51
|
Liu D, Chen Y, Ding F, Guo T, Xie J, Zhuang W, Niu H, Shi X, Zhu C, Ying H. Simultaneous production of butanol and acetoin by metabolically engineered Clostridium acetobutylicum. Metab Eng 2015; 27:107-114. [DOI: 10.1016/j.ymben.2014.11.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 09/13/2014] [Accepted: 11/12/2014] [Indexed: 12/26/2022]
|
52
|
Di Pietrantonio K, Coccia F, Tonucci L, d'Alessandro N, Bressan M. Hydrogenation of allyl alcohols catalyzed by aqueous palladium and platinum nanoparticles. RSC Adv 2015. [DOI: 10.1039/c5ra13840j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hydrogenations of allyl alcohols in aqueous media, at room temperature and pressure, were performed in presence of Pd or Pt lignin nanoparticles as catalysts to obtain saturated alcohols.
Collapse
Affiliation(s)
| | - Francesca Coccia
- Department of Engineering and Geology
- G. d'Annunzio University of Chieti-Pescara
- Italy
| | - Lucia Tonucci
- Department of Philosophical
- Educational and Economic Sciences
- G. d'Annunzio University of Chieti-Pescara
- Italy
| | - Nicola d'Alessandro
- Department of Engineering and Geology
- G. d'Annunzio University of Chieti-Pescara
- Italy
| | - Mario Bressan
- Department of Engineering and Geology
- G. d'Annunzio University of Chieti-Pescara
- Italy
| |
Collapse
|
53
|
Engineering Clostridium acetobutylicum with a histidine kinase knockout for enhanced n-butanol tolerance and production. Appl Microbiol Biotechnol 2014; 99:1011-22. [DOI: 10.1007/s00253-014-6249-7] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 01/07/2023]
|
54
|
Wen Z, Wu M, Lin Y, Yang L, Lin J, Cen P. A novel strategy for sequential co-culture of Clostridium thermocellum and Clostridium beijerinckii to produce solvents from alkali extracted corn cobs. Process Biochem 2014. [DOI: 10.1016/j.procbio.2014.07.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
55
|
Utilization of economical substrate-derived carbohydrates by solventogenic clostridia: pathway dissection, regulation and engineering. Curr Opin Biotechnol 2014; 29:124-31. [DOI: 10.1016/j.copbio.2014.04.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/21/2014] [Accepted: 04/02/2014] [Indexed: 01/15/2023]
|
56
|
Schweitzer D, Mullen CA, Boateng AA, Snell KD. Biobased n-Butanol Prepared from Poly-3-hydroxybutyrate: Optimization of the Reduction of n-Butyl Crotonate to n-Butanol. Org Process Res Dev 2014. [DOI: 10.1021/op500156b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Dirk Schweitzer
- Metabolix, 21 Erie St., Cambridge, Massachusetts 02139, United States
| | - Charles A. Mullen
- Eastern
Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 E. Mermaid Lane, Wyndmoor, Pennsylvania 19038, United States
| | - Akwasi A. Boateng
- Eastern
Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 E. Mermaid Lane, Wyndmoor, Pennsylvania 19038, United States
| | - Kristi D. Snell
- Metabolix, 21 Erie St., Cambridge, Massachusetts 02139, United States
| |
Collapse
|
57
|
Wen Z, Wu M, Lin Y, Yang L, Lin J, Cen P. Artificial symbiosis for acetone-butanol-ethanol (ABE) fermentation from alkali extracted deshelled corn cobs by co-culture of Clostridium beijerinckii and Clostridium cellulovorans. Microb Cell Fact 2014; 13:92. [PMID: 25023325 PMCID: PMC4223388 DOI: 10.1186/s12934-014-0092-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 06/17/2014] [Indexed: 02/02/2023] Open
Abstract
