analyses of the known carbon fixation pathways, and the state of genetic systems for current and prospective electrofuel-producing microorganisms.
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Affiliation(s)
- Aaron S Hawkins
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, United States
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Mattozzi MD, Ziesack M, Voges MJ, Silver PA, Way JC. Expression of the sub-pathways of the Chloroflexus aurantiacus 3-hydroxypropionate carbon fixation bicycle in E. coli: Toward horizontal transfer of autotrophic growth. Metab Eng 2013; 16:130-9. [PMID: 23376595 DOI: 10.1016/j.ymben.2013.01.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/08/2013] [Accepted: 01/17/2013] [Indexed: 01/11/2023]
Abstract
The 3-hydroxypropionate (3-HPA) bicycle is unique among CO2-fixing systems in that none of its enzymes appear to be affected by oxygen. Moreover, the bicycle includes a number of enzymes that produce novel intermediates of biotechnological interest, and the CO2-fixing steps in this pathway are relatively rapid. We expressed portions of the 3-HPA bicycle in a heterologous organism, E. coli K12. We subdivided the 3-HPA bicycle into four sub-pathways: (1) synthesis of propionyl-CoA from acetyl-CoA, (2) synthesis of succinate from propionyl-CoA, (3) glyoxylate production and regeneration of acetyl-CoA, and (4) assimilation of glyoxylate and propionyl-CoA to form pyruvate and regenerate acetyl-CoA. We expressed the novel enzymes of the 3-HPA bicycle in operon form and used phenotypic tests for activity. Sub-pathway 1 activated a propionate-specific biosensor. Sub-pathway 2, found in non-CO2-fixing bacteria, was reassembled in E. coli using genes from diverse sources. Sub-pathway 3, operating in reverse, generated succinyl-CoA sufficient to rescue a sucAD(-) double mutant of its diaminopimelic acid (DAP) auxotrophy. Sub-pathway 4 was able to reduce the toxicity of propionate and allow propionate to contribute to cell biomass in a prpC(-)(2 methylcitrate synthase) mutant strain. These results indicate that all of the sub-pathways of the 3-HPA bicycle can function to some extent in vivo in a heterologous organism, as indicated by growth tests. Overexpression of certain enzymes was deleterious to cell growth, and, in particular, expression of MMC-CoA lyase caused a mucoid phenotype. These results have implications for metabolic engineering and for bacterial evolution through horizontal gene transfer.
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Affiliation(s)
- Matthew d Mattozzi
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA.
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30
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Liu P, Jarboe LR. Metabolic engineering of biocatalysts for carboxylic acids production. Comput Struct Biotechnol J 2012; 3:e201210011. [PMID: 24688671 PMCID: PMC3962109 DOI: 10.5936/csbj.201210011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 10/24/2012] [Accepted: 10/29/2012] [Indexed: 11/22/2022] Open
Abstract
Fermentation of renewable feedstocks by microbes to produce sustainable fuels and chemicals has the potential to replace petrochemical-based production. For example, carboxylic acids produced by microbial fermentation can be used to generate primary building blocks of industrial chemicals by either enzymatic or chemical catalysis. In order to achieve the titer, yield and productivity values required for economically viable processes, the carboxylic acid-producing microbes need to be robust and well-performing. Traditional strain development methods based on mutagenesis have proven useful in the selection of desirable microbial behavior, such as robustness and carboxylic acid production. On the other hand, rationally-based metabolic engineering, like genetic manipulation for pathway design, has becoming increasingly important to this field and has been used for the production of several organic acids, such as succinic acid, malic acid and lactic acid. This review investigates recent works on Saccharomyces cerevisiae and Escherichia coli, as well as the strategies to improve tolerance towards these chemicals.
