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Zhang JZ, Li YZ, Xi ZN, Gao HP, Zhang Q, Liu LC, Li FL, Ma XQ. Engineered acetogenic bacteria as microbial cell factory for diversified biochemicals. Front Bioeng Biotechnol 2024; 12:1395540. [PMID: 39055341 PMCID: PMC11269201 DOI: 10.3389/fbioe.2024.1395540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 06/28/2024] [Indexed: 07/27/2024] Open
Abstract
Acetogenic bacteria (acetogens) are a class of microorganisms with conserved Wood-Ljungdahl pathway that can utilize CO and CO2/H2 as carbon source for autotrophic growth and convert these substrates to acetate and ethanol. Acetogens have great potential for the sustainable production of biofuels and bulk biochemicals using C1 gases (CO and CO2) from industrial syngas and waste gases, which play an important role in achieving carbon neutrality. In recent years, with the development and improvement of gene editing methods, the metabolic engineering of acetogens is making rapid progress. With introduction of heterogeneous metabolic pathways, acetogens can improve the production capacity of native products or obtain the ability to synthesize non-native products. This paper reviews the recent application of metabolic engineering in acetogens. In addition, the challenges of metabolic engineering in acetogens are indicated, and strategies to address these challenges are also discussed.
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Affiliation(s)
- Jun-Zhe Zhang
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yu-Zhen Li
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhi-Ning Xi
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Hui-Peng Gao
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Quan Zhang
- Sinopec Dalian (Fushun) Research Institute of Petroleum and Petrochemicals, Dalian, China
| | - Li-Cheng Liu
- Key Laboratory of Marine Chemistry Theory and Technology (Ministry of Education), College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China
| | - Fu-Li Li
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Shandong Energy Institute, Qingdao, China
- Qingdao New Energy Shandong Laboratory, Qingdao, China
| | - Xiao-Qing Ma
- Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
- Qingdao New Energy Shandong Laboratory, Qingdao, China
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Feng J, Wang Q, Qin Z, Guo X, Fu H, Yang ST, Wang J. Development of inducible promoters for regulating gene expression in Clostridium tyrobutyricum for biobutanol production. Biotechnol Bioeng 2024; 121:1518-1531. [PMID: 38548678 DOI: 10.1002/bit.28701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/29/2023] [Accepted: 01/03/2024] [Indexed: 04/14/2024]
Abstract
Clostridium tyrobutyricum is an anaerobe known for its ability to produce short-chain fatty acids, alcohols, and esters. We aimed to develop inducible promoters for fine-tuning gene expression in C. tyrobutyricum. Synthetic inducible promoters were created by employing an Escherichia coli lac operator to regulate the thiolase promoter (PCathl) from Clostridium acetobutylicum, with the best one (LacI-Pto4s) showing a 5.86-fold dynamic range with isopropyl β- d-thiogalactoside (IPTG) induction. A LT-Pt7 system with a dynamic range of 11.6-fold was then created by combining LacI-Pto4s with a T7 expression system composing of RNA polymerase (T7RNAP) and Pt7lac promoter. Furthermore, two inducible expression systems BgaR-PbgaLA and BgaR-PbgaLB with a dynamic range of ~40-fold were developed by optimizing a lactose-inducible expression system from Clostridium perfringens with modified 5' untranslated region (5' UTR) and ribosome-binding site (RBS). BgaR-PbgaLB was then used to regulate the expressions of a bifunctional aldehyde/alcohol dehydrogenase encoded by adhE2 and butyryl-CoA/acetate Co-A transferase encoded by cat1 in C. tyrobutyricum wild type and Δcat1::adhE2, respectively, demonstrating its efficient inducible gene regulation. The regulated cat1 expression also confirmed that the Cat1-catalyzed reaction was responsible for acetate assimilation in C. tyrobutyricum. The inducible promoters offer new tools for tuning gene expression in C. tyrobutyricum for industrial applications.
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Affiliation(s)
- Jun Feng
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Qingke Wang
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Zhen Qin
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Xiaolong Guo
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Hongxin Fu
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Shang-Tian Yang
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou, China
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Tremblay PL, Zhang T. Genetic tools for the electrotroph Sporomusa ovata and autotrophic biosynthesis. Appl Environ Microbiol 2024; 90:e0175723. [PMID: 38117058 PMCID: PMC10807461 DOI: 10.1128/aem.01757-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/13/2023] [Indexed: 12/21/2023] Open
Abstract
Sporomusa ovata is a Gram-negative acetogen of the Sporomusaceae family with a unique physiology. This anerobic bacterium is a core microbial catalyst for advanced CO2-based biotechnologies including gas fermentation, microbial electrosynthesis, and hybrid photosystem. Until now, no genetic tools exist for S. ovata, which is a critical obstacle to its optimization as an autotrophic chassis and the acquisition of knowledge about its metabolic capacities. Here, we developed an electroporation protocol for S. ovata. With this procedure, it became possible to introduce replicative plasmids such as pJIR751 and its derivatives into the acetogen. This system was then employed to demonstrate the feasibility of heterologous expression by introducing a functional β-glucuronidase enzyme under the promoters of different strengths in S. ovata. Next, a recombinant S. ovata strain producing the non-native product acetone both from an organic carbon substrate and from CO2 was constructed. Finally, a replicative plasmid capable of integrating itself on the chromosome of the acetogen was developed as a tool for genome editing, and gene deletion was demonstrated. These results indicate that S. ovata can be engineered and provides a first-generation genetic toolbox for the optimization of this biotechnological workhorse.IMPORTANCES. ovata harbors unique features that make it outperform most microbes for autotrophic biotechnologies such as a capacity to acquire electrons from different solid donors, a low H2 threshold, and efficient energy conservation mechanisms. The development of the first-generation genetic instruments described in this study is a key step toward understanding the molecular mechanisms involved in these outstanding metabolic and physiological characteristics. In addition, these tools enable the construction of recombinant S. ovata strains that can synthesize a wider range of products in an efficient manner.
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Affiliation(s)
- Pier-Luc Tremblay
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan, China
- Institut WUT-AMU, Wuhan University of Technology, Wuhan, China
- Shaoxing Institute for Advanced Research, Wuhan University of Technology, Shaoxing, China
- Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, China
| | - Tian Zhang
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan, China
- Institut WUT-AMU, Wuhan University of Technology, Wuhan, China
- Shaoxing Institute for Advanced Research, Wuhan University of Technology, Shaoxing, China
- Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, China
- Advanced Engineering Technology Research Institute of Zhongshan City, Wuhan University of Technology, Zhongshan, China
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Ma Y, Guo N, Li X, Jiang Z, Zhang D, Guo L, Wang Y. Development of an Efficient Recombinant Protein Expression System in Clostridium saccharoperbutylacetonicum Based on the Bacteriophage T7 System. ACS Synth Biol 2023; 12:3092-3105. [PMID: 37712503 DOI: 10.1021/acssynbio.3c00439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
Recombinant proteins have broad applications. However, there is a lack of a recombinant protein expression system specifically for large-scale production in anaerobic hosts. Here, we developed a powerful and stringently inducible protein expression system based on the bacteriophage T7 system in the strictly anaerobic solvent-producing Clostridium saccharoperbutylacetonicum. With the integration of a codon optimized T7 RNA polymerase into the chromosome, a single plasmid carrying a T7 promoter could efficiently drive high-level expression of the target gene in an orthogonal manner, which was tightly regulated by a lactose-inducible system. Furthermore, by deleting beta-galactosidase genes involved in lactose metabolism, the transcriptional strength was further improved. In the ultimately optimized strain TM-07, the transcriptional strength of the T7 promoter showed 9.5-fold increase compared to the endogenous strong promoter Pthl. The heterologous NADP+-dependent 3-hydroxybutyryl-CoA dehydrogenase (Hbd1) from C. kluyveri was expressed in TM-07, and the yield of the recombinant protein reached 30.4-42.4% of the total cellular protein, surpassing the strong protein expression systems in other Gram-positive bacteria. The relative activity of Hbd1 in the crude enzyme was 198.0 U/mg, which was 8.3-fold higher than the natural activity in C. kluyveri. The relative activity of the purified enzyme reached 467.4 U/mg. To the best of our knowledge, this study represents the first application of the T7 expression system in Clostridium species, and this optimized expression system holds great potential for large-scale endotoxin-free recombinant protein production under strictly anaerobic conditions. This development paves the way for significant advancements in biotechnology and opens up new avenues for industrial applications.
