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Karnamkkott HS, Das S, Mondal T, Mondal KC. Small molecule activation by sila/germa boryne species. J Comput Chem 2024; 45:804-819. [PMID: 38135467 DOI: 10.1002/jcc.27275] [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: 09/21/2023] [Revised: 11/19/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023]
Abstract
The inability of p-block elements to participate in π-backbonding restricts them from activating small molecules like CO, H2 , and so forth. However, the development of the main group metallomimetics became a new pathway, where the main-group elements like boron can bind and activate small molecules like CO and H2 . The concept of the frustrated Lewis pair, Boron-Boron multiple bonds, and borylene are previously illustrated. Some of these reported classes of boron species can mimic the jobs of the metal complexes. Hence, we have theoretically studied the binding of CO/N2 molecules at B-center of elusive species like sila/germa boryne stabilized by donor base ligands (cAAC)BE(Me)(L), where E Si, L cAACMe , NHCMe , PMe3 , E Ge, L cAACMe and (NHCMe )BE(Me)(cAACMe )). The substitutional analogues of (cAACR )BSiR1 (cAAC) and E P, L cAACMe ) have been studied by density functional theory (DFT), natural bond orbital, QTAIM calculations and energy decomposition analysis (EDA) coupled with natural orbital for chemical valence (NOCV) analyses. The computed bond dissociation energy and inner stability analyses by the EDA-NOCV method showed that the CO molecule can bind at the B-center of the above-mentioned species due to stronger σ-donor ability while binding of N2 has been theoretically predicted to be weak. The energy barrier for the CO binding is estimated to be 13-14 kcal/mol by transition state calculation. The change of partial triple bond character to single bond nature of the BSi bond and the bending of CBSi bond angle of sila-boryne species are the reason for the activation energy. Our study reveals the ability of such species to bind and activate the CO molecule to mimic the transition metal-containing complexes. We have additionally shown that binding of Fe(CO)4 and Ni(CO)3 is feasible at Si-center after binding of CO at the B-center.
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Affiliation(s)
| | - Sujit Das
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, India
| | - Totan Mondal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, India
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2
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Martínez-Ruano JA, Suazo A, Véliz F, Otalora F, Conejeros R, González E, Aroca G. Effect of pH on metabolic pathway shift in fermentation and electro-fermentation of xylose by Clostridium autoethanogenum. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119918. [PMID: 38154218 DOI: 10.1016/j.jenvman.2023.119918] [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: 09/29/2023] [Revised: 12/06/2023] [Accepted: 12/17/2023] [Indexed: 12/30/2023]
Abstract
Clostridium autoethanogenum can to convert waste gases (CO2, CO, H2) and xylose from hydrolyzed biomass into acetate, lactate, formate, ethanol and 2,3-butanediol, being a candidate for the transformation of waste streams of lignocellulosic biorefineries. Electro-fermentation (EF) modify the pattern of traditional fermentations resulting in improved product yields as has been shown when using Clostridium strains. The aim of this work was to evaluate the influence of pH on microbial growth and product distribution during fermentation and EF of xylose by C. autoethanogenum DSM10061. Fermentation and EF were carried out in a H-type reactor at three controlled pH: 5.0, 5.5 and 5.8, and at a fixed potential of -600 mV (versus Ag/AgCl) in the EF. The experiments showed that maximum biomass concentration increased as the pH increased in fermentation and EF. In accordance with maximum biomass reached, the highest substrate conversion was observed at pH 5.8 for both systems, with 76.80 % in fermentation and 96.18 % in EF. Moreover, the highest concentrations of acetic acid (1.41 ± 0.07 g L-1) and ethanol (1.45 ± 0.15 g L-1) were obtained at the end of cultures in the EF at pH 5.8. The production of lactic and formic acid decreased by the application of the external potential regardless of the pH value, reaching the lowest productivity at pH 5.8. In contrast, the specific productivity of acetic acid and ethanol was lower in both fermentation and EF at the lowest pH. Furthermore, the presence of 0.06 g L-1 of 2,3-butanediol was only detected in EF at pH 5.8. The results revealed that EF modulated microbial metabolism, which can be explained by a possible increased generation of NADP+/NADPH cofactors, which would redirect the metabolic pathway to more reduced products.
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Affiliation(s)
| | - Andrés Suazo
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Fabián Véliz
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Fabián Otalora
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Raúl Conejeros
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile
| | - Ernesto González
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile; Department of Chemical and Materials Engineering, Faculty of Chemical Sciences, Universidad Complutense de Madrid, Spain
| | - Germán Aroca
- School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Chile.