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Affiliation(s)
- Ping Liu
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, USA
| | - Laura R. Jarboe
- Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa, USA
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Autotrophy as a predominant mode of carbon fixation in anaerobic methane-oxidizing microbial communities. Proc Natl Acad Sci U S A 2012; 109:19321-6. [PMID: 23129626 DOI: 10.1073/pnas.1208795109] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The methane-rich, hydrothermally heated sediments of the Guaymas Basin are inhabited by thermophilic microorganisms, including anaerobic methane-oxidizing archaea (mainly ANME-1) and sulfate-reducing bacteria (e.g., HotSeep-1 cluster). We studied the microbial carbon flow in ANME-1/ HotSeep-1 enrichments in stable-isotope-probing experiments with and without methane. The relative incorporation of (13)C from either dissolved inorganic carbon or methane into lipids revealed that methane-oxidizing archaea assimilated primarily inorganic carbon. This assimilation is strongly accelerated in the presence of methane. Experiments with simultaneous amendments of both (13)C-labeled dissolved inorganic carbon and deuterated water provided further insights into production rates of individual lipids derived from members of the methane-oxidizing community as well as their carbon sources used for lipid biosynthesis. In the presence of methane, all prominent lipids carried a dual isotopic signal indicative of their origin from primarily autotrophic microbes. In the absence of methane, archaeal lipid production ceased and bacterial lipid production dropped by 90%; the lipids produced by the residual fraction of the metabolically active bacterial community predominantly carried a heterotrophic signal. Collectively our results strongly suggest that the studied ANME-1 archaea oxidize methane but assimilate inorganic carbon and should thus be classified as methane-oxidizing chemoorganoautotrophs.
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32
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Fast AG, Papoutsakis ET. Stoichiometric and energetic analyses of non-photosynthetic CO2-fixation pathways to support synthetic biology strategies for production of fuels and chemicals. Curr Opin Chem Eng 2012. [DOI: 10.1016/j.coche.2012.07.005] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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33
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Bar-Even A, Noor E, Flamholz A, Milo R. Design and analysis of metabolic pathways supporting formatotrophic growth for electricity-dependent cultivation of microbes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:1039-47. [PMID: 23123556 DOI: 10.1016/j.bbabio.2012.10.013] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/05/2012] [Accepted: 10/25/2012] [Indexed: 11/29/2022]
Abstract
Electrosynthesis is a promising approach that enables the biological production of commodities, like fuels and fine chemicals, using renewably produced electricity. Several techniques have been proposed to mediate the transfer of electrons from the cathode to living cells. Of these, the electroproduction of formate as a mediator seems especially promising: formate is readily soluble, of low toxicity and can be produced at relatively high efficiency and at reasonable current density. While organisms that are capable of formatotrophic growth, i.e. growth on formate, exist naturally, they are generally less suitable for bulk cultivation and industrial needs. Hence, it may be helpful to engineer a model organism of industrial relevance, such as E. coli, for growth on formate. There are numerous metabolic pathways that can potentially support formatotrophic growth. Here we analyze these diverse pathways according to various criteria including biomass yield, thermodynamic favorability, chemical motive force, kinetics and the practical challenges posed by their expression. We find that the reductive glycine pathway, composed of the tetrahydrofolate system, the glycine cleavage system, serine hydroxymethyltransferase and serine deaminase, is a promising candidate to support electrosynthesis in E. coli. The approach presented here exemplifies how combining different computational approaches into a systematic analysis methodology provides assistance in redesigning metabolism. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
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Affiliation(s)
- Arren Bar-Even
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot, Israel.