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Affiliation(s)
- Yuechao Ma
- Department of Biosystems Engineering, Auburn University, Auburn, Alabama 36849, United States
- Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
| | - Na Guo
- Department of Biosystems Engineering, Auburn University, Auburn, Alabama 36849, United States
- Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
| | - Xiao Li
- Department of Crop, Soil and Environmental Sciences, Auburn University, Auburn, Alabama 36849, United States
| | - Zhihua Jiang
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Dunhua Zhang
- Aquatic Animal Health Research Unit, Agricultural Research Service, USDA, Auburn, Alabama 36832, United States
| | - Liang Guo
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Yi Wang
- Department of Biosystems Engineering, Auburn University, Auburn, Alabama 36849, United States
- Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
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Moreira JPC, Heap JT, Alves JI, Domingues L. Developing a genetic engineering method for Acetobacterium wieringae to expand one-carbon valorization pathways. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:24. [PMID: 36788587 PMCID: PMC9930230 DOI: 10.1186/s13068-023-02259-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 01/05/2023] [Indexed: 02/16/2023]
Abstract
BACKGROUND Developing new bioprocesses to produce chemicals and fuels with reduced production costs will greatly facilitate the replacement of fossil-based raw materials. In most fermentation bioprocesses, the feedstock usually represents the highest cost, which becomes the target for cost reduction. Additionally, the biorefinery concept advocates revenue growth from the production of several compounds using the same feedstock. Taken together, the production of bio commodities from low-cost gas streams containing CO, CO2, and H2, obtained from the gasification of any carbon-containing waste streams or off-gases from heavy industry (steel mills, processing plants, or refineries), embodies an opportunity for affordable and renewable chemical production. To achieve this, by studying non-model autotrophic acetogens, current limitations concerning low growth rates, toxicity by gas streams, and low productivity may be overcome. The Acetobacterium wieringae strain JM is a novel autotrophic acetogen that is capable of producing acetate and ethanol. It exhibits faster growth rates on various gaseous compounds, including carbon monoxide, compared to other Acetobacterium species, making it potentially useful for industrial applications. The species A. wieringae has not been genetically modified, therefore developing a genetic engineering method is important for expanding its product portfolio from gas fermentation and overall improving the characteristics of this acetogen for industrial demands. RESULTS This work reports the development and optimization of an electrotransformation protocol for A. wieringae strain JM, which can also be used in A. wieringae DSM 1911, and A. woodii DSM 1030. We also show the functionality of the thiamphenicol resistance marker, catP, and the functionality of the origins of replication pBP1, pCB102, pCD6, and pIM13 in all tested Acetobacterium strains, with transformation efficiencies of up to 2.0 × 103 CFU/μgDNA. Key factors affecting electrotransformation efficiency include OD600 of cell harvesting, pH of resuspension buffer, the field strength of the electric pulse, and plasmid amount. Using this method, the acetone production operon from Clostridium acetobutylicum was efficiently introduced in all tested Acetobacterium spp., leading to non-native biochemical acetone production via plasmid-based expression. CONCLUSIONS A. wieringae can be electrotransformed at high efficiency using different plasmids with different replication origins. The electrotransformation procedure and tools reported here unlock the genetic and metabolic manipulation of the biotechnologically relevant A. wieringae strains. For the first time, non-native acetone production is shown in A. wieringae.
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Affiliation(s)
- João P. C. Moreira
- grid.10328.380000 0001 2159 175XCEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal ,LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - John T. Heap
- grid.4563.40000 0004 1936 8868School of Life Sciences, University of Nottingham, Biodiscovery Institute, University Park, Nottingham, NG7 2RD UK
| | - Joana I. Alves
- grid.10328.380000 0001 2159 175XCEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal ,LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Lucília Domingues
- CEB - Centre of Biological Engineering, University of Minho, 4710-057, Braga, Portugal. .,LABBELS - Associate Laboratory, Braga/Guimarães, Portugal.
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Dykstra JC, van Oort J, Yazdi AT, Vossen E, Patinios C, van der Oost J, Sousa DZ, Kengen SWM. Metabolic engineering of Clostridium autoethanogenum for ethyl acetate production from CO. Microb Cell Fact 2022; 21:243. [DOI: 10.1186/s12934-022-01964-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 10/18/2022] [Indexed: 11/25/2022] Open
Abstract
Abstract
Background
Ethyl acetate is a bulk chemical traditionally produced via energy intensive chemical esterification. Microbial production of this compound offers promise as a more sustainable alternative process. So far, efforts have focused on using sugar-based feedstocks for microbial ester production, but extension to one-carbon substrates, such as CO and CO2/H2, is desirable. Acetogens present a promising microbial platform for the production of ethyl esters from these one-carbon substrates.
Results
We engineered the acetogen C. autoethanogenum to produce ethyl acetate from CO by heterologous expression of an alcohol acetyltransferase (AAT), which catalyzes the formation of ethyl acetate from acetyl-CoA and ethanol. Two AATs, Eat1 from Kluyveromyces marxianus and Atf1 from Saccharomyces cerevisiae, were expressed in C. autoethanogenum. Strains expressing Atf1 produced up to 0.2 mM ethyl acetate. Ethyl acetate production was barely detectable (< 0.01 mM) for strains expressing Eat1. Supplementation of ethanol was investigated as potential boost for ethyl acetate production but resulted only in a 1.5-fold increase (0.3 mM ethyl acetate). Besides ethyl acetate, C. autoethanogenum expressing Atf1 could produce 4.5 mM of butyl acetate when 20 mM butanol was supplemented to the growth medium.
Conclusions
This work offers for the first time a proof-of-principle that autotrophic short chain ester production from C1-carbon feedstocks is possible and offers leads on how this approach can be optimized in the future.
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Lauer I, Philipps G, Jennewein S. Metabolic engineering of Clostridium ljungdahlii for the production of hexanol and butanol from CO 2 and H 2. Microb Cell Fact 2022; 21:85. [PMID: 35568911 PMCID: PMC9107641 DOI: 10.1186/s12934-022-01802-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/11/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The replacement of fossil fuels and petrochemicals with sustainable alternatives is necessary to mitigate the effects of climate change and also to counteract diminishing fossil resources. Acetogenic microorganisms such as Clostridium spp. are promising sources of fuels and basic chemical precursors because they efficiently utilize CO and CO2 as carbon source. However the conversion into high titers of butanol and hexanol is challenging. RESULTS Using a metabolic engineering approach we transferred a 17.9-kb gene cluster via conjugation, containing 13 genes from C. kluyveri and C. acetobutylicum for butanol and hexanol biosynthesis, into C. ljungdahlii. Plasmid-based expression resulted in 1075 mg L-1 butanol and 133 mg L-1 hexanol from fructose in complex medium, and 174 mg L-1 butanol and 15 mg L-1 hexanol from gaseous substrate (20% CO2 and 80% H2) in minimal medium. Product formation was increased by the genomic integration of the heterologous gene cluster. We confirmed the expression of all 13 enzymes by targeted proteomics and identified potential rate-limiting steps. Then, we removed the first-round selection marker using CRISPR/Cas9 and integrated an additional 7.8 kb gene cluster comprising 6 genes from C. carboxidivorans. This led to a significant increase in the hexanol titer (251 mg L-1) at the expense of butanol (158 mg L-1), when grown on CO2 and H2 in serum bottles. Fermentation of this strain at 2-L scale produced 109 mg L-1 butanol and 393 mg L-1 hexanol. CONCLUSIONS We thus confirmed the function of the butanol/hexanol biosynthesis genes and achieved hexanol biosynthesis in the syngas-fermenting species C. ljungdahlii for the first time, reaching the levels produced naturally by C. carboxidivorans. The genomic integration strain produced hexanol without selection and is therefore suitable for continuous fermentation processes.
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Affiliation(s)
- Ira Lauer
- Department for Industrial Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074, Aachen, Germany
| | - Gabriele Philipps
- Department for Industrial Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074, Aachen, Germany
| | - Stefan Jennewein
- Department for Industrial Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074, Aachen, Germany.
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Lee H, Bae J, Jin S, Kang S, Cho BK. Engineering Acetogenic Bacteria for Efficient One-Carbon Utilization. Front Microbiol 2022; 13:865168. [PMID: 35615514 PMCID: PMC9124964 DOI: 10.3389/fmicb.2022.865168] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/19/2022] [Indexed: 12/03/2022] Open
Abstract
C1 gases, including carbon dioxide (CO2) and carbon monoxide (CO), are major contributors to climate crisis. Numerous studies have been conducted to fix and recycle C1 gases in order to solve this problem. Among them, the use of microorganisms as biocatalysts to convert C1 gases to value-added chemicals is a promising solution. Acetogenic bacteria (acetogens) have received attention as high-potential biocatalysts owing to their conserved Wood–Ljungdahl (WL) pathway, which fixes not only CO2 but also CO. Although some metabolites have been produced via C1 gas fermentation on an industrial scale, the conversion of C1 gases to produce various biochemicals by engineering acetogens has been limited. The energy limitation of acetogens is one of the challenges to overcome, as their metabolism operates at a thermodynamic limit, and the low solubility of gaseous substrates results in a limited supply of cellular energy. This review provides strategies for developing efficient platform strains for C1 gas conversion, focusing on engineering the WL pathway. Supplying liquid C1 substrates, which can be obtained from CO2, or electricity is introduced as a strategy to overcome the energy limitation. Future prospective approaches on engineering acetogens based on systems and synthetic biology approaches are also discussed.