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3
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Seo WW, Yim JH, Lim JS, Choi KY. Liquid-liquid equilibrium (LLE) data of ternary mixtures of [water+acetic acid+1-nonanol] and [water+acetic acid+1-decanol] at 298.2–318.2 K and 101.3 kPa. KOREAN J CHEM ENG 2022. [DOI: 10.1007/s11814-022-1196-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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An T, Kim YK. Effect of selenium and tungsten on cell growth and metabolite production in syngas fermentation using "Clostridium autoethanogenum". J Biotechnol 2022; 356:60-64. [PMID: 35878811 DOI: 10.1016/j.jbiotec.2022.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 06/16/2022] [Accepted: 07/20/2022] [Indexed: 11/18/2022]
Abstract
The effect of tungsten and selenium on cell growth and production of metabolites such as acetic acid and ethanol when fermenting syngas using "Clostridium autoethanogenum" was investigated to improve the process efficiency. General concentrations of selenium and tungsten in the medium are 0.01µM during acetogenic syngas fermentation. We conducted culture experiments at concentrations of 0, 0.001, 0.01 and 0.1µM for each heavy metal. The effect of selenium on cell growth and total metabolite production was greater than that of tungsten as the effect of selenium on formate dehydrogenase, an important enzyme of the Wood-Ljungdahl pathway, is greater than that of tungsten. Although an increase in tungsten had a marginal effect on total metabolite production, the ethanol/acetic acid production ratio increased significantly due to a decrease in acetic acid and an increase in ethanol production. Thus, tungsten plays a key role in activating aldehyde:ferredoxin oxidoreductase, a key enzyme in the reduction of acetate to ethanol. A specific ethanol productivity of 0.462g ethanol/g DCW∙d was obtained in a culture using 0.01µM selenium and 0.1µM tungsten, which was 2.18 times higher than when using 0.01µM of both selenium and tungsten.
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Affiliation(s)
- Taegwang An
- Department of Chemical Engineering, Research Center of Chemical Technology, Hankyong National University, Anseong, Gyeonggi-do 17579, Republic of Korea
| | - Young-Kee Kim
- Department of Chemical Engineering, Research Center of Chemical Technology, Hankyong National University, Anseong, Gyeonggi-do 17579, Republic of Korea.
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5
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He Y, Lens PNL, Veiga MC, Kennes C. Selective butanol production from carbon monoxide by an enriched anaerobic culture. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150579. [PMID: 34582872 DOI: 10.1016/j.scitotenv.2021.150579] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/21/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
An anaerobic mixed culture able to grow on pure carbon monoxide (CO) as well as syngas (CO, CO2 and H2), that produced unusual high concentrations of butanol, was enriched in a bioreactor with intermittent CO gas feeding. At pH 6.2, it mainly produced acids, generally acetic and butyric acid. After adaptation, under stress conditions of CO exposure at a partial pressure of 1.8 bar and low pH (e.g., 5.7), the enrichment accumulated ethanol, but also high amounts of butanol, up to 6.8 g/L, never reported before, with a high butanol/butyric acid molar ratio of 12.6, highlighting the high level of acid to alcohol conversion. At the end of the assay, both the acetic acid and ethanol concentrations decreased, with concomitant butyric acid production, suggesting C2 to C4 acid bioconversion, though this was not a dominant bioconversion process. The reverse reaction of ethanol oxidation to acetic acid was observed in the presence of CO2 produced during CO fermentation. Interestingly, butanol oxidation with simultaneous butyric acid production occurred upon production of CO2 from CO, which has to the best of our knowledge never been reported. Although the sludge inoculum contained a few known solventogenic Clostridia, the relative taxonomic abundance of the enriched sludge was diverse in Clostridia and Bacilli classes, containing known solventogens, e.g., Clostridium ljungdhalii, Clostridium ragsdalei and Clostridium coskatii, confirming their efficient enrichment. The relative abundance of unassigned Clostridium species amounted to 27% with presumably novel ethanol/butanol producers.
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Affiliation(s)
- Yaxue He
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain; National University of Ireland Galway, H91 TK33 Galway, Ireland
| | - Piet N L Lens
- National University of Ireland Galway, H91 TK33 Galway, Ireland
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain.
