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202
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Sommer B, Garbe D, Schrepfer P, Brück T. Characterization of a highly thermostable ß-hydroxybutyryl CoA dehydrogenase from Clostridium acetobutylicum ATCC 824. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.molcatb.2013.10.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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203
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Sandoval-Espinola WJ, Makwana ST, Chinn MS, Thon MR, Azcárate-Peril MA, Bruno-Bárcena JM. Comparative phenotypic analysis and genome sequence of Clostridium beijerinckii SA-1, an offspring of NCIMB 8052. MICROBIOLOGY (READING, ENGLAND) 2013; 159:2558-2570. [PMID: 24068240 PMCID: PMC7336276 DOI: 10.1099/mic.0.069534-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 09/24/2013] [Indexed: 01/07/2023]
Abstract
Production of butanol by solventogenic clostridia is controlled through metabolic regulation of the carbon flow and limited by its toxic effects. To overcome cell sensitivity to solvents, stress-directed evolution methodology was used three decades ago on Clostridium beijerinckii NCIMB 8052 that spawned the SA-1 strain. Here, we evaluated SA-1 solventogenic capabilities when growing on a previously validated medium containing, as carbon- and energy-limiting substrates, sucrose and the products of its hydrolysis d-glucose and d-fructose and only d-fructose. Comparative small-scale batch fermentations with controlled pH (pH 6.5) showed that SA-1 is a solvent hyper-producing strain capable of generating up to 16.1 g l(-1) of butanol and 26.3 g l(-1) of total solvents, 62.3 % and 63 % more than NCIMB 8052, respectively. This corresponds to butanol and solvent yields of 0.3 and 0.49 g g(-1), respectively (63 % and 65 % increase compared with NCIMB 8052). SA-1 showed a deficiency in d-fructose transport as suggested by its 7 h generation time compared with 1 h for NCIMB 8052. To potentially correlate physiological behaviour with genetic mutations, the whole genome of SA-1 was sequenced using the Illumina GA IIx platform. PCR and Sanger sequencing were performed to analyse the putative variations. As a result, four errors were confirmed and validated in the reference genome of NCIMB 8052 and a total of 10 genetic polymorphisms in SA-1. The genetic polymorphisms included eight single nucleotide variants, one small deletion and one large insertion that it is an additional copy of the insertion sequence ISCb1. Two of the genetic polymorphisms, the serine threonine phosphatase cbs_4400 and the solute binding protein cbs_0769, may possibly explain some of the observed physiological behaviour, such as rerouting of the metabolic carbon flow, deregulation of the d-fructose phosphotransferase transport system and delayed sporulation.
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Affiliation(s)
| | - Satya T. Makwana
- Department of Microbiology, North Carolina State University, Raleigh, NC 27695-7615, USA
| | - Mari S. Chinn
- Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC 27695-7615, USA
| | - Michael R. Thon
- Centro Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, Calle Del Duero 12, Villamayor 37185, Spain
| | - M. Andrea Azcárate-Peril
- Department of Cell Biology and Physiology, School of Medicine and Microbiome Core Facility, Center for Gastrointestinal Biology and Disease, University of North Carolina, Chapel Hill, NC 27599-7545, USA
| | - José M. Bruno-Bárcena
- Department of Microbiology, North Carolina State University, Raleigh, NC 27695-7615, USA
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204
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Prospective and development of butanol as an advanced biofuel. Biotechnol Adv 2013; 31:1575-84. [DOI: 10.1016/j.biotechadv.2013.08.004] [Citation(s) in RCA: 200] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 07/31/2013] [Accepted: 08/05/2013] [Indexed: 01/26/2023]
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205
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Complete Genome Sequence of the Solvent Producer Clostridium saccharobutylicum NCP262 (DSM 13864). GENOME ANNOUNCEMENTS 2013; 1:1/6/e00997-13. [PMID: 24285650 PMCID: PMC3869335 DOI: 10.1128/genomea.00997-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Clostridium saccharobutylicum was employed for the production of acetone and butanol in South Africa until the 1970s. The genome comprises a single replicon (5,107,814 bp) harboring all the genes necessary for solvent production and the degradation of various organic compounds, such as fructose, cellobiose, sucrose, and mannose.
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206
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σK of Clostridium acetobutylicum is the first known sporulation-specific sigma factor with two developmentally separated roles, one early and one late in sporulation. J Bacteriol 2013; 196:287-99. [PMID: 24187083 DOI: 10.1128/jb.01103-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sporulation in the model endospore-forming organism Bacillus subtilis proceeds via the sequential and stage-specific activation of the sporulation-specific sigma factors, σ(H) (early), σ(F), σ(E), σ(G), and σ(K) (late). Here we show that the Clostridium acetobutylicum σ(K) acts both early, prior to Spo0A expression, and late, past σ(G) activation, thus departing from the B. subtilis model. The C. acetobutylicum sigK deletion (ΔsigK) mutant was unable to sporulate, and solventogenesis, the characteristic stationary-phase phenomenon for this organism, was severely diminished. Transmission electron microscopy demonstrated that the ΔsigK mutant does not develop an asymmetric septum and produces no granulose. Complementation of sigK restored sporulation and solventogenesis to wild-type levels. Spo0A and σ(G) proteins were not detectable by Western analysis, while σ(F) protein levels were significantly reduced in the ΔsigK mutant. spo0A, sigF, sigE, sigG, spoIIE, and adhE1 transcript levels were all downregulated in the ΔsigK mutant, while those of the sigH transcript were unaffected during the exponential and transitional phases of culture. These data show that σ(K) is necessary for sporulation prior to spo0A expression. Plasmid-based expression of spo0A in the ΔsigK mutant from a nonnative promoter restored solventogenesis and the production of Spo0A, σ(F), σ(E), and σ(G), but not sporulation, which was blocked past the σ(G) stage of development, thus demonstrating that σ(K) is also necessary in late sporulation. sigK is expressed very early at low levels in exponential phase but is strongly upregulated during the middle to late stationary phase. This is the first sporulation-specific sigma factor shown to have two developmentally separated roles.
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207
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Tashiro Y, Yoshida T, Noguchi T, Sonomoto K. Recent advances and future prospects for increased butanol production by acetone-butanol-ethanol fermentation. Eng Life Sci 2013. [DOI: 10.1002/elsc.201200128] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Yukihiro Tashiro
- Laboratory of Soil Microbiology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School; Kyushu University; Fukuoka Japan
- Institute of Advanced Study; Kyushu University; Fukuoka Japan
| | - Tsuyoshi Yoshida
- Laboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School; Kyushu University; Fukuoka Japan
| | - Takuya Noguchi
- Laboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School; Kyushu University; Fukuoka Japan
| | - Kenji Sonomoto
- Laboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School; Kyushu University; Fukuoka Japan
- Laboratory of Functional Food Design, Department of Functional Metabolic Design, Bio-Architecture Center; Kyushu University; Fukuoka Japan
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208
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Wegmann U, Louis P, Goesmann A, Henrissat B, Duncan SH, Flint HJ. Complete genome of a new Firmicutes species belonging to the dominant human colonic microbiota ('Ruminococcus bicirculans') reveals two chromosomes and a selective capacity to utilize plant glucans. Environ Microbiol 2013; 16:2879-90. [PMID: 23919528 DOI: 10.1111/1462-2920.12217] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 06/28/2013] [Accepted: 07/14/2013] [Indexed: 01/22/2023]
Abstract
The recently isolated bacterial strain 80/3 represents one of the most abundant 16S rRNA phylotypes detected in the healthy human large intestine and belongs to the Ruminococcaceae family of Firmicutes. The completed genome sequence reported here is the first for a member of this important family of bacteria from the human colon. The genome comprises two large chromosomes of 2.24 and 0.73 Mbp, leading us to propose the name Ruminococcus bicirculans for this new species. Analysis of the carbohydrate active enzyme complement suggests an ability to utilize certain hemicelluloses, especially β-glucans and xyloglucan, for growth that was confirmed experimentally. The enzymatic machinery enabling the degradation of cellulose and xylan by related cellulolytic ruminococci is however lacking in this species. While the genome indicated the capacity to synthesize purines, pyrimidines and all 20 amino acids, only genes for the synthesis of nicotinate, NAD+, NADP+ and coenzyme A were detected among the essential vitamins and co-factors, resulting in multiple growth requirements. In vivo, these growth factors must be supplied from the diet, host or other gut microorganisms. Other features of ecological interest include two type IV pilins, multiple extracytoplasmic function-sigma factors, a urease and a bile salt hydrolase.