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Affiliation(s)
- Hyeonsik Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Jiyun Bae
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Sangrak Jin
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Seulgi Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Byung-Kwan Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
- *Correspondence: Byung-Kwan Cho,
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Calvo DC, Luna HJ, Arango JA, Torres CI, Rittmann BE. Determining global trends in syngas fermentation research through a bibliometric analysis. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 307:114522. [PMID: 35066199 DOI: 10.1016/j.jenvman.2022.114522] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 01/10/2022] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
Syngas fermentation, in which microorganisms convert H2, CO, and CO2 to acids and alcohols, is a promising alternative for carbon cycling and valorization. The intellectual landscape of the topic was characterized through a bibliometric analysis using a search query (SQ) that included all relevant documents on syngas fermentation available through the Web of Science database up to December 31st, 2021. The SQ was validated with a preliminary analysis in bibliometrix and a review of titles and abstracts of all sources. Although syngas fermentation began in the early 1980s, it grew rapidly beginning in 2008, with 92.5% of total publications and 87.3% of total citations from 2008 to 2021. The field has been steadily moving from fundamentals towards applications, suggesting that the field is maturing scientifically. The greatest number of publications and citations are from the USA, and researchers in China, Germany, and Spain also are highly active. Although collaborations have increased in the past few years, author-cluster analysis shows specialized research domains with little collaboration between groups. Based on topic trends, the main challenges to be address are related to mass-transfer limitations, and researchers are starting to explore mixed cultures, genetic engineering, microbial chain elongation, and biorefineries.
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Affiliation(s)
- Diana C Calvo
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, PO Box 85287-3005, USA; Biodesign Center for Health Through Microbiomes, Arizona State University, Tempe, AZ, PO Box 85287-3005, USA.
| | - Hector J Luna
- Grupo GRESIA, Department of Environmental Engineering, Universidad Antonio Nariño, Bogotá, 110231, Colombia; Environmental and Chemical Technology Group, Department of Chemistry, Federal University of Ouro Preto, Campus University, Campus Universitario, Brazil
| | - Jineth A Arango
- Pontificia Universidad Católica de Valparaíso, Valparaíso, 2362803, Chile.
| | - Cesar I Torres
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, PO Box 85287-3005, USA.
| | - Bruce E Rittmann
- Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ, PO Box 85287-3005, USA.
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Abstract
The majority of the genes present in bacterial genomes remain poorly characterized, with up to one-third of those that are protein encoding having no definitive function. Transposon insertion sequencing represents a high-throughput technique that can help rectify this deficiency. The technology, however, can only be realistically applied to those species in which high rates of DNA transfer can be achieved. Here, we have developed a number of approaches that overcome this barrier in the autotrophic species Clostridium autoethanogenum by using a mariner-based transposon system. The inherent instability of such systems in the Escherichia coli conjugation donor due to transposition events was counteracted through the incorporation of a conditionally lethal codA marker on the plasmid backbone. Relatively low frequencies of transformation of the plasmid into C. autoethanogenum were circumvented through the use of a plasmid that is conditional for replication coupled with the routine implementation of an Illumina library preparation protocol that eliminates plasmid-based reads. A transposon library was then used to determine the essential genes needed for growth using carbon monoxide as the sole carbon and energy source. IMPORTANCE Although microbial genome sequences are relatively easily determined, assigning gene function remains a bottleneck. Consequently, relatively few genes are well characterized, leaving the function of many as either hypothetical or entirely unknown. High-throughput transposon sequencing can help remedy this deficiency, but is generally only applicable to microbes with efficient DNA transfer procedures. These exclude many microorganisms of importance to humankind either as agents of disease or as industrial process organisms. Here, we developed approaches to facilitate transposon insertion sequencing in the acetogen Clostridium autoethanogenum, a chassis being exploited to convert single-carbon waste gases CO and CO2 into chemicals and fuels at an industrial scale. This allowed the determination of gene essentiality under heterotrophic and autotrophic growth, providing insights into the utilization of CO as a sole carbon and energy source. The strategies implemented are translatable and will allow others to apply transposon insertion sequencing to other microbes where DNA transfer has until now represented a barrier to progress.
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11
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Carbon-negative production of acetone and isopropanol by gas fermentation at industrial pilot scale. Nat Biotechnol 2022; 40:335-344. [DOI: 10.1038/s41587-021-01195-w] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/09/2021] [Indexed: 12/21/2022]
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Autotrophic lactate production from H2 + CO2 using recombinant and fluorescent FAST-tagged Acetobacterium woodii strains. Appl Microbiol Biotechnol 2022; 106:1447-1458. [PMID: 35092454 PMCID: PMC8882112 DOI: 10.1007/s00253-022-11770-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/23/2021] [Accepted: 01/07/2022] [Indexed: 12/12/2022]
Abstract
AbstractLactate has various uses as industrial platform chemical, poly-lactic acid precursor or feedstock for anaerobic co-cultivations. The aim of this study was to construct and characterise Acetobacterium woodii strains capable of autotrophic lactate production. Therefore, the lctBCD genes, encoding the native Lct dehydrogenase complex, responsible for lactate consumption, were knocked out. Subsequently, a gene encoding a d-lactate dehydrogenase (LDHD) originating from Leuconostoc mesenteroides was expressed in A. woodii, either under the control of the anhydrotetracycline-inducible promoter Ptet or under the lactose-inducible promoter PbgaL. Moreover, LDHD was N-terminally fused to the oxygen-independent fluorescence-activating and absorption-shifting tag (FAST) and expressed in respective A. woodii strains. Cells that produced the LDHD fusion protein were capable of lactate production of up to 18.8 mM in autotrophic batch experiments using H2 + CO2 as energy and carbon source. Furthermore, cells showed a clear and bright fluorescence during exponential growth, as well as in the stationary phase after induction, mediated by the N-terminal FAST. Flow cytometry at the single-cell level revealed phenotypic heterogeneities for cells expressing the FAST-tagged LDHD fusion protein. This study shows that FAST provides a new reporter tool to quickly analyze gene expression over the course of growth experiments of A. woodii. Consequently, fluorescence-based reporters allow for faster and more targeted optimization of production strains.Key points
•Autotrophic lactate production was achieved with A. woodii.
•FAST functions as fluorescent marker protein in A. woodii.
•Fluorescence measurements on single-cell level revealed population heterogeneity.
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13
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Arslan K, Schoch T, Höfele F, Herrschaft S, Oberlies C, Bengelsdorf F, Veiga MC, Dürre P, Kennes C. Engineering
Acetobacterium woodii
for the production of isopropanol and acetone from carbon dioxide and hydrogen. Biotechnol J 2022; 17:e2100515. [DOI: 10.1002/biot.202100515] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Kübra Arslan
- Chemical Enginering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), BIOENGIN group University of La Coruña Rúa da Fraga 10 La Coruña 15008 Spain
| | - Teresa Schoch
- Institute of Microbiology and Biotechnology University of Ulm Albert‐Einstein‐Allee 11 Ulm 89081 Germany
| | - Franziska Höfele
- Institute of Microbiology and Biotechnology University of Ulm Albert‐Einstein‐Allee 11 Ulm 89081 Germany
| | - Sabrina Herrschaft
- Institute of Microbiology and Biotechnology University of Ulm Albert‐Einstein‐Allee 11 Ulm 89081 Germany
| | - Catarina Oberlies
- Institute of Microbiology and Biotechnology University of Ulm Albert‐Einstein‐Allee 11 Ulm 89081 Germany
| | - Frank Bengelsdorf
- Institute of Microbiology and Biotechnology University of Ulm Albert‐Einstein‐Allee 11 Ulm 89081 Germany
| | - María C. Veiga
- Chemical Enginering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), BIOENGIN group University of La Coruña Rúa da Fraga 10 La Coruña 15008 Spain
| | - Peter Dürre
- Institute of Microbiology and Biotechnology University of Ulm Albert‐Einstein‐Allee 11 Ulm 89081 Germany
| | - Christian Kennes
- Chemical Enginering Laboratory, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), BIOENGIN group University of La Coruña Rúa da Fraga 10 La Coruña 15008 Spain
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14
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Pavan M, Reinmets K, Garg S, Mueller AP, Marcellin E, Köpke M, Valgepea K. Advances in systems metabolic engineering of autotrophic carbon oxide-fixing biocatalysts towards a circular economy. Metab Eng 2022; 71:117-141. [DOI: 10.1016/j.ymben.2022.01.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 12/16/2022]
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15
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Lee J. Lessons from Clostridial Genetics: Toward Engineering Acetogenic Bacteria. BIOTECHNOL BIOPROC E 2021. [DOI: 10.1007/s12257-021-0062-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Sanford PA, Woolston BM. Synthetic or natural? Metabolic engineering for assimilation and valorization of methanol. Curr Opin Biotechnol 2021; 74:171-179. [PMID: 34952430 DOI: 10.1016/j.copbio.2021.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 11/23/2021] [Accepted: 12/01/2021] [Indexed: 01/01/2023]
Abstract
Single carbon (C1) substrates such as methanol are gaining increasing attention as cost-effective and environmentally friendly microbial feedstocks. Recent impressive metabolic engineering efforts to import C1 catabolic pathways into the non-methylotrophic bacterium Escherichia coli have led to synthetic strains growing on methanol as the sole carbon source. However, the growth rate and product yield in these strains remain inferior to native methylotrophs. Meanwhile, an ever-expanding genetic engineering toolbox is increasing the tractability of native C1 utilizers, raising the question of whether it is best to use an engineered strain or a native host for the microbial assimilation of C1 substrates. Here we provide perspective on this debate, using recent work in E. coli and the methylotrophic acetogen Eubacterium limosum as case studies.