Background Butanol is an industrial commodity and also considered to be a more promising gasoline substitute compared to ethanol. Renewed attention has been paid to solvents (acetone, butanol and ethanol) production from the renewable and inexpensive substrates, for example, lignocellulose, on account of the depletion of oil resources, increasing gasoline prices and deteriorating environment. Limited to current tools for genetic manipulation, it is difficult to develop a genetically engineered microorganism with combined ability of lignocellulose utilization and solvents production. Mixed culture of cellulolytic microorganisms and solventogenic bacteria provides a more convenient and feasible approach for ABE fermentation due to the potential for synergistic utilization of the metabolic pathways of two organisms. But few bacteria pairs succeeded in producing biobutanol of high titer or high productivity without adding butyrate. The aim of this work was to use Clostridium cellulovorans 743B to saccharify lignocellulose and produce butyric acid, instead of adding cellulase and butyric acid to the medium, so that the soluble sugars and butyric acid generated can be subsequently utilized by Clostridium beijerinckii NCIMB 8052 to produce butanol in one pot reaction. Results A stable artificial symbiotic system was constructed by co-culturing a celluloytic, anaerobic, butyrate-producing mesophile (C. cellulovorans 743B) and a non-celluloytic, solventogenic bacterium (C. beijerinckii NCIMB 8052) to produce solvents by consolidated bioprocessing (CBP) with alkali extracted deshelled corn cobs (AECC), a low-cost renewable feedstock, as the sole carbon source. Under optimized conditions, the co-culture degraded 68.6 g/L AECC and produced 11.8 g/L solvents (2.64 g/L acetone, 8.30 g/L butanol and 0.87 g/L ethanol) in less than 80 h. Besides, a real-time PCR assay based on the 16S rRNA gene sequence was performed to study the dynamics of the abundance of each strain during the co-culturing process, which figured out the roles of each strain at different periods in the symbiosis. Conclusion Our work illustrated the great potential of artificial symbiosis in biofuel production from lignocellulosic biomass by CBP. The dynamics of the abundance of C. beijerinckii and C. cellulovorans revealed mechanisms of cooperation and competition between the two strains during the co-culture process.
Collapse
|
58
|
Abstract
Abstract
Recent studies have shown that butanol is a potential gasoline replacement that can also be blended in significant quantities with conventional diesel fuel. However, biotechnological production of butanol has some challenges such as low butanol titer, high cost feedstocks and product inhibition. The present work reviewed the technical and economic feasibility of the main technologies available to produce biobutanol. The latest studies integrating continuous fermentation processes with efficient product recovery and the use of mathematical models as tools for process scale-up, optimization and control are presented.
Collapse
|
59
|
Lütke-Eversloh T. Application of new metabolic engineering tools for Clostridium acetobutylicum. Appl Microbiol Biotechnol 2014; 98:5823-37. [DOI: 10.1007/s00253-014-5785-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 01/30/2023]
|
60
|
Jang YS, Han MJ, Lee J, Im JA, Lee YH, Papoutsakis ET, Bennett G, Lee SY. Proteomic analyses of the phase transition from acidogenesis to solventogenesis using solventogenic and non-solventogenic Clostridium acetobutylicum strains. Appl Microbiol Biotechnol 2014; 98:5105-15. [PMID: 24743985 DOI: 10.1007/s00253-014-5738-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 03/27/2014] [Accepted: 03/29/2014] [Indexed: 01/07/2023]
Abstract