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Affiliation(s)
- Udo Wegmann
- Gut Health and Food Safety Programme, Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK
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209
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Genome Sequence of Thermus thermophilus ATCC 33923, a Thermostable Trehalose-Producing Strain. GENOME ANNOUNCEMENTS 2013; 1:1/4/e00493-13. [PMID: 23887916 PMCID: PMC3735056 DOI: 10.1128/genomea.00493-13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Thermus thermophilus ATCC 33923 contains a thermostable enzyme that can efficiently catalyze the conversion of maltose into trehalose. Here we report a 2.15-Mb assembly of its genome sequence and other useful information, including the coding sequences (CDS) responsible for biological processes such as DNA replication, DNA repair, and RNA maturation.
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210
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Schiel-Bengelsdorf B, Montoya J, Linder S, Dürre P. Butanol fermentation. ENVIRONMENTAL TECHNOLOGY 2013; 34:1691-1710. [PMID: 24350428 DOI: 10.1080/09593330.2013.827746] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This review provides an overview on bacterial butanol production and recent developments concerning strain improvement, newly built butanol production plants, and the importance of alternative substrates, especially lignocellulosic hydrolysates. The butanol fermentation using solventogenic clostridial strains, particularly Clostridium acetobutylicum, is a very old industrial process (acetone-butanol-ethanol-ABE fermentation). The genome of this organism has been sequenced and analysed, leading to important improvements in rational strain construction. As the traditional ABE fermentation process is economically unfavourable, novel butanol production strains are being developed. In this review, some newly engineered solvent-producing Clostridium strains are described and strains of which sequences are available are compared with C. acetobutylicum. Furthermore, the past and present of commercial butanol fermentation are presented, including active plants and companies. Finally, the use of biomass as substrate for butanol production is discussed. Some advances concerning processing of biomass in a biorefinery are highlighted, which would allow lowering the price of the butanol fermentation process at industrial scale.
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Affiliation(s)
- Bettina Schiel-Bengelsdorf
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - José Montoya
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Sonja Linder
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
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211
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Enhancement of ABE fermentation through regulation of ammonium acetate and D–xylose uptake from acid-pretreated corncobs. ANN MICROBIOL 2013. [DOI: 10.1007/s13213-013-0673-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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212
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Effect of an oxygen-tolerant bifurcating butyryl coenzyme A dehydrogenase/electron-transferring flavoprotein complex from Clostridium difficile on butyrate production in Escherichia coli. J Bacteriol 2013; 195:3704-13. [PMID: 23772070 DOI: 10.1128/jb.00321-13] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The butyrogenic genes from Clostridium difficile DSM 1296(T) have been cloned and expressed in Escherichia coli. The enzymes acetyl-coenzyme A (CoA) C-acetyltransferase, 3-hydroxybutyryl-CoA dehydrogenase, crotonase, phosphate butyryltransferase, and butyrate kinase and the butyryl-CoA dehydrogenase complex composed of the dehydrogenase and two electron-transferring flavoprotein subunits were individually produced in E. coli and kinetically characterized in vitro. While most of these enzymes were measured using well-established test systems, novel methods to determine butyrate kinase and butyryl-CoA dehydrogenase activities with respect to physiological function were developed. Subsequently, the individual genes were combined to form a single plasmid-encoded operon in a plasmid vector, which was successfully used to confer butyrate-forming capability to the host. In vitro and in vivo studies demonstrated that C. difficile possesses a bifurcating butyryl-CoA dehydrogenase which catalyzes the NADH-dependent reduction of ferredoxin coupled to the reduction of crotonyl-CoA also by NADH. Since the reoxidation of ferredoxin by a membrane-bound ferredoxin:NAD(+)-oxidoreductase enables electron transport phosphorylation, additional ATP is formed. The butyryl-CoA dehydrogenase from C. difficile is oxygen stable and apparently uses oxygen as a co-oxidant of NADH in the presence of air. These properties suggest that this enzyme complex might be well suited to provide butyryl-CoA for solventogenesis in recombinant strains. The central role of bifurcating butyryl-CoA dehydrogenases and membrane-bound ferredoxin:NAD oxidoreductases (Rhodobacter nitrogen fixation [RNF]), which affect the energy yield of butyrate fermentation in the clostridial metabolism, is discussed.
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213
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Hou S, Jones SW, Choe LH, Papoutsakis ET, Lee KH. Workflow for quantitative proteomic analysis of Clostridium acetobutylicum ATCC 824 using iTRAQ tags. Methods 2013; 61:269-76. [DOI: 10.1016/j.ymeth.2013.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 02/21/2013] [Accepted: 03/12/2013] [Indexed: 11/16/2022] Open
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214
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Genome Sequence of Clostridium tyrobutyricum ATCC 25755, a Butyric Acid-Overproducing Strain. GENOME ANNOUNCEMENTS 2013; 1:1/3/e00308-13. [PMID: 23723404 PMCID: PMC3668012 DOI: 10.1128/genomea.00308-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Clostridium tyrobutyricum ATCC 25755 is an efficient producer of butyric acid. Here we report a 3.01-Mb assembly of its genome sequence and other useful information, including the coding sequences (CDSs) responsible for an alternative pathway leading to acetate synthesis as well as a series of membrane transport systems.
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215
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Yang L, Bao G, Zhu Y, Dong H, Zhang Y, Li Y. Discovery of a novel gene involved in autolysis of Clostridium cells. Protein Cell 2013; 4:467-74. [PMID: 23702687 DOI: 10.1007/s13238-013-3025-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 04/25/2013] [Indexed: 01/08/2023] Open
Abstract
Cell autolysis plays important physiological roles in the life cycle of clostridial cells. Understanding the genetic basis of the autolysis phenomenon of pathogenic Clostridium or solvent producing Clostridium cells might provide new insights into this important species. Genes that might be involved in autolysis of Clostridium acetobutylicum, a model clostridial species, were investigated in this study. Twelve putative autolysin genes were predicted in C. acetobutylicum DSM 1731 genome through bioinformatics analysis. Of these 12 genes, gene SMB_G3117 was selected for testing the in tracellular autolysin activity, growth profile, viable cell numbers, and cellular morphology. We found that overexpression of SMB_G3117 gene led to earlier ceased growth, significantly increased number of dead cells, and clear electrolucent cavities, while disruption of SMB_G3117 gene exhibited remarkably reduced intracellular autolysin activity. These results indicate that SMB_G3117 is a novel gene involved in cellular autolysis of C. acetobutylicum.
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Affiliation(s)
- Liejian Yang
- Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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216
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Xu C, Huang R, Teng L, Wang D, Hemme CL, Borovok I, He Q, Lamed R, Bayer EA, Zhou J, Xu J. Structure and regulation of the cellulose degradome in Clostridium cellulolyticum. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:73. [PMID: 23657055 PMCID: PMC3656788 DOI: 10.1186/1754-6834-6-73] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 05/01/2013] [Indexed: 05/20/2023]
Abstract
BACKGROUND Many bacteria efficiently degrade lignocellulose yet the underpinning genome-wide metabolic and regulatory networks remain elusive. Here we revealed the "cellulose degradome" for the model mesophilic cellulolytic bacterium Clostridium cellulolyticum ATCC 35319, via an integrated analysis of its complete genome, its transcriptomes under glucose, xylose, cellobiose, cellulose, xylan or corn stover and its extracellular proteomes under glucose, cellobiose or cellulose. RESULTS Proteins for core metabolic functions, environment sensing, gene regulation and polysaccharide metabolism were enriched in the cellulose degradome. Analysis of differentially expressed genes revealed a "core" set of 48 CAZymes required for degrading cellulose-containing substrates as well as an "accessory" set of 76 CAZymes required for specific non-cellulose substrates. Gene co-expression analysis suggested that Carbon Catabolite Repression (CCR) related regulators sense intracellular glycolytic intermediates and control the core CAZymes that mainly include cellulosomal components, whereas 11 sets of Two-Component Systems (TCSs) respond to availability of extracellular soluble sugars and respectively regulate most of the accessory CAZymes and associated transporters. Surprisingly, under glucose alone, the core cellulases were highly expressed at both transcript and protein levels. Furthermore, glucose enhanced cellulolysis in a dose-dependent manner, via inducing cellulase transcription at low concentrations. CONCLUSION A molecular model of cellulose degradome in C. cellulolyticum (Ccel) was proposed, which revealed the substrate-specificity of CAZymes and the transcriptional regulation of core cellulases by CCR where the glucose acts as a CCR inhibitor instead of a trigger. These features represent a distinct environment-sensing strategy for competing while collaborating for cellulose utilization, which can be exploited for process and genetic engineering of microbial cellulolysis.