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Affiliation(s)
- Patrick A Sanford
- Northeastern University, Department of Chemical Engineering, 360 Huntington Avenue, 223 Cullinane, United States
| | - Benjamin M Woolston
- Northeastern University, Department of Chemical Engineering, 360 Huntington Avenue, 223 Cullinane, United States.
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17
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Valorisation of CO2 into Value-Added Products via Microbial Electrosynthesis (MES) and Electro-Fermentation Technology. FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7040291] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microbial electrocatalysis reckons on microbes as catalysts for reactions occurring at electrodes. Microbial fuel cells and microbial electrolysis cells are well-known in this context; both prefer the oxidation of organic and inorganic matter for producing electricity. Notably, the synthesis of high energy-density chemicals (fuels) or their precursors by microorganisms using bio-cathode to yield electrical energy is called Microbial Electrosynthesis (MES), giving an exceptionally appealing novel way for producing beneficial products from electricity and wastewater. This review accentuates the concept, importance and opportunities of MES, as an emerging discipline at the nexus of microbiology and electrochemistry. Production of organic compounds from MES is considered as an effective technique for the generation of various beneficial reduced end-products (like acetate and butyrate) as well as in reducing the load of CO2 from the atmosphere to mitigate the harmful effect of greenhouse gases in global warming. Although MES is still an emerging technology, this method is not thoroughly known. The authors have focused on MES, as it is the next transformative, viable alternative technology to decrease the repercussions of surplus carbon dioxide in the environment along with conserving energy.
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18
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Jia D, He M, Tian Y, Shen S, Zhu X, Wang Y, Zhuang Y, Jiang W, Gu Y. Metabolic Engineering of Gas-Fermenting Clostridium ljungdahlii for Efficient Co-production of Isopropanol, 3-Hydroxybutyrate, and Ethanol. ACS Synth Biol 2021; 10:2628-2638. [PMID: 34549587 DOI: 10.1021/acssynbio.1c00235] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rational design and modification of autotrophic bacteria to efficiently produce high-value chemicals and biofuels are crucial for establishing a sustainable and economically viable process for one-carbon (C1) source utilization, which, however, remains a challenge in metabolic engineering. In this study, autotrophic Clostridium ljungdahlii was metabolically engineered to efficiently co-produce three important bulk chemicals, isopropanol, 3-hydroxybutyrate (3-HB), and ethanol (together, IHE), using syngas (CO2/CO). An artificial isopropanol-producing pathway was first constructed and optimized in C. ljungdahlii to achieve an efficient production of isopropanol and an unexpected product, 3-HB. Based on this finding, an endogenous active dehydrogenase capable of converting acetoacetate to 3-HB was identified in C. ljungdahlii, thereby revealing an efficient 3-HB-producing pathway. The engineered strain was further optimized to reassimilate acetic acid and synthesize 3-HB by introducing heterologous functional genes. Finally, the best-performing strain was able to produce 13.4, 3.0, and 28.4 g/L of isopropanol, 3-HB, and ethanol, respectively, in continuous gas fermentation. Therefore, this work represents remarkable progress in microbial production of bulk chemicals using C1 gases.
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Affiliation(s)
- Dechen Jia
- Key Laboratory of Synthetic Biology, The State Key Laboratory of Plant Carbon-Nitrogen Assimilation, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Meiyu He
- Key Laboratory of Synthetic Biology, The State Key Laboratory of Plant Carbon-Nitrogen Assimilation, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Yi Tian
- Key Laboratory of Synthetic Biology, The State Key Laboratory of Plant Carbon-Nitrogen Assimilation, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Shaohuang Shen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xianfeng Zhu
- Key Laboratory of Plant Stress Biology, State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Yonghong Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yingping Zhuang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Weihong Jiang
- Key Laboratory of Synthetic Biology, The State Key Laboratory of Plant Carbon-Nitrogen Assimilation, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yang Gu
- Key Laboratory of Synthetic Biology, The State Key Laboratory of Plant Carbon-Nitrogen Assimilation, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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19
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Joseph RC, Kelley SQ, Kim NM, Sandoval NR. Metabolic Engineering and the Synthetic Biology Toolbox for
Clostridium. Metab Eng 2021. [DOI: 10.1002/9783527823468.ch16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Debabov VG. Acetogens: Biochemistry, Bioenergetics, Genetics, and Biotechnological Potential. Microbiology (Reading) 2021. [DOI: 10.1134/s0026261721030024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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21
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Flaiz M, Ludwig G, Bengelsdorf FR, Dürre P. Production of the biocommodities butanol and acetone from methanol with fluorescent FAST-tagged proteins using metabolically engineered strains of Eubacterium limosum. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:117. [PMID: 33971948 PMCID: PMC8111989 DOI: 10.1186/s13068-021-01966-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 04/29/2021] [Indexed: 05/12/2023]
Abstract
BACKGROUND The interest in using methanol as a substrate to cultivate acetogens increased in recent years since it can be sustainably produced from syngas and has the additional benefit of reducing greenhouse gas emissions. Eubacterium limosum is one of the few acetogens that can utilize methanol, is genetically accessible and, therefore, a promising candidate for the recombinant production of biocommodities from this C1 carbon source. Although several genetic tools are already available for certain acetogens including E. limosum, the use of brightly fluorescent reporter proteins is still limited. RESULTS In this study, we expanded the genetic toolbox of E. limosum by implementing the fluorescence-activating and absorption shifting tag (FAST) as a fluorescent reporter protein. Recombinant E. limosum strains that expressed the gene encoding FAST in an inducible and constitutive manner were constructed. Cultivation of these recombinant strains resulted in brightly fluorescent cells even under anaerobic conditions. Moreover, we produced the biocommodities butanol and acetone from methanol with recombinant E. limosum strains. Therefore, we used E. limosum cultures that produced FAST-tagged fusion proteins of the bifunctional acetaldehyde/alcohol dehydrogenase or the acetoacetate decarboxylase, respectively, and determined the fluorescence intensity and product concentrations during growth. CONCLUSIONS The addition of FAST as an oxygen-independent fluorescent reporter protein expands the genetic toolbox of E. limosum. Moreover, our results show that FAST-tagged fusion proteins can be constructed without negatively impacting the stability, functionality, and productivity of the resulting enzyme. Finally, butanol and acetone can be produced from methanol using recombinant E. limosum strains expressing genes encoding fluorescent FAST-tagged fusion proteins.
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Affiliation(s)
- Maximilian Flaiz
- Institute of Microbiology and Biotechnology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Gideon Ludwig
- Institute of Microbiology and Biotechnology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Frank R Bengelsdorf
- Institute of Microbiology and Biotechnology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
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22
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Kato J, Takemura K, Kato S, Fujii T, Wada K, Iwasaki Y, Aoi Y, Matsushika A, Murakami K, Nakashimada Y. Metabolic engineering of Moorella thermoacetica for thermophilic bioconversion of gaseous substrates to a volatile chemical. AMB Express 2021; 11:59. [PMID: 33891189 PMCID: PMC8065083 DOI: 10.1186/s13568-021-01220-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 04/09/2021] [Indexed: 11/26/2022] Open
Abstract
Gas fermentation is one of the promising bioprocesses to convert CO2 or syngas to important chemicals. Thermophilic gas fermentation of volatile chemicals has the potential for the development of consolidated bioprocesses that can simultaneously separate products during fermentation. This study reports the production of acetone from CO2 and H2, CO, or syngas by introducing the acetone production pathway using acetyl–coenzyme A (Ac-CoA) and acetate produced via the Wood–Ljungdahl pathway in Moorella thermoacetica. Reducing the carbon flux from Ac-CoA to acetate through genetic engineering successfully enhanced acetone productivity, which varied on the basis of the gas composition. The highest acetone productivity was obtained with CO–H2, while autotrophic growth collapsed with CO2–H2. By adding H2 to CO, the acetone productivity from the same amount of carbon source increased compared to CO gas only, and the maximum specific acetone production rate also increased from 0.04 to 0.09 g-acetone/g-dry cell/h. Our development of the engineered thermophilic acetogen M. thermoacetica, which grows at a temperature higher than the boiling point of acetone (58 °C), would pave the way for developing a consolidated process with simplified and cost-effective recovery via condensation following gas fermentation.