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Montoya L, Celis LB, Razo-Flores E, Alpuche-Solís ÁG. Distribution of CO2 fixation and acetate mineralization pathways in microorganisms from extremophilic anaerobic biotopes. Extremophiles 2012; 16:805-17. [DOI: 10.1007/s00792-012-0487-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 09/27/2012] [Indexed: 11/28/2022]
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Khunjar WO, Sahin A, West AC, Chandran K, Banta S. Biomass production from electricity using ammonia as an electron carrier in a reverse microbial fuel cell. PLoS One 2012; 7:e44846. [PMID: 23028643 PMCID: PMC3446996 DOI: 10.1371/journal.pone.0044846] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 08/08/2012] [Indexed: 01/23/2023] Open
Abstract
The storage of renewable electrical energy within chemical bonds of biofuels and other chemicals is a route to decreasing petroleum usage. A critical challenge is the efficient transfer of electrons into a biological host that can covert this energy into high energy organic compounds. In this paper, we describe an approach whereby biomass is grown using energy obtained from a soluble mediator that is regenerated electrochemically. The net result is a separate-stage reverse microbial fuel cell (rMFC) that fixes CO₂ into biomass using electrical energy. We selected ammonia as a low cost, abundant, safe, and soluble redox mediator that facilitated energy transfer to biomass. Nitrosomonas europaea, a chemolithoautotroph, was used as the biocatalyst due to its inherent capability to utilize ammonia as its sole energy source for growth. An electrochemical reactor was designed for the regeneration of ammonia from nitrite, and current efficiencies of 100% were achieved. Calculations indicated that overall bioproduction efficiency could approach 2.7±0.2% under optimal electrolysis conditions. The application of chemolithoautotrophy for industrial bioproduction has been largely unexplored, and results suggest that this and related rMFC platforms may enable biofuel and related biochemical production.
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Affiliation(s)
- Wendell O. Khunjar
- Department of Earth and Environmental Engineering, Department of Chemical Engineering, Columbia University, New York, New York, New York, United States of America
| | - Asli Sahin
- Department of Chemical Engineering, Columbia University, New York, New York, New York, United States of America
| | - Alan C. West
- Department of Chemical Engineering, Columbia University, New York, New York, New York, United States of America
- * E-mail: (ACW); (KC); (SB)
| | - Kartik Chandran
- Department of Earth and Environmental Engineering, Department of Chemical Engineering, Columbia University, New York, New York, New York, United States of America
- * E-mail: (ACW); (KC); (SB)
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, New York, New York, New York, United States of America
- * E-mail: (ACW); (KC); (SB)
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Ulas T, Riemer SA, Zaparty M, Siebers B, Schomburg D. Genome-scale reconstruction and analysis of the metabolic network in the hyperthermophilic archaeon Sulfolobus solfataricus. PLoS One 2012; 7:e43401. [PMID: 22952675 PMCID: PMC3432047 DOI: 10.1371/journal.pone.0043401] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 07/20/2012] [Indexed: 12/21/2022] Open
Abstract
We describe the reconstruction of a genome-scale metabolic model of the crenarchaeon Sulfolobus solfataricus, a hyperthermoacidophilic microorganism. It grows in terrestrial volcanic hot springs with growth occurring at pH 2–4 (optimum 3.5) and a temperature of 75–80°C (optimum 80°C). The genome of Sulfolobus solfataricus P2 contains 2,992,245 bp on a single circular chromosome and encodes 2,977 proteins and a number of RNAs. The network comprises 718 metabolic and 58 transport/exchange reactions and 705 unique metabolites, based on the annotated genome and available biochemical data. Using the model in conjunction with constraint-based methods, we simulated the metabolic fluxes induced by different environmental and genetic conditions. The predictions were compared to experimental measurements and phenotypes of S. solfataricus. Furthermore, the performance of the network for 35 different carbon sources known for S. solfataricus from the literature was simulated. Comparing the growth on different carbon sources revealed that glycerol is the carbon source with the highest biomass flux per imported carbon atom (75% higher than glucose). Experimental data was also used to fit the model to phenotypic observations. In addition to the commonly known heterotrophic growth of S. solfataricus, the crenarchaeon is also able to grow autotrophically using the hydroxypropionate-hydroxybutyrate cycle for bicarbonate fixation. We integrated this pathway into our model and compared bicarbonate fixation with growth on glucose as sole carbon source. Finally, we tested the robustness of the metabolism with respect to gene deletions using the method of Minimization of Metabolic Adjustment (MOMA), which predicted that 18% of all possible single gene deletions would be lethal for the organism.