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Affiliation(s)
- Chenggang Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Ranran Huang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Lin Teng
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Dongmei Wang
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Christopher L Hemme
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73072, USA
| | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Qiang He
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Edward A Bayer
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73072, USA
| | - Jian Xu
- BioEnergy Genome Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
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217
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Jabbari S, Steiner E, Heap JT, Winzer K, Minton NP, King JR. The putative influence of the agr operon upon survival mechanisms used by Clostridium acetobutylicum. Math Biosci 2013; 243:223-39. [PMID: 23538287 DOI: 10.1016/j.mbs.2013.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 03/04/2013] [Accepted: 03/12/2013] [Indexed: 10/27/2022]
Abstract
The bacterium Clostridium acetobutylicum produces acids as an energy-yielding process during exponential growth. An acidic environment, however, is toxic to the cells and two survival mechanisms are in place to prevent them from dying. Firstly, during a solventogenesis phase, the cells take up these acids and convert them to solvents, thus raising the environmental pH. Secondly, the cells undergo sporulation to form highly resistant spores capable of surviving extreme conditions. One possible regulatory mechanism for these processes is the accessory gene regulatory (agr) quorum-sensing system, which is thought to coordinate cell population density with cell phenotype. We model this system to monitor its putative effect upon solventogenesis and the sporulation-initiation network responsible for triggering spore formation. We demonstrate that a high population density should be able to induce both solventogenesis and sporulation, with variations to the parameter set allowing sporulation alone to be triggered; additional distinct signals are capable of restoring the solventogenic response. We compare the agr system of C. acetobutylicum with that of Staphylococcus aureus in order to investigate why the differences in feedback between the two systems may have evolved. Our findings indicate that, depending upon the mechanism of interaction between the agr system and the sporulation-initiation network, the clostridial agr circuitry may be in place either to moderate the number of spores that are formed (in order for this number to reflect the urgency of the situation), or simply as an energy-saving strategy.
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Affiliation(s)
- Sara Jabbari
- School of Mathematics and Centre for Systems Biology, University of Birmingham, Edgbaston Campus, Birmingham B15 2TT, UK.
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218
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Van Dien S. From the first drop to the first truckload: commercialization of microbial processes for renewable chemicals. Curr Opin Biotechnol 2013; 24:1061-8. [PMID: 23537815 DOI: 10.1016/j.copbio.2013.03.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/27/2013] [Accepted: 03/05/2013] [Indexed: 01/24/2023]
Abstract
Fermentation of carbohydrate substrates by microorganisms represents an attractive route for the manufacture of industrial chemicals from renewable resources. The technology to manipulate metabolism of bacteria and yeast, including the introduction of heterologous chemical pathways, has accelerated research in this field. However, the public literature contains very few examples of strains achieving the production metrics required for commercialization. This article presents the challenges in reaching commercial titer, yield, and productivity targets, along with other necessary strain and process characteristics. It then reviews various methods in systems biology, synthetic biology, enzyme engineering, and fermentation engineering which can be applied to strain improvement, and presents a strategy for using these tools to overcome the major hurdles on the path to commercialization.
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Affiliation(s)
- Stephen Van Dien
- Genomatica, Inc., 10520 Wateridge Circle, San Diego, CA 92121, United States.
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219
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Gao W, Francis AJ. Fermentation and hydrogen metabolism affect uranium reduction by clostridia. ISRN BIOTECHNOLOGY 2013; 2013:657160. [PMID: 25937978 PMCID: PMC4393052 DOI: 10.5402/2013/657160] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 01/19/2013] [Indexed: 11/23/2022]
Abstract
Previously, it has been shown that not only is uranium reduction under fermentation condition common among clostridia species, but also the strains differed in the extent of their capability and the pH of the culture significantly affected uranium(VI) reduction. In this study, using HPLC and GC techniques, metabolic properties of those clostridial strains active in uranium reduction under fermentation conditions have been characterized and their effects on capability variance of uranium reduction discussed. Then, the relationship between hydrogen metabolism and uranium reduction has been further explored and the important role played by hydrogenase in uranium(VI) and iron(III) reduction by clostridia demonstrated. When hydrogen was provided as the headspace gas, uranium(VI) reduction occurred in the presence of whole cells of clostridia. This is in contrast to that of nitrogen as the headspace gas. Without clostridia cells, hydrogen alone could not result in uranium(VI) reduction. In alignment with this observation, it was also found that either copper(II) addition or iron depletion in the medium could compromise uranium reduction by clostridia. In the end, a comprehensive model was proposed to explain uranium reduction by clostridia and its relationship to the overall metabolism especially hydrogen (H2) production.
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Affiliation(s)
- Weimin Gao
- Center for Biosignatures Discovery Automation, Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
| | - Arokiasamy J. Francis
- Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
- Environmental Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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220
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Characterization of a novel metagenome-derived 6-phospho-β-glucosidase from black liquor sediment. Appl Environ Microbiol 2013; 79:2121-7. [PMID: 23335769 DOI: 10.1128/aem.03528-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enzyme 6-phospho-β-glucosidase is an important member of the glycoside hydrolase family 1 (GH1). However, its catalytic mechanisms, especially the key residues determining substrate specificity and affinity, are poorly understood. A metagenome-derived gene sequence, encoding a novel 6-phospho-β-glucosidase designated Pbgl25-217, was isolated and characterized. The optimal conditions for enzymatic activity were 37°C and pH 7; Ca(2+), Mg(2+), and Mn(2+) stabilized the activity of Pbgl25-217, whereas Ni(2+), Fe(2+), Zn(2+), Cu(2+), and Fe(3+) inhibited its activity. The Km and Vmax of Pbgl25-217 were 4.8 mM and 1,987.0 U mg(-1), respectively. Seven conserved residues were recognized by multiple alignments and were tested by site-directed mutagenesis for their functions in substrate recognition and catalytic reaction. The results suggest that residues S427, Lys435, and Tyr437 act as "gatekeepers" in a phosphate-binding loop and play important roles in phosphate recognition. This functional identification may provide insights into the specificity of 6-phospho-β-glycosidases in GH1 and be useful for designing further directed evolution.
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Letzel AC, Pidot SJ, Hertweck C. A genomic approach to the cryptic secondary metabolome of the anaerobic world. Nat Prod Rep 2012; 30:392-428. [PMID: 23263685 DOI: 10.1039/c2np20103h] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A total of 211 complete and published genomes from anaerobic bacteria are analysed for the presence of secondary metabolite biosynthesis gene clusters, in particular those tentatively coding for polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS). We investigate the distribution of these gene clusters according to bacterial phylogeny and, if known, correlate these to the type of metabolic pathways they encode. The potential of anaerobes as secondary metabolite producers is highlighted.
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Affiliation(s)
- Anne-Catrin Letzel
- Leibniz Institute for Natural Product Research and Infection Biology HKI, Beutenbergstr. 11a, Jena, 07745, Germany
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Wolf YI, Makarova KS, Yutin N, Koonin EV. Updated clusters of orthologous genes for Archaea: a complex ancestor of the Archaea and the byways of horizontal gene transfer. Biol Direct 2012; 7:46. [PMID: 23241446 PMCID: PMC3534625 DOI: 10.1186/1745-6150-7-46] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 12/11/2012] [Indexed: 12/17/2022] Open
Abstract
Background Collections of Clusters of Orthologous Genes (COGs) provide indispensable tools for comparative genomic analysis, evolutionary reconstruction and functional annotation of new genomes. Initially, COGs were made for all complete genomes of cellular life forms that were available at the time. However, with the accumulation of thousands of complete genomes, construction of a comprehensive COG set has become extremely computationally demanding and prone to error propagation, necessitating the switch to taxon-specific COG collections. Previously, we reported the collection of COGs for 41 genomes of Archaea (arCOGs). Here we present a major update of the arCOGs and describe evolutionary reconstructions to reveal general trends in the evolution of Archaea. Results The updated version of the arCOG database incorporates 91% of the pangenome of 120 archaea (251,032 protein-coding genes altogether) into 10,335 arCOGs. Using this new set of arCOGs, we performed maximum likelihood reconstruction of the genome content of archaeal ancestral forms and gene gain and loss events in archaeal evolution. This reconstruction shows that the last Common Ancestor of the extant Archaea was an organism of greater complexity than most of the extant archaea, probably with over 2,500 protein-coding genes. The subsequent evolution of almost all archaeal lineages was apparently dominated by gene loss resulting in genome streamlining. Overall, in the evolution of Archaea as well as a representative set of bacteria that was similarly analyzed for comparison, gene losses are estimated to outnumber gene gains at least 4 to 1. Analysis of specific patterns of gene gain in Archaea shows that, although some groups, in particular Halobacteria, acquire substantially more genes than others, on the whole, gene exchange between major groups of Archaea appears to be largely random, with no major ‘highways’ of horizontal gene transfer. Conclusions The updated collection of arCOGs is expected to become a key resource for comparative genomics, evolutionary reconstruction and functional annotation of new archaeal genomes. Given that, in spite of the major increase in the number of genomes, the conserved core of archaeal genes appears to be stabilizing, the major evolutionary trends revealed here have a chance to stand the test of time. Reviewers This article was reviewed by (for complete reviews see the Reviewers’ Reports section): Dr. PLG, Prof. PF, Dr. PL (nominated by Prof. JPG).