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23
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Bourgade B, Minton NP, Islam MA. Genetic and metabolic engineering challenges of C1-gas fermenting acetogenic chassis organisms. FEMS Microbiol Rev 2021; 45:fuab008. [PMID: 33595667 PMCID: PMC8351756 DOI: 10.1093/femsre/fuab008] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 01/15/2021] [Indexed: 12/11/2022] Open
Abstract
Unabated mining and utilisation of petroleum and petroleum resources and their conversion to essential fuels and chemicals have drastic environmental consequences, contributing to global warming and climate change. In addition, fossil fuels are finite resources, with a fast-approaching shortage. Accordingly, research efforts are increasingly focusing on developing sustainable alternatives for chemicals and fuels production. In this context, bioprocesses, relying on microorganisms, have gained particular interest. For example, acetogens use the Wood-Ljungdahl pathway to grow on single carbon C1-gases (CO2 and CO) as their sole carbon source and produce valuable products such as acetate or ethanol. These autotrophs can, therefore, be exploited for large-scale fermentation processes to produce industrially relevant chemicals from abundant greenhouse gases. In addition, genetic tools have recently been developed to improve these chassis organisms through synthetic biology approaches. This review will focus on the challenges of genetically and metabolically modifying acetogens. It will first discuss the physical and biochemical obstacles complicating successful DNA transfer in these organisms. Current genetic tools developed for several acetogens, crucial for strain engineering to consolidate and expand their catalogue of products, will then be described. Recent tool applications for metabolic engineering purposes to allow redirection of metabolic fluxes or production of non-native compounds will lastly be covered.
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Affiliation(s)
- Barbara Bourgade
- Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, University Park, University of Nottingham, Nottingham, Nottinghamshire, NG7 2RD, UK
| | - M Ahsanul Islam
- Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK
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24
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Abstract
Goal of sustainable carbon neutral economy can be achieved by designing an efficient CO2 reduction system to generate biofuels, in particular, by mimicking the mechanism of natural photosynthesis using semiconducting nanomaterials interfaced with electroactive bacteria (EAB) in a photosynthetic microbial electrosynthesis (PMES) system. This review paper presents an overview of the recent advancements in the biohybrid photoanode and photocathode materials. We discuss the reaction mechanism observed at photoanode and photocathode to enhance our understanding on the solar driven MES. We extend the discussion by showcasing the potential activity of EABs toward high selectivity and production rates for desirable products by manipulating their genomic sequence. Additionally, the critical challenges associated in scaling up the PMES system including the strategies for diminution of reactive oxygen species, low solubility of CO2 in the typical electrolytes, low selectivity of product species are presented along with the suggestions of alternative strategies to achieve economically viable generation of (bio)commodities.
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25
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Schwarz FM, Ciurus S, Jain S, Baum C, Wiechmann A, Basen M, Müller V. Revealing formate production from carbon monoxide in wild type and mutants of Rnf- and Ech-containing acetogens, Acetobacterium woodii and Thermoanaerobacter kivui. Microb Biotechnol 2020; 13:2044-2056. [PMID: 32959527 PMCID: PMC7533326 DOI: 10.1111/1751-7915.13663] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 01/18/2023] Open
Abstract
Acetogenic bacteria have gained much attraction in recent years as they can produce different biofuels and biochemicals from H2 plus CO2 or even CO alone, therefore opening a promising alternative route for the production of biofuels from renewable sources compared to existing sugar-based routes. However, CO metabolism still raises questions concerning the biochemistry and bioenergetics in many acetogens. In this study, we focused on the two acetogenic bacteria Acetobacterium woodii and Thermoanaerobacter kivui which, so far, are the only identified acetogens harbouring a H2 -dependent CO2 reductase and furthermore belong to different classes of 'Rnf'- and 'Ech-acetogens'. Both strains catalysed the conversion of CO into the bulk chemical acetate and formate. Formate production was stimulated by uncoupling the energy metabolism from the Wood-Ljungdahl pathway, and specific rates of 1.44 and 1.34 mmol g-1 h-1 for A. woodii ∆rnf and T. kivui wild type were reached. The demonstrated CO-based formate production rates are, to the best of our knowledge, among the highest rates ever reported. Using mutants of ∆hdcr, ∆cooS, ∆hydBA, ∆rnf and ∆ech2 with deficiencies in key enzyme activities of the central metabolism enabled us to postulate two different CO utilization pathways in these two model organisms.
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Affiliation(s)
- Fabian M. Schwarz
- Molecular Microbiology and BioenergeticsInstitute of Molecular BiosciencesJohann Wolfgang Goethe UniversityFrankfurt am MainGermany
| | - Sarah Ciurus
- Molecular Microbiology and BioenergeticsInstitute of Molecular BiosciencesJohann Wolfgang Goethe UniversityFrankfurt am MainGermany
| | - Surbhi Jain
- Molecular Microbiology and BioenergeticsInstitute of Molecular BiosciencesJohann Wolfgang Goethe UniversityFrankfurt am MainGermany
| | - Christoph Baum
- MicrobiologyInstitute of Biological SciencesUniversity RostockRostockGermany
| | - Anja Wiechmann
- Molecular Microbiology and BioenergeticsInstitute of Molecular BiosciencesJohann Wolfgang Goethe UniversityFrankfurt am MainGermany
| | - Mirko Basen
- MicrobiologyInstitute of Biological SciencesUniversity RostockRostockGermany
| | - Volker Müller
- Molecular Microbiology and BioenergeticsInstitute of Molecular BiosciencesJohann Wolfgang Goethe UniversityFrankfurt am MainGermany
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26
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Synthetic Biology on Acetogenic Bacteria for Highly Efficient Conversion of C1 Gases to Biochemicals. Int J Mol Sci 2020; 21:ijms21207639. [PMID: 33076477 PMCID: PMC7589590 DOI: 10.3390/ijms21207639] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/13/2020] [Accepted: 10/13/2020] [Indexed: 12/13/2022] Open
Abstract
Synthesis gas, which is mainly produced from fossil fuels or biomass gasification, consists of C1 gases such as carbon monoxide, carbon dioxide, and methane as well as hydrogen. Acetogenic bacteria (acetogens) have emerged as an alternative solution to recycle C1 gases by converting them into value-added biochemicals using the Wood-Ljungdahl pathway. Despite the advantage of utilizing acetogens as biocatalysts, it is difficult to develop industrial-scale bioprocesses because of their slow growth rates and low productivities. To solve these problems, conventional approaches to metabolic engineering have been applied; however, there are several limitations owing to the lack of required genetic bioparts for regulating their metabolic pathways. Recently, synthetic biology based on genetic parts, modules, and circuit design has been actively exploited to overcome the limitations in acetogen engineering. This review covers synthetic biology applications to design and build industrial platform acetogens.
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27
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Xia PF, Casini I, Schulz S, Klask CM, Angenent LT, Molitor B. Reprogramming Acetogenic Bacteria with CRISPR-Targeted Base Editing via Deamination. ACS Synth Biol 2020; 9:2162-2171. [PMID: 32610012 DOI: 10.1021/acssynbio.0c00226] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Acetogenic bacteria are rising in popularity as chassis microbes for biotechnology due to their capability of converting inorganic one-carbon (C1) gases to organic chemicals. To fully uncover the potential of acetogenic bacteria, synthetic biology tools are imperative to either engineer designed functions or to interrogate the physiology. Here, we report a genome-editing tool at a one-nucleotide resolution, namely base editing, for acetogenic bacteria based on CRISPR-targeted deamination. This tool combines nuclease deactivated Cas9 with activation-induced cytidine deaminase to enable cytosine-to-thymine substitution without DNA cleavage, homology-directed repair, and donor DNA, which are generally the bottlenecks for applying conventional CRISPR-Cas systems in bacteria. We designed and validated a modularized base-editing tool in the model acetogenic bacterium Clostridium ljungdahlii. The editing principles were investigated, and an in-silico analysis revealed the capability of base editing across the genome and the potential for off-target events. Moreover, genes related to acetate and ethanol production were disrupted individually by installing premature STOP codons to reprogram carbon flux toward improved acetate production. This resulted in engineered C. ljungdahlii strains with the desired phenotypes and stable genotypes. Our base-editing tool promotes the application and research in acetogenic bacteria and provides a blueprint to upgrade CRISPR-Cas-based genome editing in bacteria in general.
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Affiliation(s)
- Peng-Fei Xia
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Isabella Casini
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Sarah Schulz
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Christian-Marco Klask
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
| | - Largus T. Angenent
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
- AG Angenent, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Bastian Molitor
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, 72074 Tübingen, Germany
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28
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Han S, Kim Y, Karanjikar M, San KY, Bennett GN. Genetic sensor-regulators functional in Clostridia. J Ind Microbiol Biotechnol 2020; 47:609-620. [DOI: 10.1007/s10295-020-02303-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/18/2020] [Indexed: 11/30/2022]
Abstract
Abstract
This study addressed the functionality of genetic circuits carrying natural regulatory elements of Clostridium acetobutylicum ATCC 824 in the presence of the respective inducer molecules. Specifically, promoters and their regulators involved in diverse carbon source utilization were characterized using mCherryOpt or beta-galactosidase as a reporter. Consequently, most of the genetic circuits tested in this study were functional in Clostridium acetobutylicum ATCC 824 in the presence of an inducer, leading to the expression of reporter proteins. These genetic sensor-regulators were found to be transferable to another Clostridium species, such as Clostridium beijerinckii NCIMB 8052. The gradual expression of reporter protein was observed as a function of the carbohydrates of interest. A xylose-inducible promoter allows a titratable and robust expression of a reporter protein with stringency and efficacy. This xylose-inducible circuit was seen to enable induction of the expression of reporter proteins in the presence of actual sugar mixtures incorporated in woody hydrolysate wherein glucose and xylose are present as predominant carbon sources.