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Affiliation(s)
- Thomas Ulas
- Department of Bioinformatics and Biochemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - S. Alexander Riemer
- Department of Bioinformatics and Biochemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Melanie Zaparty
- Institute for Molecular and Cellular Anatomy, University of Regensburg, Regensburg, Germany
| | - Bettina Siebers
- Faculty of Chemistry, Biofilm Centre, Molecular Enzyme Technology and Biochemistry, University of Duisburg-Essen, Essen, Germany
| | - Dietmar Schomburg
- Department of Bioinformatics and Biochemistry, Technische Universität Braunschweig, Braunschweig, Germany
- * E-mail:
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Production and characterization of poly(3-hydroxypropionate-co-4-hydroxybutyrate) with fully controllable structures by recombinant Escherichia coli containing an engineered pathway. Metab Eng 2012; 14:317-24. [DOI: 10.1016/j.ymben.2012.04.003] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 04/05/2012] [Accepted: 04/16/2012] [Indexed: 11/19/2022]
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Ducat DC, Silver PA. Improving carbon fixation pathways. Curr Opin Chem Biol 2012; 16:337-44. [PMID: 22647231 DOI: 10.1016/j.cbpa.2012.05.002] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/01/2012] [Indexed: 02/07/2023]
Abstract
A recent resurgence in basic and applied research on photosynthesis has been driven in part by recognition that fulfilling future food and energy requirements will necessitate improvements in crop carbon-fixation efficiencies. Photosynthesis in traditional terrestrial crops is being reexamined in light of molecular strategies employed by photosynthetic microbes to enhance the activity of the Calvin cycle. Synthetic biology is well-situated to provide original approaches for compartmentalizing and enhancing photosynthetic reactions in a species independent manner. Furthermore, the elucidation of alternative carbon-fixation routes distinct from the Calvin cycle raises possibilities that novel pathways and organisms can be utilized to fix atmospheric carbon dioxide into useful materials.
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Affiliation(s)
- Daniel C Ducat
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, United States
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Braakman R, Smith E. The emergence and early evolution of biological carbon-fixation. PLoS Comput Biol 2012; 8:e1002455. [PMID: 22536150 PMCID: PMC3334880 DOI: 10.1371/journal.pcbi.1002455] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 02/13/2012] [Indexed: 11/18/2022] Open
Abstract
The fixation of CO₂ into living matter sustains all life on Earth, and embeds the biosphere within geochemistry. The six known chemical pathways used by extant organisms for this function are recognized to have overlaps, but their evolution is incompletely understood. Here we reconstruct the complete early evolutionary history of biological carbon-fixation, relating all modern pathways to a single ancestral form. We find that innovations in carbon-fixation were the foundation for most major early divergences in the tree of life. These findings are based on a novel method that fully integrates metabolic and phylogenetic constraints. Comparing gene-profiles across the metabolic cores of deep-branching organisms and requiring that they are capable of synthesizing all their biomass components leads to the surprising conclusion that the most common form for deep-branching autotrophic carbon-fixation combines two disconnected sub-networks, each supplying carbon to distinct biomass components. One of these is a linear folate-based pathway of CO₂ reduction previously only recognized as a fixation route in the complete Wood-Ljungdahl pathway, but which more generally may exclude the final step of synthesizing acetyl-CoA. Using metabolic constraints we then reconstruct a "phylometabolic" tree with a high degree of parsimony that traces the evolution of complete carbon-fixation pathways, and has a clear structure down to the root. This tree requires few instances of lateral gene transfer or convergence, and instead suggests a simple evolutionary dynamic in which all divergences have primary environmental causes. Energy optimization and oxygen toxicity are the two strongest forces of selection. The root of this tree combines the reductive citric acid cycle and the Wood-Ljungdahl pathway into a single connected network. This linked network lacks the selective optimization of modern fixation pathways but its redundancy leads to a more robust topology, making it more plausible than any modern pathway as a primitive universal ancestral form.