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Affiliation(s)
- Yuri I Wolf
- National Center for Biotechnology Information, NLM, National Institutes of Health, Bethesda, MD 20894, USA.
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The purine-utilizing bacterium Clostridium acidurici 9a: a genome-guided metabolic reconsideration. PLoS One 2012; 7:e51662. [PMID: 23240052 PMCID: PMC3519856 DOI: 10.1371/journal.pone.0051662] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 11/06/2012] [Indexed: 11/19/2022] Open
Abstract
Clostridium acidurici is an anaerobic, homoacetogenic bacterium, which is able to use purines such as uric acid as sole carbon, nitrogen, and energy source. Together with the two other known purinolytic clostridia C. cylindrosporum and C. purinilyticum, C. acidurici serves as a model organism for investigation of purine fermentation. Here, we present the first complete sequence and analysis of a genome derived from a purinolytic Clostridium. The genome of C. acidurici 9a consists of one chromosome (3,105,335 bp) and one small circular plasmid (2,913 bp). The lack of candidate genes encoding glycine reductase indicates that C. acidurici 9a uses the energetically less favorable glycine-serine-pyruvate pathway for glycine degradation. In accordance with the specialized lifestyle and the corresponding narrow substrate spectrum of C. acidurici 9a, the number of genes involved in carbohydrate transport and metabolism is significantly lower than in other clostridia such as C. acetobutylicum, C. saccharolyticum, and C. beijerinckii. The only amino acid that can be degraded by C. acidurici is glycine but growth on glycine only occurs in the presence of a fermentable purine. Nevertheless, the addition of glycine resulted in increased transcription levels of genes encoding enzymes involved in the glycine-serine-pyruvate pathway such as serine hydroxymethyltransferase and acetate kinase, whereas the transcription levels of formate dehydrogenase-encoding genes decreased. Sugars could not be utilized by C. acidurici but the full genetic repertoire for glycolysis was detected. In addition, genes encoding enzymes that mediate resistance against several antimicrobials and metals were identified. High resistance of C. acidurici towards bacitracin, acriflavine and azaleucine was experimentally confirmed.
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Li X, Li Z, Zheng J, Shi Z, Li L. Yeast extract promotes phase shift of bio-butanol fermentation by Clostridium acetobutylicum ATCC824 using cassava as substrate. BIORESOURCE TECHNOLOGY 2012; 125:43-51. [PMID: 23023236 DOI: 10.1016/j.biortech.2012.08.056] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Revised: 08/11/2012] [Accepted: 08/14/2012] [Indexed: 05/12/2023]
Abstract
When fermenting on cassava (15-25%, w/v) with Clostridium acetobutylicum ATCC824, a severe delay (18-40 h) was observed in the phase shift from acidogenesis to solventogenesis, compared to the cases of fermenting on corn. By adding yeast extract (2.5 g/L-broth) into cassava meal medium when the delay appeared, the phase shift was triggered and fermentation performances were consequently improved. Total butanol concentrations/butanol productivities, compared to those with cassava substrate alone, increased 15%/80% in traditional fermentation while 86%/79% in extractive fermentation using oleyl alcohol as the extractant, and reached the equivalent levels of those using corn substrate. Analysis of genetic transcriptional levels and measurements of free amino acids in the broth demonstrated that timely and adequate addition of yeast extract could promote phase shift by increasing transcriptional level of ctfAB to 16-fold, and indirectly enhance butanol synthesis through accelerating the accumulation of histidine and aspartic acid families.
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Affiliation(s)
- Xin Li
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
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Mann MS, Lütke-Eversloh T. Thiolase engineering for enhanced butanol production in Clostridium acetobutylicum. Biotechnol Bioeng 2012; 110:887-97. [PMID: 23096577 DOI: 10.1002/bit.24758] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 10/01/2012] [Accepted: 10/12/2012] [Indexed: 12/20/2022]
Abstract
Biosynthetic thiolases catalyze the condensation of two molecules acetyl-CoA to acetoacetyl-CoA and represent key enzymes for carbon-carbon bond forming metabolic pathways. An important biotechnological example of such a pathway is the clostridial n-butanol production, comprising various natural constraints that limit titer, yield, and productivity. In this study, the thiolase of Clostridium acetobutylicum, the model organism for solventogenic clostridia, was specifically engineered for reduced sensitivity towards its physiological inhibitor coenzyme A (CoA-SH). A high-throughput screening assay in 96-well microtiter plates was developed employing Escherichia coli as host cells for expression of a mutant thiolase gene library. Screening of this library resulted in the identification of a thiolase derivative with significantly increased activity in the presence of free CoA-SH. This optimized thiolase comprised three amino acid substitutions (R133G, H156N, G222V) and its gene was expressed in C. acetobutylicum ATCC 824 to assess the effect of reduced CoA-SH sensitivity on solvent production. In addition to a clearly delayed ethanol and acetone formation, the ethanol and butanol titers were increased by 46% and 18%, respectively, while the final acetone concentrations were similar to the vector control strain. These results demonstrate that thiolase engineering constitutes a suitable methodology applicable to improve clostridial butanol production, but other biosynthetic pathways involving thiolase-mediated carbon flux limitations might also be subjected to this new metabolic engineering approach.
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Affiliation(s)
- Miriam S Mann
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Rostock, Germany
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Enhanced butanol production obtained by reinforcing the direct butanol-forming route in Clostridium acetobutylicum. mBio 2012; 3:mBio.00314-12. [PMID: 23093384 PMCID: PMC3482502 DOI: 10.1128/mbio.00314-12] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Butanol is an important industrial solvent and advanced biofuel that can be produced by biphasic fermentation by Clostridium acetobutylicum. It has been known that acetate and butyrate first formed during the acidogenic phase are reassimilated to form acetone-butanol-ethanol (cold channel). Butanol can also be formed directly from acetyl-coenzyme A (CoA) through butyryl-CoA (hot channel). However, little is known about the relative contributions of the two butanol-forming pathways. Here we report that the direct butanol-forming pathway is a better channel to optimize for butanol production through metabolic flux and mass balance analyses. Butanol production through the hot channel was maximized by simultaneous disruption of the pta and buk genes, encoding phosphotransacetylase and butyrate kinase, while the adhE1D485G gene, encoding a mutated aldehyde/alcohol dehydrogenase, was overexpressed. The ratio of butanol produced through the hot channel to that produced through the cold channel increased from 2.0 in the wild type to 18.8 in the engineered BEKW(pPthlAAD**) strain. By reinforcing the direct butanol-forming flux in C. acetobutylicum, 18.9 g/liter of butanol was produced, with a yield of 0.71 mol butanol/mol glucose by batch fermentation, levels which are 160% and 245% higher than those obtained with the wild type. By fed-batch culture of this engineered strain with in situ recovery, 585.3 g of butanol was produced from 1,861.9 g of glucose, with the yield of 0.76 mol butanol/mol glucose and productivity of 1.32 g/liter/h. Studies of two butanol-forming routes and their effects on butanol production in C. acetobutylicum described here will serve as a basis for further metabolic engineering of clostridia aimed toward developing a superior butanol producer. Renewable biofuel is one of the answers to solving the energy crisis and climate change problems. Butanol produced naturally by clostridia has superior liquid fuel characteristics and thus has the potential to replace gasoline. Due to the lack of efficient genetic manipulation tools, however, strain improvement has been rather slow. Furthermore, complex metabolic characteristics of acidogenesis followed by solventogenesis in this strain have hampered development of engineered clostridia having highly efficient and selective butanol production capability. Here we report for the first time the results of systems metabolic engineering studies of two butanol-forming routes and their relative importances in butanol production. Based on these findings, a metabolically engineered Clostridium acetobutylicum strain capable of producing butanol to a high titer with high yield and selectivity could be developed by reinforcing the direct butanol-forming flux.