The fermentation carried out by the solvent-producing bacterium, Clostridium acetobutylicum, is characterized by two distinct phases: acidogenic and solventogenic phases. Understanding the cellular physiological changes occurring during the phase transition in clostridial fermentation is important for the enhanced production of solvents. To identify protein changes upon entry to stationary phase where solvents are typically produced, we herein analyzed the proteomic profiles of the parental wild type C. acetobutylicum strains, ATCC 824, the non-solventogenic strain, M5 that has lost the solventogenic megaplasmid pSOL1, and the synthetic simplified alcohol forming strain, M5 (pIMP1E1AB) expressing plasmid-based CoA-transferase (CtfAB) and aldehyde/alcohol dehydrogenase (AdhE1). A total of 68 protein spots, corresponding to 56 unique proteins, were unambiguously identified as being differentially present after the phase transitions in the three C. acetobutylicum strains. In addition to changes in proteins known to be involved in solventogenesis (AdhE1 and CtfB), we identified significant alterations in enzymes involved in sugar transport and metabolism, fermentative pathway, heat shock proteins, translation, and amino acid biosynthesis upon entry into the stationary phase. Of these, four increased proteins (AdhE1, CAC0233, CtfB and phosphocarrier protein HPr) and six decreased proteins (butyrate kinase, ferredoxin:pyruvate oxidoreductase, phenylalanyl-tRNA synthetase, adenylosuccinate synthase, pyruvate kinase and valyl-tRNA synthetase) showed similar patterns in the two strains capable of butanol formation. Interestingly, significant changes of several proteins by post-translational modifications were observed in the solventogenic phase. The proteomic data from this study will improve our understanding on how cell physiology is affected through protein levels patterns in clostridia.
Collapse
Affiliation(s)
- Yu-Sin Jang
- Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 plus program), BioProcess Engineering Research Center, Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701, South Korea
| | | | | | | | | | | | | | | |
Collapse
|
61
|
Jin L, Zhang H, Chen L, Yang C, Yang S, Jiang W, Gu Y. Combined overexpression of genes involved in pentose phosphate pathway enables enhanced d-xylose utilization by Clostridium acetobutylicum. J Biotechnol 2014; 173:7-9. [DOI: 10.1016/j.jbiotec.2014.01.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/24/2013] [Accepted: 01/02/2014] [Indexed: 12/01/2022]
|
62
|
Falano T, Jeswani HK, Azapagic A. Assessing the environmental sustainability of ethanol from integrated biorefineries. Biotechnol J 2014; 9:753-65. [PMID: 24478110 PMCID: PMC4674963 DOI: 10.1002/biot.201300246] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/19/2013] [Accepted: 01/24/2014] [Indexed: 12/12/2022]
Abstract
This paper considers the life cycle environmental sustainability of ethanol produced in integrated biorefineries together with chemicals and energy. Four types of second-generation feedstocks are considered: wheat straw, forest residue, poplar, and miscanthus. Seven out of 11 environmental impacts from ethanol are negative, including greenhouse gas (GHG) emissions, when the system is credited for the co-products, indicating environmental savings. Ethanol from poplar is the best and straw the worst option for most impacts. Land use change from forest to miscanthus increases the GHG emissions several-fold. For poplar, the effect is opposite: converting grassland to forest reduces the emissions by three-fold. Compared to fossil and first-generation ethanol, ethanol from integrated biorefineries is more sustainable for most impacts, with the exception of wheat straw. Pure ethanol saves up to 87% of GHG emissions compared to petrol per MJ of fuel. However, for the current 5% ethanol–petrol blends, the savings are much smaller (<3%). Therefore, unless much higher blends become widespread, the contribution of ethanol from integrated biorefineries to the reduction of GHG emissions will be insignificant. Yet, higher ethanol blends would lead to an increase in some impacts, notably terrestrial and freshwater toxicity as well as eutrophication for some feedstocks.