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Affiliation(s)
- SongI Han
- grid.21940.3e 0000 0004 1936 8278 Department of Bioengineering Rice University 77005 Houston TX USA
| | - Younghwan Kim
- grid.427405.0 Technology Holding LLC 84119 West Valley City UT USA
| | | | - Ka-Yiu San
- grid.21940.3e 0000 0004 1936 8278 Department of Bioengineering Rice University 77005 Houston TX USA
- grid.21940.3e 0000 0004 1936 8278 Department of Chemical and Biomolecular Engineering Rice University 77005 Houston TX USA
| | - George N Bennett
- grid.21940.3e 0000 0004 1936 8278 Department of Chemical and Biomolecular Engineering Rice University 77005 Houston TX USA
- grid.21940.3e 0000 0004 1936 8278 Department of BioSciences Rice University 77005 Houston TX USA
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29
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Zhang L, Zhao R, Jia D, Jiang W, Gu Y. Engineering Clostridium ljungdahlii as the gas-fermenting cell factory for the production of biofuels and biochemicals. Curr Opin Chem Biol 2020; 59:54-61. [PMID: 32480247 DOI: 10.1016/j.cbpa.2020.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/08/2020] [Accepted: 04/12/2020] [Indexed: 01/08/2023]
Abstract
Clostridium ljungdahlii is a representative autotrophic gas-fermenting acetogen capable of converting CO2 and CO into biomass and multiple metabolites. The carbon fixation and conversion based on C. ljungdahlii have great potential for the sustainable production of bulk biochemicals and biofuels using industrial syngas and waste gases. With substantial recent advances in genetic manipulation tools, it has become possible to study and improve the metabolic capability of C. ljungdahlii in gas fermentation. The product scope of C. ljungdahlii has been expanded through the introduction of heterologous production pathways followed by the modification of native metabolic networks. In addition, progress has been made in understanding the physiological and metabolic mechanisms of this anaerobe, contributing to strain designs for expected phenotypes. In this review, we highlight the latest research progresses regarding C. ljungdahlii and discuss the next steps to comprehensively understand and engineer this bacterium for an improved bacterial gas bioconversion platform.
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Affiliation(s)
- Lu Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ran Zhao
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China; University of Chinese Academy of Sciences, Beijing, China
| | - Dechen Jia
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China; University of Chinese Academy of Sciences, Beijing, China
| | - Weihong Jiang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.
| | - Yang Gu
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.
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Beck MH, Flaiz M, Bengelsdorf FR, Dürre P. Induced heterologous expression of the arginine deiminase pathway promotes growth advantages in the strict anaerobe Acetobacterium woodii. Appl Microbiol Biotechnol 2019; 104:687-699. [DOI: 10.1007/s00253-019-10248-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/30/2019] [Accepted: 11/05/2019] [Indexed: 01/12/2023]
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31
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Müller V. New Horizons in Acetogenic Conversion of One-Carbon Substrates and Biological Hydrogen Storage. Trends Biotechnol 2019; 37:1344-1354. [DOI: 10.1016/j.tibtech.2019.05.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 05/17/2019] [Accepted: 05/23/2019] [Indexed: 01/12/2023]
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Strategies for improving the electroactivity and specific metabolic functionality of microorganisms for various microbial electrochemical technologies. Biotechnol Adv 2019; 39:107468. [PMID: 31707076 DOI: 10.1016/j.biotechadv.2019.107468] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 11/02/2019] [Accepted: 11/04/2019] [Indexed: 01/31/2023]
Abstract
Electroactive microorganisms, which possess extracellular electron transfer (EET) capabilities, are the basis of microbial electrochemical technologies (METs) such as microbial fuel and electrolysis cells. These are considered for several applications ranging from the energy-efficient treatment of waste streams to the production of value-added chemicals and fuels, bioremediation, and biosensing. Various aspects related to the microorganisms, electrodes, separators, reactor design, and operational or process parameters influence the overall functioning of METs. The most fundamental and critical performance-determining factor is, however, the microorganism-electrode interactions. Modification of the electrode surfaces and microorganisms for optimizing their interactions has therefore been the major MET research focus area over the last decade. In the case of microorganisms, primarily their EET mechanisms and efficiencies along with the biofilm formation capabilities, collectively considered as microbial electroactivity, affect their interactions with the electrodes. In addition to electroactivity, the specific metabolic or biochemical functionality of microorganisms is equally crucial to the target MET application. In this article, we present the major strategies that are used to enhance the electroactivity and specific functionality of microorganisms pertaining to both anodic and cathodic processes of METs. These include simple physical methods based on the use of heat and magnetic field along with chemical, electrochemical, and growth media amendment approaches to the complex procedure-based microbial bioaugmentation, co-culture, and cell immobilization or entrapment, and advanced toolkit-based biofilm engineering, genetic modifications, and synthetic biology strategies. We further discuss the applicability and limitations of these strategies and possible future research directions for advancing the highly promising microbial electrochemistry-driven biotechnology.
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Zhang S, Xu Z, Qin L, Kong J. Development of strong lactose/galactose-inducible expression system for Lactobacillus plantarum by optimizing promoter. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.107316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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34
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Woods C, Humphreys CM, Rodrigues RM, Ingle P, Rowe P, Henstra AM, Köpke M, Simpson SD, Winzer K, Minton NP. A novel conjugal donor strain for improved DNA transfer into Clostridium spp. Anaerobe 2019; 59:184-191. [PMID: 31269456 PMCID: PMC6866869 DOI: 10.1016/j.anaerobe.2019.06.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 06/27/2019] [Accepted: 06/29/2019] [Indexed: 12/29/2022]
Abstract
Clostridium encompasses species which are relevant to human and animal disease as well as species which have industrial potential, for instance, as producers of chemicals and fuels or as tumour delivery vehicles. Genetic manipulation of these target organisms is critical for advances in these fields. DNA transfer efficiencies, however, vary between species. Low efficiencies can impede the progress of research efforts. A novel conjugal donor strain of Escherichia coli has been created which exhibits a greater than 10-fold increases in conjugation efficiency compared to the traditionally used CA434 strain in the three species tested; C. autoethanogenum DSM 10061, C. sporogenes NCIMB 10696 and C. difficile R20291. The novel strain, designated 'sExpress', does not methylate DNA at Dcm sites (CCWGG) which allows circumvention of cytosine-specific Type IV restriction systems. A robust protocol for conjugation is presented which routinely produces in the order of 105 transconjugants per millilitre of donor cells for C. autoethanogenum, 106 for C. sporogenes and 102 for C. difficile R20291. The novel strain created is predicted to be a superior conjugal donor in a wide range of species which possess Type IV restriction systems.
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Affiliation(s)
- Craig Woods
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Christopher M Humphreys
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Raquel Mesquita Rodrigues
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Patrick Ingle
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Peter Rowe
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Anne M Henstra
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Michael Köpke
- LanzaTech Inc., 8045 Lamon Avenue, Suite 400, Skokie, IL, USA
| | - Sean D Simpson
- LanzaTech Inc., 8045 Lamon Avenue, Suite 400, Skokie, IL, USA
| | - Klaus Winzer
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Nigel P Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The University of Nottingham, Nottingham, NG7 2RD, UK; NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham NG7 2RD, UK.
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Engineering Clostridium for improved solvent production: recent progress and perspective. Appl Microbiol Biotechnol 2019; 103:5549-5566. [DOI: 10.1007/s00253-019-09916-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 01/07/2023]
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Kuehne SA, Rood JI, Lyras D. Clostridial Genetics: Genetic Manipulation of the Pathogenic Clostridia. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0040-2018. [PMID: 31172914 PMCID: PMC11315012 DOI: 10.1128/microbiolspec.gpp3-0040-2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Indexed: 02/07/2023] Open
Abstract
The past 10 years have been revolutionary for clostridial genetics. The rise of next-generation sequencing led to the availability of annotated whole-genome sequences of the important pathogenic clostridia: Clostridium perfringens, Clostridioides (Clostridium) difficile, and Clostridium botulinum, but also Paeniclostridium (Clostridium) sordellii and Clostridium tetani. These sequences were a prerequisite for the development of functional, sophisticated genetic tools for the pathogenic clostridia. A breakthrough came in the early 2000s with the development of TargeTron-based technologies specific for the clostridia, such as ClosTron, an insertional gene inactivation tool. The following years saw a plethora of new technologies being developed, mostly for C. difficile, but also for other members of the genus, including C. perfringens. A range of tools is now available, allowing researchers to precisely delete genes, change single nucleotides in the genome, complement deletions, integrate novel DNA into genomes, or overexpress genes. There are tools for forward genetics, including an inducible transposon mutagenesis system for C. difficile. As the latest addition to the tool kit, clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 technologies have also been adopted for the construction of single and multiple gene deletions in C. difficile. This article summarizes the key genetic technologies available to manipulate, study, and understand the pathogenic clostridia.