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Janssen H, Grimmler C, Ehrenreich A, Bahl H, Fischer RJ. A transcriptional study of acidogenic chemostat cells of Clostridium acetobutylicum—Solvent stress caused by a transient n-butanol pulse. J Biotechnol 2012; 161:354-65. [DOI: 10.1016/j.jbiotec.2012.03.027] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/15/2012] [Accepted: 03/16/2012] [Indexed: 12/30/2022]
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Cooksley CM, Zhang Y, Wang H, Redl S, Winzer K, Minton NP. Targeted mutagenesis of the Clostridium acetobutylicum acetone-butanol-ethanol fermentation pathway. Metab Eng 2012; 14:630-41. [PMID: 22982601 DOI: 10.1016/j.ymben.2012.09.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 08/30/2012] [Accepted: 09/06/2012] [Indexed: 01/29/2023]
Abstract
The production of the chemical solvents acetone and butanol by the bacterium Clostridium acetobutylicum was one of the first large-scale industrial processes to be developed, and in the first part of the last century ranked second in importance only to ethanol production. After a steep decline in its industrial use, there has been a recent resurgence of interest in the acetone-butanol-ethanol (ABE) fermentation process, with a particular emphasis on butanol production. In order to generate strains suitable for efficient use on an industrial scale, metabolic engineering is required to alter the AB ratio in favour of butanol, and eradicate the production of unwanted products of fermentation. Using ClosTron technology, a large-scale targeted mutagenesis in C. acetobutylicum ATCC 824 was carried out, generating a set of 10 mutants, defective in alcohol/aldehyde dehydrogenases 1 and 2 (adhE1, adhE2), butanol dehydrogenases A and B (bdhA, bdhB), phosphotransbutyrylase (ptb), acetate kinase (ack), acetoacetate decarboxylase (adc), CoA transferase (ctfA/ctfB), and a previously uncharacterised putative alcohol dehydrogenase (CAP0059). However, inactivation of the main hydrogenase (hydA) and thiolase (thl) could not be achieved. Constructing such a series of mutants is paramount for the acquisition of information on the mechanism of solvent production in this organism, and the subsequent development of industrial solvent producing strains. Unexpectedly, bdhA and bdhB mutants did not affect solvent production, whereas inactivation of the previously uncharacterised gene CAP0059 resulted in increased acetone, butanol, and ethanol formation. Other mutants showed predicted phenotypes, including a lack of acetone formation (adc, ctfA, and ctfB mutants), an inability to take up acids (ctfA and ctfB mutants), and a much reduced acetate formation (ack mutant). The adhE1 mutant in particular produced very little solvents, demonstrating that this gene was indeed the main contributor to ethanol and butanol formation under the standard batch culture conditions employed in this study. All phenotypic changes observed could be reversed by genetic complementation, with exception of those seen for the ptb mutant. This mutant produced around 100 mM ethanol, no acetone and very little (7 mM) butanol. The genome of the ptb mutant was therefore re-sequenced, together with its parent strain (ATCC 824 wild type), and shown to possess a frameshift mutation in the thl gene, which perfectly explained the observed phenotype. This finding reinforces the need for mutant complementation and Southern Blot analysis (to confirm single ClosTron insertions), which should be obligatory in all further ClosTron applications.
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Affiliation(s)
- Clare M Cooksley
- Clostridia Research Group, BBSRC Sustainable Bioenergy Centre, School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
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Kubiak P, Leja K, Myszka K, Celińska E, Spychała M, Szymanowska-Powałowska D, Czaczyk K, Grajek W. Physiological predisposition of various Clostridium species to synthetize 1,3-propanediol from glycerol. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.05.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Bassi D, Cappa F, Cocconcelli PS. Array-based transcriptional analysis of Clostridium sporogenes UC9000 during germination, cell outgrowth and vegetative life. Food Microbiol 2012; 33:11-23. [PMID: 23122496 DOI: 10.1016/j.fm.2012.08.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/04/2012] [Accepted: 08/05/2012] [Indexed: 01/22/2023]
Abstract
The members of the genus Clostridium, including the spore-forming anaerobic bacteria, have a complex and strictly regulated life cycle, but very little is known about the genetic pathways involved in the different stages of their life cycle. Clostridium sporogenes, a Gram-positive bacterium usually involved in food spoilage and frequently isolated from late blowing cheese, is genetically indistinguishable from the proteolytic Clostridium botulinum. As the non-neurotoxic counterpart, it is often used as an exemplar for the toxic subtypes. In this work, we performed a microscopic study combined with a custom array-based analysis of the C. sporogenes cycle, from dormant spores to the early stationary phase. We identified a total of 211 transcripts in spores, validating the hypothesis that mRNAs are abundant in spores and the pattern of mRNA expression is strikingly different from that present in growing cells. The spore transcripts included genes responsible for different life-sustaining functions, suggesting there was transcript entrapment or basic poly-functional gene activation for future steps. In addition, 3 h after the beginning of the germination process, 20% of the total up-regulated genes were temporally expressed in germinating spores. The vegetative condition appeared to be more active in terms of gene transcription and protein synthesis than the spore, and genes coding for germination and sporulation factors seemed to be expressed at this point. These results suggest that spores are not silent entities, and a broader knowledge of the genetic pathways involved in the Clostridium life cycle could provide a better understanding of pathogenic clostridia types.
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Affiliation(s)
- Daniela Bassi
- Istituto di Microbiologia, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza/Via Milano 24, 26100 Cremona, Italy.
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Phosphoketolase pathway for xylose catabolism in Clostridium acetobutylicum revealed by 13C metabolic flux analysis. J Bacteriol 2012; 194:5413-22. [PMID: 22865845 DOI: 10.1128/jb.00713-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Solvent-producing clostridia are capable of utilizing pentose sugars, including xylose and arabinose; however, little is known about how pentose sugars are catabolized through the metabolic pathways in clostridia. In this study, we identified the xylose catabolic pathways and quantified their fluxes in Clostridium acetobutylicum based on [1-(13)C]xylose labeling experiments. The phosphoketolase pathway was found to be active, which contributed up to 40% of the xylose catabolic flux in C. acetobutylicum. The split ratio of the phosphoketolase pathway to the pentose phosphate pathway was markedly increased when the xylose concentration in the culture medium was increased from 10 to 20 g liter(-1). To our knowledge, this is the first time that the in vivo activity of the phosphoketolase pathway in clostridia has been revealed. A phosphoketolase from C. acetobutylicum was purified and characterized, and its activity with xylulose-5-P was verified. The phosphoketolase was overexpressed in C. acetobutylicum, which resulted in slightly increased xylose consumption rates during the exponential growth phase and a high level of acetate accumulation.
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Pleiotropic functions of catabolite control protein CcpA in Butanol-producing Clostridium acetobutylicum. BMC Genomics 2012; 13:349. [PMID: 22846451 PMCID: PMC3507653 DOI: 10.1186/1471-2164-13-349] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 06/28/2012] [Indexed: 12/24/2022] Open
Abstract
Background Clostridium acetobutylicum has been used to produce butanol in industry. Catabolite control protein A (CcpA), known to mediate carbon catabolite repression (CCR) in low GC gram-positive bacteria, has been identified and characterized in C. acetobutylicum by our previous work (Ren, C. et al. 2010, Metab Eng 12:446–54). To further dissect its regulatory function in C. acetobutylicum, CcpA was investigated using DNA microarray followed by phenotypic, genetic and biochemical validation. Results CcpA controls not only genes in carbon metabolism, but also those genes in solvent production and sporulation of the life cycle in C. acetobutylicum: i) CcpA directly repressed transcription of genes related to transport and metabolism of non-preferred carbon sources such as d-xylose and l-arabinose, and activated expression of genes responsible for d-glucose PTS system; ii) CcpA is involved in positive regulation of the key solventogenic operon sol (adhE1-ctfA-ctfB) and negative regulation of acidogenic gene bukII; and iii) transcriptional alterations were observed for several sporulation-related genes upon ccpA inactivation, which may account for the lower sporulation efficiency in the mutant, suggesting CcpA may be necessary for efficient sporulation of C. acetobutylicum, an important trait adversely affecting the solvent productivity. Conclusions This study provided insights to the pleiotropic functions that CcpA displayed in butanol-producing C. acetobutylicum. The information could be valuable for further dissecting its pleiotropic regulatory mechanism in C. acetobutylicum, and for genetic modification in order to obtain more effective butanol-producing Clostridium strains.