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Ayol A, Peixoto L, Keskin T, Abubackar HN. Reactor Designs and Configurations for Biological and Bioelectrochemical C1 Gas Conversion: A Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182111683. [PMID: 34770196 PMCID: PMC8583215 DOI: 10.3390/ijerph182111683] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/22/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022]
Abstract
Microbial C1 gas conversion technologies have developed into a potentially promising technology for converting waste gases (CO2, CO) into chemicals, fuels, and other materials. However, the mass transfer constraint of these poorly soluble substrates to microorganisms is an important challenge to maximize the efficiencies of the processes. These technologies have attracted significant scientific interest in recent years, and many reactor designs have been explored. Syngas fermentation and hydrogenotrophic methanation use molecular hydrogen as an electron donor. Furthermore, the sequestration of CO2 and the generation of valuable chemicals through the application of a biocathode in bioelectrochemical cells have been evaluated for their great potential to contribute to sustainability. Through a process termed microbial chain elongation, the product portfolio from C1 gas conversion may be expanded further by carefully driving microorganisms to perform acetogenesis, solventogenesis, and reverse β-oxidation. The purpose of this review is to provide an overview of the various kinds of bioreactors that are employed in these microbial C1 conversion processes.
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Affiliation(s)
- Azize Ayol
- Department of Environmental Engineering, Dokuz Eylul University, Izmir 35390, Turkey;
| | - Luciana Peixoto
- Centre of Biological Engineering (CEB), University of Minho, 4710-057 Braga, Portugal;
| | - Tugba Keskin
- Department of Environmental Protection Technologies, Izmir Democracy University, Izmir 35140, Turkey;
| | - Haris Nalakath Abubackar
- Chemical Engineering Laboratory, BIOENGIN Group, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of A Coruña, 15008 A Coruña, Spain
- Correspondence:
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Nissen LS, Basen M. The emerging role of aldehyde:ferredoxin oxidoreductases in microbially-catalyzed alcohol production. J Biotechnol 2019; 306:105-117. [DOI: 10.1016/j.jbiotec.2019.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 11/16/2022]
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8
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Greene J, Daniell J, Köpke M, Broadbelt L, Tyo KE. Kinetic ensemble model of gas fermenting Clostridium autoethanogenum for improved ethanol production. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.04.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Kang H, Park B, Bolo NR, Pathiraja D, Park S, Cha M, Choi IG, Chang IS. Gene-Centric Metagenome Analysis Reveals Gene Clusters for Carbon Monoxide Conversion and Validates Isolation of a Clostridial Acetogen for C2 Chemical Production. Biotechnol J 2019; 14:e1800471. [PMID: 30802355 DOI: 10.1002/biot.201800471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/29/2018] [Indexed: 11/05/2022]
Abstract
Syngas fermentation is largely dependent on acetogens that occur in various anaerobic environmental samples including soil, sediment, and feces. Here the authors report the metagenomic isolation of acetogens for C2 chemical production from syngas. Screening acetogens for C2 chemical production typically involves detecting the presence of the Wood-Ljungdahl Pathway for carbon monoxide conversion. The authors collect samples from river-bed sediments potentially having conditions suitable for carbon monoxide-converting anaerobes, and enrich the samples under carbon monoxide selection pressure. Changes in the microbial community during the experimental procedure are investigated using both amplicon and shotgun metagenome sequencing. Combined next-generation sequencing techniques enabl in situ tracking of the major acetogenic bacterial group and lead to the discovery of a 16 kb of gene cluster for WLP. The authors isolat an acetogenic clostridial strain from the enrichment culture (strain H21-9). The functional activity of H21-9 is confirmed by its high level of production of C2 chemicals from carbon monoxide (77.4 mM acetate and 2.5 mM of ethanol). This approach of incorporating experimental enrichment with metagenomic analysis can facilitate the discovery of novel strains from environmental habitats by tracking target strains during the screening process, combined with validation of their functional activity.
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Affiliation(s)
- Hyunsoo Kang
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Byeonghyeok Park
- School of Life Sciences and Biotechnology Korea University, 5 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Nicole R Bolo
- International Environmental Research Institute Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Duleepa Pathiraja
- School of Life Sciences and Biotechnology Korea University, 5 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Shinyoung Park
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Minseok Cha
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - In-Geol Choi
- School of Life Sciences and Biotechnology Korea University, 5 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - In Seop Chang
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea
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Liebal UW, Blank LM, Ebert BE. CO 2 to succinic acid - Estimating the potential of biocatalytic routes. Metab Eng Commun 2018; 7:e00075. [PMID: 30197864 PMCID: PMC6127376 DOI: 10.1016/j.mec.2018.e00075] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/07/2018] [Accepted: 06/25/2018] [Indexed: 11/26/2022] Open
Abstract
Microbial carbon dioxide assimilation and conversion to chemical platform molecules has the potential to be developed as economic, sustainable processes. The carbon dioxide assimilation can proceed by a variety of natural pathways and recently even synthetic CO2 fixation routes have been designed. Early assessment of the performance of the different carbon fixation alternatives within biotechnological processes is desirable to evaluate their potential. Here we applied stoichiometric metabolic modeling based on physiological and process data to evaluate different process variants for the conversion of C1 carbon compounds to the industrial relevant platform chemical succinic acid. We computationally analyzed the performance of cyanobacteria, acetogens, methylotrophs, and synthetic CO2 fixation pathways in Saccharomyces cerevisiae in terms of production rates, product yields, and the optimization potential. This analysis provided insight into the economic feasibility and allowed to estimate the future industrial applicability by estimating overall production costs. With reported, or estimated data of engineered or wild type strains, none of the simulated microbial succinate production processes showed a performance allowing competitive production. The main limiting factors were identified as gas and photon transfer and metabolic activities whereas metabolic network structure was not restricting. In simulations with optimized parameters most process alternatives reached economically interesting values, hence, represent promising alternatives to sugar-based fermentations.