Collapse
Affiliation(s)
- Temitope Falano
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
| | | | | |
Collapse
|
63
|
Singh V, Mani I, Chaudhary DK, Dhar PK. Metabolic engineering of biosynthetic pathway for production of renewable biofuels. Appl Biochem Biotechnol 2013; 172:1158-71. [PMID: 24197521 DOI: 10.1007/s12010-013-0606-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 10/23/2013] [Indexed: 12/12/2022]
Abstract
Metabolic engineering is an important area of research that involves editing genetic networks to overproduce a certain substance by the cells. Using a combination of genetic, metabolic, and modeling methods, useful substances have been synthesized in the past at industrial scale and in a cost-effective manner. Currently, metabolic engineering is being used to produce sufficient, economical, and eco-friendly biofuels. In the recent past, a number of efforts have been made towards engineering biosynthetic pathways for large scale and efficient production of biofuels from biomass. Given the adoption of metabolic engineering approaches by the biofuel industry, this paper reviews various approaches towards the production and enhancement of renewable biofuels such as ethanol, butanol, isopropanol, hydrogen, and biodiesel. We have also identified specific areas where more work needs to be done in the future.
Collapse
Affiliation(s)
- Vijai Singh
- Department of Biotechnology, Invertis University, Bareilly-Lucknow National Highway 24, Bareilly, 243123, India,
| | | | | | | |
Collapse
|
64
|
Lu C, Dong J, Yang ST. Butanol production from wood pulping hydrolysate in an integrated fermentation-gas stripping process. BIORESOURCE TECHNOLOGY 2013; 143:467-75. [PMID: 23827441 DOI: 10.1016/j.biortech.2013.06.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/02/2013] [Accepted: 06/04/2013] [Indexed: 05/05/2023]
Abstract
Wood pulping hydrolysate (WPH) containing mainly xylose and glucose as a potential substrate for acetone-butanol-ethanol (ABE) fermentation was studied. Due to the inhibitors present in the hydrolysate, several dilution levels and detoxification treatments, including overliming, activated charcoal adsorption, and resin adsorption, were evaluated for their effectiveness in relieving the inhibition on fermentation. Detoxification using resin and evaporation was found to be the most effective method in reducing the toxicity of WPH. ABE production in batch fermentation by Clostridium beijerinckii increased 68%, from 6.73 g/L in the non-treated and non-diluted WPH to 11.35 g/L in the resin treated WPH. With gas stripping for in situ product removal, ABE production from WPH increased to 17.73 g/L, demonstrating that gas stripping was effective in alleviating butanol toxicity by selectively separating butanol from the fermentation broth, which greatly improved solvents production and sugar conversion in the fermentation.
Collapse
Affiliation(s)
- Congcong Lu
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W. 19th Ave., Columbus, OH 43210, USA
| | | | | |
Collapse
|
65
|
Li Z, Xiao H, Jiang W, Jiang Y, Yang S. Improvement of solvent production from xylose mother liquor by engineering the xylose metabolic pathway in Clostridium acetobutylicum EA 2018. Appl Biochem Biotechnol 2013; 171:555-68. [PMID: 23949683 DOI: 10.1007/s12010-013-0414-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 07/22/2013] [Indexed: 12/15/2022]
Abstract
Xylose mother liquor (XML) is a by-product of xylose production through acid hydrolysis from corncobs, which can be used potentially for alternative fermentation feedstock. Sixteen Clostridia including 13 wild-type, 1 industrial strain, and 2 genetically engineered strains were screened in XML, among which the industrial strain Clostridium acetobutylicum EA 2018 showed the highest titer of solvents (12.7 g/L) among non-genetic populations, whereas only 40% of the xylose was consumed. An engineered strain (2018glcG-TBA) obtained by combination of glcG disruption and expression of the D-xylose proton-symporter, D-xylose isomerase, and xylulokinase was able to completely utilize glucose and L-arabinose, and 88% xylose in XML. The 2018glcG-TBA produced total solvents up to 21 g/L with a 50% enhancement of total solvent yield (0.33 g/g sugar) compared to that of EA 2018 (0.21 g/g sugar) in XML. This XML-based acetone-butanol-ethanol fermentation using recombinant 2018glcG-TBA was estimated to be economically promising for future production of solvents.