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Affiliation(s)
- Rogier Braakman
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
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Peretó J. Out of fuzzy chemistry: from prebiotic chemistry to metabolic networks. Chem Soc Rev 2012; 41:5394-403. [PMID: 22508108 DOI: 10.1039/c2cs35054h] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The origin of life on Earth was a chemical affair. So how did primitive biochemical systems originate from geochemical and cosmochemical processes on the young planet? Contemporary research into the origins of life subscribes to the Darwinian principle of material causes operating in an evolutionary context, as advocated by A. I. Oparin and J. B. S. Haldane in the 1920s. In its simplest form (e.g., a bacterial cell) extant biological complexity relies on the functional integration of metabolic networks and replicative genomes inside a lipid boundary. Different research programmes have explored the prebiotic plausibility of each of these autocatalytic subsystems and combinations thereof: self-maintained networks of small molecules, template chemistry, and self-reproductive vesicles. This tutorial review focuses on the debates surrounding the origin of metabolism and offers a brief overview of current studies on the evolution of metabolic networks. I suggest that a leitmotif in the origin and evolution of metabolism is the role played by catalysers' substrate ambiguity and multifunctionality.
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Affiliation(s)
- Juli Peretó
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Departament de Bioquímica i Biologia Molecular, Universitat de València, C. Jose Beltran 2, 46980 Paterna, Spain.
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Chen X, Shachar-Hill Y. Insights into metabolic efficiency from flux analysis. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:2343-51. [PMID: 22378949 DOI: 10.1093/jxb/ers057] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The efficiency of carbon and energy flows throughout metabolism defines the potential for growth and reproductive success of plants. Understanding the basis for metabolic efficiency requires relevant definitions of efficiency as well as measurements of biochemical functions through metabolism. Here insights into the basis of efficiency provided by (13)C-based metabolic flux analysis (MFA) as well as the uses and limitations of efficiency in predictive flux balance analysis (FBA) are highlighted. (13)C-MFA studies have revealed unusual features of central metabolism in developing green seeds for the efficient use of light to conserve carbon and identified metabolic inefficiencies in plant metabolism due to dissipation of ATP by substrate cycling. Constraints-based FBA has used efficiency to guide the prediction of the growth and actual internal flux distribution of plant systems. Comparisons in a few cases have been made between flux maps measured by (13)C-based MFA and those predicted by FBA assuming one or more maximal efficiency parameters. These studies suggest that developing plant seeds and photoautotrophic microorganisms may indeed have patterns of metabolic flux that maximize efficiency. MFA and FBA are synergistic toolsets for uncovering and explaining the metabolic basis of efficiencies and inefficiencies in plant systems.
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Affiliation(s)
- Xuewen Chen
- Department of Plant Biology, Michigan State University, East Lansing, MI 48823, USA
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Bar-Even A, Noor E, Milo R. A survey of carbon fixation pathways through a quantitative lens. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:2325-42. [PMID: 22200662 DOI: 10.1093/jxb/err417] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
While the reductive pentose phosphate cycle is responsible for the fixation of most of the carbon in the biosphere, it has several natural substitutes. In fact, due to the characterization of three new carbon fixation pathways in the last decade, the diversity of known metabolic solutions for autotrophic growth has doubled. In this review, the different pathways are analysed and compared according to various criteria, trying to connect each of the different metabolic alternatives to suitable environments or metabolic goals. The different roles of carbon fixation are discussed; in addition to sustaining autotrophic growth it can also be used for energy conservation and as an electron sink for the recycling of reduced electron carriers. Our main focus in this review is on thermodynamic and kinetic aspects, including thermodynamically challenging reactions, the ATP requirement of each pathway, energetic constraints on carbon fixation, and factors that are expected to limit the rate of the pathways. Finally, possible metabolic structures of yet unknown carbon fixation pathways are suggested and discussed.