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Affiliation(s)
- S A Kuehne
- School of Dentistry and Institute for Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - J I Rood
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia 3800
| | - D Lyras
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia 3800
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Huang H, Chai C, Yang S, Jiang W, Gu Y. Phage serine integrase-mediated genome engineering for efficient expression of chemical biosynthetic pathway in gas-fermenting Clostridium ljungdahlii. Metab Eng 2019; 52:293-302. [DOI: 10.1016/j.ymben.2019.01.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/19/2018] [Accepted: 01/07/2019] [Indexed: 10/27/2022]
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Philipps G, de Vries S, Jennewein S. Development of a metabolic pathway transfer and genomic integration system for the syngas-fermenting bacterium Clostridium ljungdahlii. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:112. [PMID: 31086564 PMCID: PMC6507227 DOI: 10.1186/s13068-019-1448-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 04/22/2019] [Indexed: 05/15/2023]
Abstract
BACKGROUND Clostridium spp. can synthesize valuable chemicals and fuels by utilizing diverse waste-stream substrates, including starchy biomass, lignocellulose, and industrial waste gases. However, metabolic engineering in Clostridium spp. is challenging due to the low efficiency of gene transfer and genomic integration of entire biosynthetic pathways. RESULTS We have developed a reliable gene transfer and genomic integration system for the syngas-fermenting bacterium Clostridium ljungdahlii based on the conjugal transfer of donor plasmids containing large transgene cassettes (> 5 kb) followed by the inducible activation of Himar1 transposase to promote integration. We established a conjugation protocol for the efficient generation of transconjugants using the Gram-positive origins of replication repL and repH. We also investigated the impact of DNA methylation on conjugation efficiency by testing donor constructs with all possible combinations of Dam and Dcm methylation patterns, and used bisulfite conversion and PacBio sequencing to determine the DNA methylation profile of the C. ljungdahlii genome, resulting in the detection of four sequence motifs with N6-methyladenosine. As proof of concept, we demonstrated the transfer and genomic integration of a heterologous acetone biosynthesis pathway using a Himar1 transposase system regulated by a xylose-inducible promoter. The functionality of the integrated pathway was confirmed by detecting enzyme proteotypic peptides and the formation of acetone and isopropanol by C. ljungdahlii cultures utilizing syngas as a carbon and energy source. CONCLUSIONS The developed multi-gene delivery system offers a versatile tool to integrate and stably express large biosynthetic pathways in the industrial promising syngas-fermenting microorganism C. ljungdahlii. The simple transfer and stable integration of large gene clusters (like entire biosynthetic pathways) is expanding the range of possible fermentation products of heterologously expressing recombinant strains. We also believe that the developed gene delivery system can be adapted to other clostridial strains as well.
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Affiliation(s)
- Gabriele Philipps
- Department for Industrial Biotechnology, Fraunhofer IME, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074 Aachen, Germany
| | - Sebastian de Vries
- Department for Industrial Biotechnology, Fraunhofer IME, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074 Aachen, Germany
- Present Address: Department of Intensive Care Medicine, University Hospital, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Stefan Jennewein
- Department for Industrial Biotechnology, Fraunhofer IME, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstr. 6, 52074 Aachen, Germany
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Li Y, Jin K, Zhang L, Ding Z, Gu Z, Shi G. Development of an Inducible Secretory Expression System in Bacillus licheniformis Based on an Engineered Xylose Operon. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:9456-9464. [PMID: 30129762 DOI: 10.1021/acs.jafc.8b02857] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The xylose operon can be an efficient biological component for regulatory expression uses in Bacillus licheniformis. However, its characteristic susceptibility to carbon catabolite repression (CCR) makes its application inconvenient. In this study, plasmids harboring the wild-type operons from three Bacillus species were constructed and introduced into B. licheniformis. These plasmids ensured secretory expression of maltogenic α-amylase (BLMA) in B. licheniformis under strict regulation. The glucose-mediated CCR was then alleviated by engineering the xylose operon of the expression system. Evidence showed that mutations in the highly conserved nucleotides of the identified catabolite responsive element (cre) consensus sequence prevented association of the regulator CcpA with DNA, thus resulting in an increase in BLMA activity of up to 12-fold. Furthermore, features of this engineered system for inducible expression were investigated. Induction in mid-log phase using 10 g/L xylose at 37 °C was found to be beneficial for promoting the accumulation of recombinant product, and the maximum yield of BlmMA reached 715.4 U/mL. This study contributes to the industrial application of the generally recognized as safe (GRAS) workhorse B. licheniformis.
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Affiliation(s)
- Youran Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Ke Jin
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Liang Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Zhongyang Ding
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Zhenghua Gu
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Guiyang Shi
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
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Yang Y, Nie X, Jiang Y, Yang C, Gu Y, Jiang W. Metabolic regulation in solventogenic clostridia: regulators, mechanisms and engineering. Biotechnol Adv 2018; 36:905-914. [DOI: 10.1016/j.biotechadv.2018.02.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/05/2018] [Accepted: 02/20/2018] [Indexed: 12/31/2022]
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42
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Woolston BM, Emerson DF, Currie DH, Stephanopoulos G. Rediverting carbon flux in Clostridium ljungdahlii using CRISPR interference (CRISPRi). Metab Eng 2018; 48:243-253. [PMID: 29906505 DOI: 10.1016/j.ymben.2018.06.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 06/10/2018] [Indexed: 12/28/2022]
Abstract
Clostridium ljungdahlii has emerged as an attractive candidate for the bioconversion of synthesis gas (CO, CO2, H2) to a variety of fuels and chemicals through the Wood-Ljungdahl pathway. However, metabolic engineering and pathway elucidation in this microbe is limited by the lack of genetic tools to downregulate target genes. To overcome this obstacle, here we developed an inducible CRISPR interference (CRISPRi) system for C. ljungdahlii that enables efficient (> 94%) transcriptional repression of several target genes, both individually and in tandem. We then applied CRISPRi in a strain engineered for 3-hydroxybutyrate (3HB) production to examine targets for increasing carbon flux toward the desired product. Downregulating phosphotransacetylase (pta) with a single sgRNA led to a 97% decrease in enzyme activity and a 2.3-fold increase in titer during heterotrophic growth. However, acetate production still accounted for 40% of the carbon flux. Repression of aldehyde:ferredoxin oxidoreductase (aor2), another potential route for acetate production, led to a 5% reduction in acetate flux, whereas using an additional sgRNA targeted to pta reduced the enzyme activity to 0.7% of the wild-type level, and further reduced acetate production to 25% of the carbon flux with an accompanying increase in 3HB titer and yield. These results demonstrate the utility of CRISPRi for elucidating and controlling carbon flow in C. ljungdahlii.
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Affiliation(s)
- Benjamin M Woolston
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, MIT 56-469 C, Cambridge, MA 02139, United States
| | - David F Emerson
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, MIT 56-469 C, Cambridge, MA 02139, United States
| | - Devin H Currie
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, MIT 56-469 C, Cambridge, MA 02139, United States
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, MIT 56-469 C, Cambridge, MA 02139, United States.
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43
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Acetogen Communities in the Gut of Herbivores and Their Potential Role in Syngas Fermentation. FERMENTATION-BASEL 2018. [DOI: 10.3390/fermentation4020040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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44
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Joseph RC, Kim NM, Sandoval NR. Recent Developments of the Synthetic Biology Toolkit for Clostridium. Front Microbiol 2018; 9:154. [PMID: 29483900 PMCID: PMC5816073 DOI: 10.3389/fmicb.2018.00154] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 01/23/2018] [Indexed: 12/15/2022] Open
Abstract
The Clostridium genus is a large, diverse group consisting of Gram-positive, spore-forming, obligate anaerobic firmicutes. Among this group are historically notorious pathogens as well as several industrially relevant species with the ability to produce chemical commodities, particularly biofuels, from renewable biomass. Additionally, other species are studied for their potential use as therapeutics. Although metabolic engineering and synthetic biology have been instrumental in improving product tolerance, titer, yields, and feed stock consumption capabilities in several organisms, low transformation efficiencies and lack of synthetic biology tools and genetic parts make metabolic engineering within the Clostridium genus difficult. Progress has recently been made to overcome challenges associated with engineering various Clostridium spp. For example, developments in CRISPR tools in multiple species and strains allow greater capability to produce edits with greater precision, faster, and with higher efficiencies. In this mini-review, we will highlight these recent advances and compare them to established methods for genetic engineering in Clostridium. In addition, we discuss the current state and development of Clostridium-based promoters (constitutive and inducible) and reporters. Future progress in this area will enable more rapid development of strain engineering, which would allow for the industrial exploitation of Clostridium for several applications including bioproduction of several commodity products.