Collapse
Affiliation(s)
- Zhilin Li
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | | | | | | | | |
Collapse
|
66
|
Jang YS, Malaviya A, Lee J, Im JA, Lee SY, Lee J, Eom MH, Cho JH, Seung DY. Metabolic engineering of Clostridium acetobutylicum for the enhanced production of isopropanol-butanol-ethanol fuel mixture. Biotechnol Prog 2013; 29:1083-8. [PMID: 23606675 DOI: 10.1002/btpr.1733] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/16/2013] [Indexed: 01/15/2023]
Abstract
Butanol is considered as a superior biofuel, which is conventionally produced by clostridial acetone-butanol-ethanol (ABE) fermentation. Among ABE, only butanol and ethanol can be used as fuel alternatives. Coproduction of acetone thus causes lower yield of fuel alcohols. Thus, this study aimed at developing an improved Clostridium acetobutylicum strain possessing enhanced fuel alcohol production capability. For this, we previously developed a hyper ABE producing BKM19 strain was further engineered to convert acetone into isopropanol. The BKM19 strain was transformed with the plasmid pIPA100 containing the sadh (primary/secondary alcohol dehydrogenase) and hydG (putative electron transfer protein) genes from the Clostridium beijerinckii NRRL B593 cloned under the control of the thiolase promoter. The resulting BKM19 (pIPA100) strain produced 27.9 g/l isopropanol-butanol-ethanol (IBE) as a fuel alcohols with negligible amount of acetone (0.4 g/l) from 97.8 g/l glucose in lab-scale (2 l) batch fermentation. Thus, this metabolically engineered strain was able to produce 99% of total solvent produced as fuel alcohols. The scalability and stability of BKM19 (pIPA100) were evaluated at 200 l pilot-scale fermentation, which showed that the fuel alcohol yield could be improved to 0.37 g/g as compared to 0.29 g/g obtained at lab-scale fermentation, while attaining a similar titer. To the best of our knowledge, this is the highest titer of IBE achieved and the first report on the large scale fermentation of C. acetobutylicum for IBE production.
Collapse
Affiliation(s)
- Yu-Sin Jang
- Dept. of Chemical and Biomolecular Engineering (BK21 Program), Metabolic and Biomolecular Engineering National Research Laboratory, BioProcess Engineering Research Center, KAIST, Daejeon, 305-701, Republic of Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
67
|
Genome Sequence of the Butanol Hyperproducer Clostridium saccharoperbutylacetonicum N1-4. GENOME ANNOUNCEMENTS 2013; 1:e0007013. [PMID: 23516201 PMCID: PMC3593318 DOI: 10.1128/genomea.00070-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Clostridium saccharoperbutylacetonicum is one of the most important acetone-butanol-ethanol (ABE)-generating industrial microorganisms and one of the few bacteria containing choline in its cell wall. Here, we report the draft genome sequence of C. saccharoperbutylacetonicum strain N1-4 (6.6 Mbp; G+C content, 29.4%) and the findings obtained from the annotation of the genome.