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Buckel W, Thauer RK. Energy conservation via electron bifurcating ferredoxin reduction and proton/Na(+) translocating ferredoxin oxidation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:94-113. [PMID: 22800682 DOI: 10.1016/j.bbabio.2012.07.002] [Citation(s) in RCA: 508] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/05/2012] [Accepted: 07/07/2012] [Indexed: 01/21/2023]
Abstract
The review describes four flavin-containing cytoplasmatic multienzyme complexes from anaerobic bacteria and archaea that catalyze the reduction of the low potential ferredoxin by electron donors with higher potentials, such as NAD(P)H or H(2) at ≤ 100 kPa. These endergonic reactions are driven by concomitant oxidation of the same donor with higher potential acceptors such as crotonyl-CoA, NAD(+) or heterodisulfide (CoM-S-S-CoB). The process called flavin-based electron bifurcation (FBEB) can be regarded as a third mode of energy conservation in addition to substrate level phosphorylation (SLP) and electron transport phosphorylation (ETP). FBEB has been detected in the clostridial butyryl-CoA dehydrogenase/electron transferring flavoprotein complex (BcdA-EtfBC), the multisubunit [FeFe]hydrogenase from Thermotoga maritima (HydABC) and from acetogenic bacteria, the [NiFe]hydrogenase/heterodisulfide reductase (MvhADG-HdrABC) from methanogenic archaea, and the transhydrogenase (NfnAB) from many Gram positive and Gram negative bacteria and from anaerobic archaea. The Bcd/EtfBC complex that catalyzes electron bifurcation from NADH to the low potential ferredoxin and to the high potential crotonyl-CoA has already been studied in some detail. The bifurcating protein most likely is EtfBC, which in each subunit (βγ) contains one FAD. In analogy to the bifurcating complex III of the mitochondrial respiratory chain and with the help of the structure of the human ETF, we propose a conformational change by which γ-FADH(-) in EtfBC approaches β-FAD to enable the bifurcating one-electron transfer. The ferredoxin reduced in one of the four electron bifurcating reactions can regenerate H(2) or NADPH, reduce CO(2) in acetogenic bacteria and methanogenic archaea, or is converted to ΔμH(+)/Na(+) by the membrane-associated enzyme complexes Rnf and Ech, whereby NADH and H(2) are recycled, respectively. The mainly bacterial Rnf complexes couple ferredoxin oxidation by NAD(+) with proton/sodium ion translocation and the more diverse energy converting [NiFe]hydrogenases (Ech) do the same, whereby NAD(+) is replaced by H(+). Many organisms also use Rnf and Ech in the reverse direction to reduce ferredoxin driven by ΔμH(+)/Na(+). Finally examples are shown, in which the four bifurcating multienzyme complexes alone or together with Rnf and Ech are integrated into energy metabolisms of nine anaerobes. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.
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Affiliation(s)
- Wolfgang Buckel
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Str. 10, 35043 Marburg, and Fachbereich Biologie, Philipps-Universität, Marburg, Germany.
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Vasileva D, Janssen H, Hönicke D, Ehrenreich A, Bahl H. Effect of iron limitation and fur gene inactivation on the transcriptional profile of the strict anaerobe Clostridium acetobutylicum. Microbiology (Reading) 2012; 158:1918-1929. [DOI: 10.1099/mic.0.056978-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Delyana Vasileva
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
| | - Holger Janssen
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
| | - Daniel Hönicke
- Lehrstuhl für Mikrobiologie, Technische Universität München, Emil-Ramann-Str. 4, D-85350, Freising, Germany
| | - Armin Ehrenreich
- Lehrstuhl für Mikrobiologie, Technische Universität München, Emil-Ramann-Str. 4, D-85350, Freising, Germany
| | - Hubert Bahl
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
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Sivagnanam K, Raghavan VGS, Shah M, Hettich RL, Verberkmoes NC, Lefsrud MG. Shotgun proteomic monitoring of Clostridium acetobutylicum during stationary phase of butanol fermentation using xylose and comparison with the exponential phase. ACTA ACUST UNITED AC 2012; 39:949-55. [DOI: 10.1007/s10295-012-1094-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 01/18/2012] [Indexed: 11/25/2022]
Abstract
Abstract
Economically viable production of solvents through acetone–butanol–ethanol (ABE) fermentation requires a detailed understanding of Clostridium acetobutylicum. This study focuses on the proteomic profiling of C. acetobutylicum ATCC 824 from the stationary phase of ABE fermentation using xylose and compares with the exponential growth by shotgun proteomics approach. Comparative proteomic analysis revealed 22.9% of the C. acetobutylicum genome and 18.6% was found to be common in both exponential and stationary phases. The proteomic profile of C. acetobutylicum changed during the ABE fermentation such that 17 proteins were significantly differentially expressed between the two phases. Specifically, the expression of five proteins namely, CAC2873, CAP0164, CAP0165, CAC3298, and CAC1742 involved in the solvent production pathway were found to be significantly lower in the stationary phase compared to the exponential growth. Similarly, the expression of fucose isomerase (CAC2610), xylulose kinase (CAC2612), and a putative uncharacterized protein (CAC2611) involved in the xylose utilization pathway were also significantly lower in the stationary phase. These findings provide an insight into the metabolic behavior of C. acetobutylicum between different phases of ABE fermentation using xylose.
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Affiliation(s)
- Kumaran Sivagnanam
- grid.14709.3b 0000000419368649 Department of Bioresource Engineering, Macdonald Campus McGill University Montreal QC Canada
| | - Vijaya G S Raghavan
- grid.14709.3b 0000000419368649 Department of Bioresource Engineering, Macdonald Campus McGill University Montreal QC Canada
| | - Manesh Shah
- grid.135519.a 0000000404462659 Chemical and Life Sciences Divisions Oak Ridge National Laboratory Oak Ridge TN USA
| | - Robert L Hettich
- grid.135519.a 0000000404462659 Chemical and Life Sciences Divisions Oak Ridge National Laboratory Oak Ridge TN USA
| | - Nathan C Verberkmoes
- grid.135519.a 0000000404462659 Chemical and Life Sciences Divisions Oak Ridge National Laboratory Oak Ridge TN USA
| | - Mark G Lefsrud
- grid.14709.3b 0000000419368649 Department of Bioresource Engineering, Macdonald Campus McGill University Montreal QC Canada
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237
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Tracy BP, Jones SW, Fast AG, Indurthi DC, Papoutsakis ET. Clostridia: the importance of their exceptional substrate and metabolite diversity for biofuel and biorefinery applications. Curr Opin Biotechnol 2012; 23:364-81. [DOI: 10.1016/j.copbio.2011.10.008] [Citation(s) in RCA: 313] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/06/2011] [Accepted: 10/20/2011] [Indexed: 12/19/2022]
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238
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Phosphoproteomic investigation of a solvent producing bacterium Clostridium acetobutylicum. Appl Microbiol Biotechnol 2012; 95:201-11. [PMID: 22627760 DOI: 10.1007/s00253-012-4156-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 05/01/2012] [Accepted: 05/04/2012] [Indexed: 10/28/2022]
Abstract
In this study, we employed TiO₂ enrichment and high accuracy liquid chromatography-mass spectrometry-mass spectrometry to identify the phosphoproteome of Clostridium acetobutyicum ATCC824 in acidogenesis and solventogenesis. As many as 82 phosphopeptides in 61 proteins, with 107 phosphorylated sites on serine, threonine, or tyrosine, were identified with high confidence. We detected 52 phosphopeptides from 44 proteins in acidogenesis and 70 phosphopeptides from 51 proteins in solventogenesis, respectively. Bioinformatic analysis revealed most of the phosphoproteins located in cytoplasm and participated in carbon metabolism. Based on comparison between the two stages, we found 27 stage-specific phosphorylated proteins (10 in acidogenesis and 17 in solventogenesis), some of which were solvent production-related enzymes and metabolic regulators, showed significantly different phosphorylated status. Further analysis indicated that protein phosphorylation could be involved in the shift of stages or in solvent production pathway directly. Comparison against several other organisms revealed the evolutionary diversity among them on phosphorylation level in spite of their high homology on protein sequence level.
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239
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Caldicellulosiruptor core and pangenomes reveal determinants for noncellulosomal thermophilic deconstruction of plant biomass. J Bacteriol 2012; 194:4015-28. [PMID: 22636774 DOI: 10.1128/jb.00266-12] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Extremely thermophilic bacteria of the genus Caldicellulosiruptor utilize carbohydrate components of plant cell walls, including cellulose and hemicellulose, facilitated by a diverse set of glycoside hydrolases (GHs). From a biofuel perspective, this capability is crucial for deconstruction of plant biomass into fermentable sugars. While all species from the genus grow on xylan and acid-pretreated switchgrass, growth on crystalline cellulose is variable. The basis for this variability was examined using microbiological, genomic, and proteomic analyses of eight globally diverse Caldicellulosiruptor species. The open Caldicellulosiruptor pangenome (4,009 open reading frames [ORFs]) encodes 106 GHs, representing 43 GH families, but only 26 GHs from 17 families are included in the core (noncellulosic) genome (1,543 ORFs). Differentiating the strongly cellulolytic Caldicellulosiruptor species from the others is a specific genomic locus that encodes multidomain cellulases from GH families 9 and 48, which are associated with cellulose-binding modules. This locus also encodes a novel adhesin associated with type IV pili, which was identified in the exoproteome bound to crystalline cellulose. Taking into account the core genomes, pangenomes, and individual genomes, the ancestral Caldicellulosiruptor was likely cellulolytic and evolved, in some cases, into species that lost the ability to degrade crystalline cellulose while maintaining the capacity to hydrolyze amorphous cellulose and hemicellulose.