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Affiliation(s)
- Rochelle C. Joseph
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, United States
| | - Nancy M. Kim
- Interdisciplinary Bioinnovation PhD Program, Tulane University, New Orleans, LA, United States
| | - Nicholas R. Sandoval
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, United States
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45
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Bengelsdorf FR, Beck MH, Erz C, Hoffmeister S, Karl MM, Riegler P, Wirth S, Poehlein A, Weuster-Botz D, Dürre P. Bacterial Anaerobic Synthesis Gas (Syngas) and CO 2+H 2 Fermentation. ADVANCES IN APPLIED MICROBIOLOGY 2018; 103:143-221. [PMID: 29914657 DOI: 10.1016/bs.aambs.2018.01.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Anaerobic bacterial gas fermentation gains broad interest in various scientific, social, and industrial fields. This microbial process is carried out by a specific group of bacterial strains called acetogens. All these strains employ the Wood-Ljungdahl pathway but they belong to different taxonomic groups. Here we provide an overview of the metabolism of acetogens and naturally occurring products. Characteristics of 61 strains were summarized and selected acetogens described in detail. Acetobacterium woodii, Clostridium ljungdahlii, and Moorella thermoacetica serve as model organisms. Results of approaches such as genome-scale modeling, proteomics, and transcriptomics are discussed. Metabolic engineering of acetogens can be used to expand the product portfolio to platform chemicals and to study different aspects of cell physiology. Moreover, the fermentation of gases requires specific reactor configurations and the development of the respective technology, which can be used for an industrial application. Even though the overall process will have a positive effect on climate, since waste and greenhouse gases could be converted into commodity chemicals, some legislative barriers exist, which hamper successful exploitation of this technology.
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Affiliation(s)
- Frank R Bengelsdorf
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany.
| | - Matthias H Beck
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Catarina Erz
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Sabrina Hoffmeister
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Michael M Karl
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Peter Riegler
- Technical University of Munich, Institute of Biochemical Engineering, Garching, Germany
| | - Steffen Wirth
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Anja Poehlein
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University, Göttingen, Germany
| | - Dirk Weuster-Botz
- Technical University of Munich, Institute of Biochemical Engineering, Garching, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
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46
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Joseph RC, Kim NM, Sandoval NR. Recent Developments of the Synthetic Biology Toolkit for Clostridium. Front Microbiol 2018. [PMID: 29483900 DOI: 10.3389/fmicb.2018.00154/full] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
The Clostridium genus is a large, diverse group consisting of Gram-positive, spore-forming, obligate anaerobic firmicutes. Among this group are historically notorious pathogens as well as several industrially relevant species with the ability to produce chemical commodities, particularly biofuels, from renewable biomass. Additionally, other species are studied for their potential use as therapeutics. Although metabolic engineering and synthetic biology have been instrumental in improving product tolerance, titer, yields, and feed stock consumption capabilities in several organisms, low transformation efficiencies and lack of synthetic biology tools and genetic parts make metabolic engineering within the Clostridium genus difficult. Progress has recently been made to overcome challenges associated with engineering various Clostridium spp. For example, developments in CRISPR tools in multiple species and strains allow greater capability to produce edits with greater precision, faster, and with higher efficiencies. In this mini-review, we will highlight these recent advances and compare them to established methods for genetic engineering in Clostridium. In addition, we discuss the current state and development of Clostridium-based promoters (constitutive and inducible) and reporters. Future progress in this area will enable more rapid development of strain engineering, which would allow for the industrial exploitation of Clostridium for several applications including bioproduction of several commodity products.
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Affiliation(s)
- Rochelle C Joseph
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, United States
| | - Nancy M Kim
- Interdisciplinary Bioinnovation PhD Program, Tulane University, New Orleans, LA, United States
| | - Nicholas R Sandoval
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, United States
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47
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Balancing cellular redox metabolism in microbial electrosynthesis and electro fermentation - A chance for metabolic engineering. Metab Eng 2017; 45:109-120. [PMID: 29229581 DOI: 10.1016/j.ymben.2017.12.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/15/2017] [Accepted: 12/06/2017] [Indexed: 01/05/2023]
Abstract
More and more microbes are discovered that are capable of extracellular electron transfer, a process in which they use external electrodes as electron donors or acceptors for metabolic reactions. This feature can be used to overcome cellular redox limitations and thus optimizing microbial production. The technologies, termed microbial electrosynthesis and electro-fermentation, have the potential to open novel bio-electro production platforms from sustainable energy and carbon sources. However, the performance of reported systems is currently limited by low electron transport rates between microbes and electrodes and our limited ability for targeted engineering of these systems due to remaining knowledge gaps about the underlying fundamental processes. Metabolic engineering offers many opportunities to optimize these processes, for instance by genetic engineering of pathways for electron transfer on the one hand and target product synthesis on the other hand. With this review, we summarize the status quo of knowledge and engineering attempts around chemical production in bio-electrochemical systems from a microbe perspective. Challenges associated with the introduction or enhancement of extracellular electron transfer capabilities into production hosts versus the engineering of target compound synthesis pathways in natural exoelectrogens are discussed. Recent advances of the research community in both directions are examined critically. Further, systems biology approaches, for instance using metabolic modelling, are examined for their potential to provide insight into fundamental processes and to identify targets for metabolic engineering.
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Shin HJ, Jung KA, Nam CW, Park JM. A genetic approach for microbial electrosynthesis system as biocommodities production platform. BIORESOURCE TECHNOLOGY 2017; 245:1421-1429. [PMID: 28550992 DOI: 10.1016/j.biortech.2017.05.077] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 05/12/2017] [Accepted: 05/14/2017] [Indexed: 06/07/2023]
Abstract
Microbial electrosynthesis is a process that can produce biocommodities from the reduction of substrates with microbial catalysts and an external electron supply. This process is expected to become a new application of a cell factory for novel chemical production, wastewater treatment, and carbon capture and utilization. However, microbial electrosynthesis is still subject to several problems that need to be overcome for commercialization, so continuous development such as metabolic engineering is essential. The development of microbial electrosynthesis can open up new opportunities for sustainable biocommodities production platforms. This review provides significant information on the current state of MES development, focusing on extracellularly electron transfer and metabolic engineering.
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Affiliation(s)
- Hyo Jeong Shin
- Department of Chemical Engineering, POSTECH, 77 Cheongam-ro, Nam-gu, Pohang 37673, South Korea
| | - Kyung A Jung
- Bioenergy Research Center, POSTECH, 77 Cheongam-ro, Nam-gu, Pohang 37673, South Korea
| | - Chul Woo Nam
- Department of Chemical Engineering, POSTECH, 77 Cheongam-ro, Nam-gu, Pohang 37673, South Korea
| | - Jong Moon Park
- Department of Chemical Engineering, POSTECH, 77 Cheongam-ro, Nam-gu, Pohang 37673, South Korea; Bioenergy Research Center, POSTECH, 77 Cheongam-ro, Nam-gu, Pohang 37673, South Korea; Division of Advanced Nuclear Engineering, POSTECH, 77 Cheongam-ro, Nam-gu, Pohang 37673, South Korea.
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Overcoming the energetic limitations of syngas fermentation. Curr Opin Chem Biol 2017; 41:84-92. [DOI: 10.1016/j.cbpa.2017.10.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 09/28/2017] [Accepted: 10/03/2017] [Indexed: 01/05/2023]
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Transcriptomic profiles of Clostridium ljungdahlii during lithotrophic growth with syngas or H 2 and CO 2 compared to organotrophic growth with fructose. Sci Rep 2017; 7:13135. [PMID: 29030620 PMCID: PMC5640608 DOI: 10.1038/s41598-017-12712-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/14/2017] [Indexed: 01/13/2023] Open
Abstract
Clostridium ljungdahlii derives energy by lithotrophic and organotrophic acetogenesis. C. ljungdahlii was grown organotrophically with fructose and also lithotrophically, either with syngas - a gas mixture containing hydrogen (H2), carbon dioxide (CO2), and carbon monoxide (CO), or with H2 and CO2. Gene expression was compared quantitatively by microarrays using RNA extracted from all three conditions. Gene expression with fructose and with H2/CO2 was compared by RNA-Seq. Upregulated genes with both syngas and H2/CO2 (compared to fructose) point to the urea cycle, uptake and degradation of peptides and amino acids, response to sulfur starvation, potentially NADPH-producing pathways involving (S)-malate and ornithine, quorum sensing, sporulation, and cell wall remodeling, suggesting a global and multicellular response to lithotrophic conditions. With syngas, the upregulated (R)-lactate dehydrogenase gene represents a route of electron transfer from ferredoxin to NAD. With H2/CO2, flavodoxin and histidine biosynthesis genes were upregulated. Downregulated genes corresponded to an intracytoplasmic microcompartment for disposal of methylglyoxal, a toxic byproduct of glycolysis, as 1-propanol. Several cytoplasmic and membrane-associated redox-active protein genes were differentially regulated. The transcriptomic profiles of C. ljungdahlii in lithotrophic and organotrophic growth modes indicate large-scale physiological and metabolic differences, observations that may guide biofuel and commodity chemical production with this species.
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