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Affiliation(s)
- Arren Bar-Even
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
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Raven JA, Giordano M, Beardall J, Maberly SC. Algal evolution in relation to atmospheric CO2: carboxylases, carbon-concentrating mechanisms and carbon oxidation cycles. Philos Trans R Soc Lond B Biol Sci 2012; 367:493-507. [PMID: 22232762 PMCID: PMC3248706 DOI: 10.1098/rstb.2011.0212] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Oxygenic photosynthesis evolved at least 2.4 Ga; all oxygenic organisms use the ribulose bisphosphate carboxylase-oxygenase (Rubisco)-photosynthetic carbon reduction cycle (PCRC) rather than one of the five other known pathways of autotrophic CO(2) assimilation. The high CO(2) and (initially) O(2)-free conditions permitted the use of a Rubisco with a high maximum specific reaction rate. As CO(2) decreased and O(2) increased, Rubisco oxygenase activity increased and 2-phosphoglycolate was produced, with the evolution of pathways recycling this inhibitory product to sugar phosphates. Changed atmospheric composition also selected for Rubiscos with higher CO(2) affinity and CO(2)/O(2) selectivity correlated with decreased CO(2)-saturated catalytic capacity and/or for CO(2)-concentrating mechanisms (CCMs). These changes increase the energy, nitrogen, phosphorus, iron, zinc and manganese cost of producing and operating Rubisco-PCRC, while biosphere oxygenation decreased the availability of nitrogen, phosphorus and iron. The majority of algae today have CCMs; the timing of their origins is unclear. If CCMs evolved in a low-CO(2) episode followed by one or more lengthy high-CO(2) episodes, CCM retention could involve a combination of environmental factors known to favour CCM retention in extant organisms that also occur in a warmer high-CO(2) ocean. More investigations, including studies of genetic adaptation, are needed.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, The James Hutton Institute, University of Dundee at TJHI, Invergowrie, Dundee DD2 5DA, UK.
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Network reduction in metabolic pathway analysis: elucidation of the key pathways involved in the photoautotrophic growth of the green alga Chlamydomonas reinhardtii. Metab Eng 2012; 14:458-67. [PMID: 22342232 DOI: 10.1016/j.ymben.2012.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 01/13/2012] [Accepted: 01/31/2012] [Indexed: 11/21/2022]
Abstract
Metabolic pathway analysis aims at discovering and analyzing meaningful routes and their interactions in metabolic networks. A major difficulty in applying this technique lies in the decomposition of metabolic flux distributions into elementary mode or extreme pathway activity patterns, which in general is not unique. We propose a network reduction approach based on the decomposition of a set of flux vectors representing adaptive microbial metabolic behavior in bioreactors into a minimal set of shared pathways. Several optimality criteria from the literature were compared in order to select the most appropriate objective function. We further analyze photoautotrophic metabolism of the green alga Chlamydomonas reinhardtii growing in a photobioreactor under maximal growth rate conditions. Key pathways involved in its adaptive metabolic response to changes in light influx are identified and discussed using an energetic approach.
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Abstract
Carboxylases are among the most important enzymes in the biosphere, because they catalyze a key reaction in the global carbon cycle: the fixation of inorganic carbon (CO₂). This minireview discusses the physiological roles of carboxylases in different microbial pathways that range from autotrophy, carbon assimilation, and anaplerosis to biosynthetic and redox-balancing functions. In addition, the current and possible future uses of carboxylation reactions in synthetic biology are discussed. Such uses include the possible transformation of the greenhouse gas carbon dioxide into value-added compounds and the production of novel antibiotics.
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Sweetlove LJ, Ratcliffe RG. Flux-balance modeling of plant metabolism. FRONTIERS IN PLANT SCIENCE 2011; 2:38. [PMID: 22645533 PMCID: PMC3355794 DOI: 10.3389/fpls.2011.00038] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 07/28/2011] [Indexed: 05/17/2023]
Abstract
Flux-balance modeling of plant metabolic networks provides an important complement to (13)C-based metabolic flux analysis. Flux-balance modeling is a constraints-based approach in which steady-state fluxes in a metabolic network are predicted by using optimization algorithms within an experimentally bounded solution space. In the last 2 years several flux-balance models of plant metabolism have been published including genome-scale models of Arabidopsis metabolism. In this review we consider what has been learnt from these models. In addition, we consider the limitations of flux-balance modeling and identify the main challenges to generating improved and more detailed models of plant metabolism at tissue- and cell-specific scales. Finally we discuss the types of question that flux-balance modeling is well suited to address and its potential role in metabolic engineering and crop improvement.
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