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240
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Lehmann D, Radomski N, Lütke-Eversloh T. New insights into the butyric acid metabolism of Clostridium acetobutylicum. Appl Microbiol Biotechnol 2012; 96:1325-39. [PMID: 22576943 DOI: 10.1007/s00253-012-4109-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 04/13/2012] [Accepted: 04/16/2012] [Indexed: 01/17/2023]
Abstract
Biosynthesis of acetone and n-butanol is naturally restricted to the group of solventogenic clostridia with Clostridium acetobutylicum being the model organism for acetone-butanol-ethanol (ABE) fermentation. According to limited genetic tools, only a few rational metabolic engineering approaches were conducted in the past to improve the production of butanol, an advanced biofuel. In this study, a phosphotransbutyrylase-(Ptb) negative mutant, C. acetobutylicum ptb::int(87), was generated using the ClosTron methodology for targeted gene knock-out and resulted in a distinct butyrate-negative phenotype. The major end products of fermentation experiments without pH control were acetate (3.2 g/l), lactate (4.0 g/l), and butanol (3.4 g/l). The product pattern of the ptb mutant was altered to high ethanol (12.1 g/l) and butanol (8.0 g/l) titers in pH ≥ 5.0-regulated fermentations. Glucose fed-batch cultivation elevated the ethanol concentration to 32.4 g/l, yielding a more than fourfold increased alcohol to acetone ratio as compared to the wildtype. Although butyrate was never detected in cultures of C. acetobutylicum ptb::int(87), the mutant was still capable to take up butyrate when externally added during the late exponential growth phase. These findings suggest that alternative pathways of butyrate re-assimilation exist in C. acetobutylicum, supposably mediated by acetoacetyl-CoA:acyl-CoA transferase and acetoacetate decarboxylase, as well as reverse reactions of butyrate kinase and Ptb with respect to previous studies.
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Affiliation(s)
- Dörte Lehmann
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany
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241
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Gao X, Zhao H, Zhang G, He K, Jin Y. Genome shuffling of Clostridium acetobutylicum CICC 8012 for improved production of acetone-butanol-ethanol (ABE). Curr Microbiol 2012; 65:128-32. [PMID: 22562601 DOI: 10.1007/s00284-012-0134-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/17/2012] [Indexed: 10/28/2022]
Abstract
Genome shuffling was applied to increase ABE production of the strict anaerobe C. acetobutylicum CICC 8012. By using physical and chemical mutagenesis, strains with superior streptomycin sulfate, 2-deoxy-D-glucose and butanol tolerance levels were isolated. These strains were used for genome shuffling. The best performing strain F2-GA was screened after two rounds of genome shuffling. With 55 g glucose/l as carbon source, F2-GA produced 22.21 g ABE/l in 72 h and ABE yield reached 0.42 g/g which was about 34.53 % improvement compared to the wild type. Fermentation parameters and gene expression of several key enzymes in ABE metabolic pathways were varied significantly between F2-GA and the wild type. These results demonstrated the potential use of genome shuffling to microbial breeding which were difficult to deal with traditional methods.
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Affiliation(s)
- Xiaofeng Gao
- Chengdu Institute of Biology, Chinese Academy of Sciences, China.
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242
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Saad NY, Schiel B, Brayé M, Heap JT, Minton NP, Dürre P, Becker HD. Riboswitch (T-box)-mediated control of tRNA-dependent amidation in Clostridium acetobutylicum rationalizes gene and pathway redundancy for asparagine and asparaginyl-trnaasn synthesis. J Biol Chem 2012; 287:20382-94. [PMID: 22505715 DOI: 10.1074/jbc.m111.332304] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Analysis of the Gram-positive Clostridium acetobutylicum genome reveals an inexplicable level of redundancy for the genes putatively involved in asparagine (Asn) and Asn-tRNA(Asn) synthesis. Besides a duplicated set of gatCAB tRNA-dependent amidotransferase genes, there is a triplication of aspartyl-tRNA synthetase genes and a duplication of asparagine synthetase B genes. This genomic landscape leads to the suspicion of the incoherent simultaneous use of the direct and indirect pathways of Asn and Asn-tRNA(Asn) formation. Through a combination of biochemical and genetic approaches, we show that C. acetobutylicum forms Asn and Asn-tRNA(Asn) by tRNA-dependent amidation. We demonstrate that an entire transamidation pathway composed of aspartyl-tRNA synthetase and one set of GatCAB genes is organized as an operon under the control of a tRNA(Asn)-dependent T-box riboswitch. Finally, our results suggest that this exceptional gene redundancy might be interconnected to control tRNA-dependent Asn synthesis, which in turn might be involved in controlling the metabolic switch from acidogenesis to solventogenesis in C. acetobutylicum.
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Affiliation(s)
- Nizar Y Saad
- Unité Mixte de Recherche "Génétique Moléculaire, Génomique, Microbiologie," CNRS, Université de Strasbourg, 21 rue René Descartes, 67084 Strasbourg, France
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243
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Schwarz KM, Kuit W, Grimmler C, Ehrenreich A, Kengen SWM. A transcriptional study of acidogenic chemostat cells of Clostridium acetobutylicum--cellular behavior in adaptation to n-butanol. J Biotechnol 2012; 161:366-77. [PMID: 22484128 DOI: 10.1016/j.jbiotec.2012.03.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/05/2012] [Accepted: 03/21/2012] [Indexed: 12/18/2022]
Abstract
To gain more insight into the butanol stress response of Clostridium acetobutylicum the transcriptional response of a steady state acidogenic culture to different levels of n-butanol (0.25-1%) was investigated. No effect was observed on the fermentation pattern and expression of typical solvent genes (aad, ctfA/B, adc, bdhA/B, ptb, buk). Elevated levels of butanol mainly affected class I heat-shock genes (hrcA, grpE, dnaK, dnaJ, groES, groEL, hsp90), which were upregulated in a dose- and time-dependent manner, and genes encoding proteins involved in the membrane composition (fab and fad or glycerophospholipid related genes) and various ABC-transporters of unknown specificity. Interestingly, fab and fad genes were embedded in a large, entirely repressed cluster (CAC1988-CAC2019), which inter alia encoded an iron-specific ABC-transporter and molybdenum-cofactor synthesis proteins. Of the glycerophospholipid metabolism, the glycerol-3-phosphate dehydrogenase (glpA) gene was highly upregulated, whereas a glycerophosphodiester ABC-transporter (ugpAEBC) and a phosphodiesterase (ugpC) were repressed. On the megaplasmid, only a few genes showed differential expression, e.g. a rare lipoprotein (CAP0058, repressed) and a membrane protein (CAP0102, upregulated) gene. Observed transcriptional responses suggest that C. acetobutylicum reacts to butanol stress by induction of the general stress response and changing its cell envelope and transporter composition, but leaving the central catabolism unaffected.
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Affiliation(s)
- Katrin M Schwarz
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands
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244
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Wang Y, Li X, Mao Y, Blaschek HP. Genome-wide dynamic transcriptional profiling in Clostridium beijerinckii NCIMB 8052 using single-nucleotide resolution RNA-Seq. BMC Genomics 2012; 13:102. [PMID: 22433311 PMCID: PMC3395874 DOI: 10.1186/1471-2164-13-102] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 03/20/2012] [Indexed: 12/31/2022] Open
Abstract
Background Clostridium beijerinckii is a prominent solvent-producing microbe that has great potential for biofuel and chemical industries. Although transcriptional analysis is essential to understand gene functions and regulation and thus elucidate proper strategies for further strain improvement, limited information is available on the genome-wide transcriptional analysis for C. beijerinckii. Results The genome-wide transcriptional dynamics of C. beijerinckii NCIMB 8052 over a batch fermentation process was investigated using high-throughput RNA-Seq technology. The gene expression profiles indicated that the glycolysis genes were highly expressed throughout the fermentation, with comparatively more active expression during acidogenesis phase. The expression of acid formation genes was down-regulated at the onset of solvent formation, in accordance with the metabolic pathway shift from acidogenesis to solventogenesis. The acetone formation gene (adc), as a part of the sol operon, exhibited highly-coordinated expression with the other sol genes. Out of the > 20 genes encoding alcohol dehydrogenase in C. beijerinckii, Cbei_1722 and Cbei_2181 were highly up-regulated at the onset of solventogenesis, corresponding to their key roles in primary alcohol production. Most sporulation genes in C. beijerinckii 8052 demonstrated similar temporal expression patterns to those observed in B. subtilis and C. acetobutylicum, while sporulation sigma factor genes sigE and sigG exhibited accelerated and stronger expression in C. beijerinckii 8052, which is consistent with the more rapid forespore and endspore development in this strain. Global expression patterns for specific gene functional classes were examined using self-organizing map analysis. The genes associated with specific functional classes demonstrated global expression profiles corresponding to the cell physiological variation and metabolic pathway switch. Conclusions The results from this work provided insights for further C. beijerinckii strain improvement employing system biology-based strategies and metabolic engineering approaches.