Collapse
|
68
|
Effects of nutritional enrichment on the production of acetone-butanol-ethanol (ABE) by Clostridium acetobutylicum. J Microbiol 2012; 50:1063-6. [DOI: 10.1007/s12275-012-2373-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
|
69
|
Tian X, Chen L, Wang J, Qiao J, Zhang W. Quantitative proteomics reveals dynamic responses of Synechocystis sp. PCC 6803 to next-generation biofuel butanol. J Proteomics 2012; 78:326-45. [PMID: 23079071 DOI: 10.1016/j.jprot.2012.10.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 10/01/2012] [Accepted: 10/04/2012] [Indexed: 01/04/2023]
Abstract
Butanol is a promising biofuel, and recent metabolic engineering efforts have demonstrated the use of photosynthetic cyanobacterial hosts for its production. However, cyanobacteria have very low tolerance to butanol, limiting the economic viability of butanol production from these renewable producing systems. The existing knowledge of molecular mechanism involved in butanol tolerance in cyanobacteria is very limited. To build a foundation necessary to engineer robust butanol-producing cyanobacterial hosts, in this study, the responses of Synechocystis PCC 6803 to butanol were investigated using a quantitative proteomics approach with iTRAQ - LC-MS/MS technologies. The resulting high-quality dataset consisted of 25,347 peptides corresponding to 1452 unique proteins, a coverage of approximately 40% of the predicted proteins in Synechocystis. Comparative quantification of protein abundances led to the identification of 303 differentially regulated proteins by butanol. Annotation and GO term enrichment analysis showed that multiple biological processes were regulated, suggesting that Synechocystis probably employed multiple and synergistic resistance mechanisms in dealing with butanol stress. Notably, the analysis revealed the induction of heat-shock protein and transporters, along with modification of cell membrane and envelope were the major protection mechanisms against butanol. A conceptual cellular model of Synechocystis PCC 6803 responses to butanol stress was constructed to illustrate the putative molecular mechanisms employed to defend against butanol stress.
Collapse
Affiliation(s)
- Xiaoxu Tian
- School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, PR China
| | | | | | | | | |
Collapse
|
70
|
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.
Collapse
|
71
|
Lin X, Wu J, Jin X, Fan J, Li R, Wen Q, Qian W, Liu D, Chen X, Chen Y, Xie J, Bai J, Ying H. Selective separation of biobutanol from acetone-butanol-ethanol fermentation broth by means of sorption methodology based on a novel macroporous resin. Biotechnol Prog 2012; 28:962-72. [DOI: 10.1002/btpr.1553] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 03/26/2012] [Indexed: 12/12/2022]
|
72
|
Xiao H, Li Z, Jiang Y, Yang Y, Jiang W, Gu Y, Yang S. Metabolic engineering of D-xylose pathway in Clostridium beijerinckii to optimize solvent production from xylose mother liquid. Metab Eng 2012; 14:569-78. [PMID: 22677452 DOI: 10.1016/j.ymben.2012.05.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 04/29/2012] [Accepted: 05/22/2012] [Indexed: 11/18/2022]
Abstract
Clostridium beijerinckii is an attractive butanol-producing microbe for its advantage in co-fermenting hexose and pentose sugars. However, this Clostridium strain exhibits undesired efficiency in utilizing D-xylose, one of the major building blocks contained in lignocellulosic materials. Here, we reported a useful metabolic engineering strategy to improve D-xylose consumption by C. beijerinckii. Gene cbei2385, encoding a putative D-xylose repressor XylR, was first disrupted in the C. beijerinckii NCIMB 8052, resulting in a significant increase in D-xylose consumption. A D-xylose proton-symporter (encoded by gene cbei0109) was identified and then overexpressed to further optimize D-xylose utilization, yielding an engineered strain 8052xylR-xylT(ptb) (xylR inactivation plus xylT overexpression driven by ptb promoter). We investigated the strain 8052xylR-xylT(ptb) in fermenting xylose mother liquid, an abundant by-product from industrial-scale xylose preparation from corncob and rich in D-xylose, finally achieving a 35% higher Acetone, Butanol and Ethanol (ABE) solvent titer (16.91 g/L) and a 38% higher yield (0.29 g/g) over those of the wild-type strain. The strategy used in this study enables C. beijerinckii more suitable for butanol production from lignocellulosic materials.
Collapse
Affiliation(s)
- Han Xiao
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | | | | | | | | | | | | |
Collapse
|
73
|
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.
Collapse
Affiliation(s)
- Dörte Lehmann
- Abteilung Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany
| | | | | |
Collapse
|
74
|
Zhong JJ, Lee SY. Editorial: Biotechnology Journal shines the spotlight on ACB-2011. Biotechnol J 2011; 6:1298-9. [DOI: 10.1002/biot.201100445] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|