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Affiliation(s)
| | - Lars M. Blank
- Institute of Applied Microbiology-iAMB, Aachen Biology and Biotechnology-ABBt, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany
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11
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Enhanced enzymatic hydrolysis of wheat straw by two-step pretreatment combining alkalization and adsorption. Appl Microbiol Biotechnol 2018; 102:9831-9842. [DOI: 10.1007/s00253-018-9335-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/12/2018] [Accepted: 08/16/2018] [Indexed: 12/31/2022]
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Lagoa-Costa B, Abubackar HN, Fernández-Romasanta M, Kennes C, Veiga MC. Integrated bioconversion of syngas into bioethanol and biopolymers. BIORESOURCE TECHNOLOGY 2017; 239:244-249. [PMID: 28521235 DOI: 10.1016/j.biortech.2017.05.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 06/07/2023]
Abstract
Syngas bioconversion is a promising method for bioethanol production, but some VFA remains at the end of fermentation. A two-stage process was set-up, including syngas fermentation as first stage under strict anaerobic conditions using C. autoethanogenum as inoculum, with syngas (CO/CO2/H2/N2, 30/10/20/40) as gaseous substrate. The second stage consisted in various fed-batch assays using a highly enriched PHA accumulating biomass as inoculum, where the potential for biopolymer production from the remaining acetic acid at the end of the syngas fermentation was evaluated. All of the acetic acid was consumed and accumulated as biopolymer, while ethanol and 2,3-butanediol remained basically unused. It can be concluded that a high C/N ratio in the effluent from the syngas fermentation stage was responsible for non-consumption of alcohols. A maximum PHA content of 24% was reached at the end of the assay.
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Affiliation(s)
- Borja Lagoa-Costa
- Chemical Engineering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 A Coruña, Spain
| | - Haris Nalakath Abubackar
- Chemical Engineering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 A Coruña, Spain
| | - María Fernández-Romasanta
- Chemical Engineering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 A Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 A Coruña, Spain
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of La Coruña, Rúa da Fraga 10, E - 15008 A Coruña, Spain.
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De Tissera S, Köpke M, Simpson SD, Humphreys C, Minton NP, Dürre P. Syngas Biorefinery and Syngas Utilization. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2017. [DOI: 10.1007/10_2017_5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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14
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Valgepea K, Loi KQ, Behrendorff JB, Lemgruber RDSP, Plan M, Hodson MP, Köpke M, Nielsen LK, Marcellin E. Arginine deiminase pathway provides ATP and boosts growth of the gas-fermenting acetogen Clostridium autoethanogenum. Metab Eng 2017; 41:202-211. [PMID: 28442386 DOI: 10.1016/j.ymben.2017.04.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 03/10/2017] [Accepted: 04/20/2017] [Indexed: 12/20/2022]
Abstract
Acetogens are attractive organisms for the production of chemicals and fuels from inexpensive and non-food feedstocks such as syngas (CO, CO2 and H2). Expanding their product spectrum beyond native compounds is dictated by energetics, particularly ATP availability. Acetogens have evolved sophisticated strategies to conserve energy from reduction potential differences between major redox couples, however, this coupling is sensitive to small changes in thermodynamic equilibria. To accelerate the development of strains for energy-intensive products from gases, we used a genome-scale metabolic model (GEM) to explore alternative ATP-generating pathways in the gas-fermenting acetogen Clostridium autoethanogenum. Shadow price analysis revealed a preference of C. autoethanogenum for nine amino acids. This prediction was experimentally confirmed under heterotrophic conditions. Subsequent in silico simulations identified arginine (ARG) as a key enhancer for growth. Predictions were experimentally validated, and faster growth was measured in media containing ARG (tD~4h) compared to growth on yeast extract (tD~9h). The growth-boosting effect of ARG was confirmed during autotrophic growth. Metabolic modelling and experiments showed that acetate production is nearly abolished and fast growth is realised by a three-fold increase in ATP production through the arginine deiminase (ADI) pathway. The involvement of the ADI pathway was confirmed by metabolomics and RNA-sequencing which revealed a ~500-fold up-regulation of the ADI pathway with an unexpected down-regulation of the Wood-Ljungdahl pathway. The data presented here offer a potential route for supplying cells with ATP, while demonstrating the usefulness of metabolic modelling for the discovery of native pathways for stimulating growth or enhancing energy availability.