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Affiliation(s)
- Yi Wang
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 61801, USA
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245
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Zakrzewski M, Goesmann A, Jaenicke S, Jünemann S, Eikmeyer F, Szczepanowski R, Al-Soud WA, Sørensen S, Pühler A, Schlüter A. Profiling of the metabolically active community from a production-scale biogas plant by means of high-throughput metatranscriptome sequencing. J Biotechnol 2012; 158:248-58. [PMID: 22342600 DOI: 10.1016/j.jbiotec.2012.01.020] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 01/10/2012] [Accepted: 01/13/2012] [Indexed: 02/02/2023]
Abstract
Structural composition and gene content of a biogas-producing microbial community from a production-scale biogas plant fed with renewable primary products was recently analyzed by means of a metagenome sequencing approach. To determine the transcriptionally active part of the same biogas community and to identify key transcripts for the biogas production process, the metatranscriptome of the microorganisms was sequenced for the first time. The metatranscriptome sequence dataset generated on the Genome Sequencer FLX platform is represented by 484,920 sequence reads. Taxonomic profiling of the active part of the community by classification of 16S ribosomal sequence tags revealed that members of the Euryarchaeota and Firmicutes account for the dominant phyla. Only smaller fractions of the 16S ribosomal sequence tags were assigned to the phyla Bacteroidetes, Actinobacteria and Synergistetes. Among the mRNA-derived sequence tags from the metatranscriptome dataset, transcripts encoding enzymes involved in substrate hydrolysis, acidogenesis, acetate formation and methanogenesis could be identified. Transcripts for enzymes functioning in methanogenesis are among the most abundant mRNA tags indicating that the corresponding pathway is very active in the methanogenic sub-community. As a frame of reference for evaluation of metatranscriptome sequence data, the 16S rDNA-based taxonomic profile of the community was analyzed by means of high-throughput 16S rDNA amplicon sequencing. Processing of the obtained amplicon reads resulted in 18,598 high-quality 16S rDNA sequences covering the V3-V4 hypervariable region of the 16S rRNA gene. Comparison of the taxonomic profiles deduced from 16S rDNA amplicon sequences and the metatranscriptome dataset indicates a high transcriptional activity of archaeal species. Overall, it was shown that the most abundant species dominating the community also contributed the majority of the transcripts. In the future, key transcripts for the biogas production process will provide valuable markers for evaluation of the performance of biogas-producing microbial communities with the objective to optimize the biotechnology of this process.
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Affiliation(s)
- Martha Zakrzewski
- Computational Genomics, Center for Biotechnology-CeBiTec, Bielefeld University, Bielefeld, Germany
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246
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Complete genome sequences of rat and mouse segmented filamentous bacteria, a potent inducer of th17 cell differentiation. Cell Host Microbe 2012; 10:273-84. [PMID: 21925114 DOI: 10.1016/j.chom.2011.08.007] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/04/2011] [Accepted: 08/17/2011] [Indexed: 12/12/2022]
Abstract
Segmented filamentous bacteria (SFB) are noncultivable commensals inhabiting the gut of various vertebrate species and have been shown to induce Th17 cells in mice. We present the complete genome sequences of both rat and mouse SFB isolated from SFB-monocolonized hosts. The rat and mouse SFB genomes each harbor a single circular chromosome of 1.52 and 1.59 Mb encoding 1346 and 1420 protein-coding genes, respectively. The overall nucleotide identity between the two genomes is 86%, and the substitution rate was estimated to be similar to that of the free-living E. coli. SFB genomes encode typical genes for anaerobic fermentation and spore and flagella formation, but lack most of the amino acid biosynthesis enzymes, reminiscent of pathogenic Clostridia, exhibiting large dependency on the host. However, SFB lack most of the clostridial virulence-related genes. Comparative analysis with clostridial genomes suggested possible mechanisms for host responses and specific adaptations in the intestine.
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247
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Stuart GW, Berry MW. A Comprehensive Whole Genome Bacterial Phylogeny Using Correlated Peptide Motifs Defined in a High Dimensional Vector Space. J Bioinform Comput Biol 2012; 1:475-93. [PMID: 15290766 DOI: 10.1142/s0219720003000265] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2003] [Revised: 04/28/2003] [Accepted: 04/29/2003] [Indexed: 11/18/2022]
Abstract
As whole genome sequences continue to expand in number and complexity, effective methods for comparing and categorizing both genes and species represented within extremely large datasets are required. Methods introduced to date have generally utilized incomplete and likely insufficient subsets of the available data. We have developed an accurate and efficient method for producing robust gene and species phylogenies using very large whole genome protein datasets. This method relies on multidimensional protein vector definitions supplied by the singular value decomposition (SVD) of a large sparse data matrix in which each protein is uniquely represented as a vector of overlapping tetrapeptide frequencies. Quantitative pairwise estimates of species similarity were obtained by summing the protein vectors to form species vectors, then determining the cosines of the angles between species vectors. Evolutionary trees produced using this method confirmed many accepted prokaryotic relationships. However, several unconventional relationships were also noted. In addition, we demonstrate that many of the SVD-derived right basis vectors represent particular conserved protein families, while many of the corresponding left basis vectors describe conserved motifs within these families as sets of correlated peptides (copeps). This analysis represents the most detailed simultaneous comparison of prokaryotic genes and species available to date.
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Affiliation(s)
- Gary W Stuart
- Department of Life Sciences, Indiana State University, Terre Haute, IN 47809, USA.
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248
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Hönicke D, Janssen H, Grimmler C, Ehrenreich A, Lütke-Eversloh T. Global transcriptional changes of Clostridium acetobutylicum cultures with increased butanol:acetone ratios. N Biotechnol 2012; 29:485-93. [PMID: 22285530 DOI: 10.1016/j.nbt.2012.01.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/12/2012] [Accepted: 01/12/2012] [Indexed: 10/14/2022]
Abstract
Artificial electron carriers have been widely used to shift the solvent ratio toward butanol in acetone-butanol-ethanol (ABE) fermentation of solventogenic clostridia according to decreased hydrogen production. In this study, first insights on the molecular level were gained to explore the effect of methyl viologen addition to cultures of Clostridium acetobutylicum. Employing batch fermentation in mineral salts medium, the butanol:acetone ratio was successively increased from 2.3 to 12.4 on a 100-ml scale in serum bottles and from 1.4 to 16.5 on a 1300-ml scale in bioreactors, respectively. The latter cultures were used for DNA microarray analyses to provide new information on the transcriptional changes referring to methyl viologen exposure and thus, exhibit gene expression patterns according to the manipulation of the cellular redox balance. Methyl viologen-exposed cultures revealed lower expression levels of the sol operon (CAP0162-0164) and the adjacent adc gene (CAP0165) responsible for solvent formation as well as iron and sulfate transporters and the CAC0105-encoded ferredoxin. On the contrary, genes for riboflavin biosynthesis, for the butyrate/butanol metabolic pathway and genes coding for sugar transport systems were induced. Interestingly, the adhE2-encoded bifunctional NADH-dependent aldhehyde/alcohol-dehydrogenase (CAP0035) was upregulated up to more than 100-fold expression levels as compared to the control culture without methyl viologen addition. The data presented here indicate a transcriptional regulation for decreased acetone biosynthesis and the redox-dependent substitution of adhE1 (CAP0162) by adhE2.
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Affiliation(s)
- Daniel Hönicke
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Germany
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249
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Lehmann D, Hönicke D, Ehrenreich A, Schmidt M, Weuster-Botz D, Bahl H, Lütke-Eversloh T. Modifying the product pattern of Clostridium acetobutylicum. Appl Microbiol Biotechnol 2012; 94:743-54. [DOI: 10.1007/s00253-011-3852-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 12/19/2011] [Accepted: 12/21/2011] [Indexed: 01/20/2023]
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250
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Dong H, Tao W, Zhang Y, Li Y. Development of an anhydrotetracycline-inducible gene expression system for solvent-producing Clostridium acetobutylicum: A useful tool for strain engineering. Metab Eng 2012; 14:59-67. [DOI: 10.1016/j.ymben.2011.10.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 09/23/2011] [Accepted: 10/21/2011] [Indexed: 12/14/2022]
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