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Affiliation(s)
- Kaspar Valgepea
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia
| | - Kim Q Loi
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia
| | | | - Renato de S P Lemgruber
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia
| | - Manuel Plan
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia; Metabolomics Australia, AIBN, The University of Queensland, Brisbane, Australia
| | - Mark P Hodson
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia; Metabolomics Australia, AIBN, The University of Queensland, Brisbane, Australia; School of Pharmacy, The University of Queensland, Brisbane, Australia
| | | | - Lars K Nielsen
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia
| | - Esteban Marcellin
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Australia.
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15
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Liew F, Martin ME, Tappel RC, Heijstra BD, Mihalcea C, Köpke M. Gas Fermentation-A Flexible Platform for Commercial Scale Production of Low-Carbon-Fuels and Chemicals from Waste and Renewable Feedstocks. Front Microbiol 2016; 7:694. [PMID: 27242719 PMCID: PMC4862988 DOI: 10.3389/fmicb.2016.00694] [Citation(s) in RCA: 206] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/26/2016] [Indexed: 12/13/2022] Open
Abstract
There is an immediate need to drastically reduce the emissions associated with global fossil fuel consumption in order to limit climate change. However, carbon-based materials, chemicals, and transportation fuels are predominantly made from fossil sources and currently there is no alternative source available to adequately displace them. Gas-fermenting microorganisms that fix carbon dioxide (CO2) and carbon monoxide (CO) can break this dependence as they are capable of converting gaseous carbon to fuels and chemicals. As such, the technology can utilize a wide range of feedstocks including gasified organic matter of any sort (e.g., municipal solid waste, industrial waste, biomass, and agricultural waste residues) or industrial off-gases (e.g., from steel mills or processing plants). Gas fermentation has matured to the point that large-scale production of ethanol from gas has been demonstrated by two companies. This review gives an overview of the gas fermentation process, focusing specifically on anaerobic acetogens. Applications of synthetic biology and coupling gas fermentation to additional processes are discussed in detail. Both of these strategies, demonstrated at bench-scale, have abundant potential to rapidly expand the commercial product spectrum of gas fermentation and further improve efficiencies and yields.
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16
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Abubackar HN, Veiga MC, Kennes C. Carbon monoxide fermentation to ethanol by Clostridium autoethanogenum in a bioreactor with no accumulation of acetic acid. BIORESOURCE TECHNOLOGY 2015; 186:122-127. [PMID: 25812815 DOI: 10.1016/j.biortech.2015.02.113] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 05/24/2023]
Abstract
Fermentation of CO or syngas offers an attractive route to produce bioethanol. However, during the bioconversion, one of the challenges to overcome is to reduce the production of acetic acid in order to minimize recovery costs. Different experiments were done with Clostridium autoethanogenum. With the addition of 0.75 μM tungsten, ethanol production from carbon monoxide increased by about 128% compared to the control, without such addition, in batch mode. In bioreactors with continuous carbon monoxide supply, the maximum biomass concentration reached at pH 6.0 was 109% higher than the maximum achieved at pH 4.75 but, interestingly, at pH 4.75, no acetic acid was produced and the ethanol titer reached a maximum of 867 mg/L with minor amounts of 2,3-butanediol (46 mg/L). At the higher pH studied (pH 6.0) in the continuous gas-fed bioreactor, almost equal amounts of ethanol and acetic acid were formed, reaching 907.72 mg/L and 910.69 mg/L respectively.
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Affiliation(s)
- Haris Nalakath Abubackar
- Chemical Engineering Laboratory, Faculty of Sciences, University of La Coruña, Rúa da Fraga 10, 15008 La Coruña, Spain
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences, University of La Coruña, Rúa da Fraga 10, 15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences, University of La Coruña, Rúa da Fraga 10, 15008 La Coruña, Spain.
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