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Baldassare MA, Bhattacharjee D, Coles JD, Nelson S, McCollum CA, Seekatz AM. Butyrate enhances Clostridioides difficile sporulation in vitro. J Bacteriol 2023; 205:e0013823. [PMID: 37655912 PMCID: PMC10521354 DOI: 10.1128/jb.00138-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/11/2023] [Indexed: 09/02/2023] Open
Abstract
Short-chain fatty acids (SCFAs) are products of bacterial fermentation that help maintain important gut functions such as maintenance of the intestinal barrier, cell signaling, and immune homeostasis. The main SCFAs acetate, propionate, and butyrate have demonstrated beneficial effects for the host, including its importance in alleviating infections caused by pathogens such as Clostridioides difficile. Despite the potential role of SCFAs in mitigating C. difficile infection, their direct effect on C. difficile remains unclear. Through a set of in vitro experiments, we investigated how SCFAs influence C. difficile growth, sporulation, and toxin production. Similar to previous studies, we observed that butyrate decreased growth of C. difficile strain 630 in a dose-dependent manner. The presence of butyrate also increased C. difficile sporulation, with minimal increases in toxin production. RNA-Seq analysis validated our experimental results, demonstrating increased expression of sporulation-related genes in conjunction with changes in metabolic and regulatory genes, such as a putative carbon starvation protein, CstA. Collectively, these data suggest that butyrate may induce alternative C. difficile survival pathways, modifying its growth ability and virulence to persist in the gut environment. IMPORTANCE Several studies suggest that butyrate may modulate gut infections, such as reducing inflammation caused by the healthcare-associated Clostridioides difficile. While studies in both animal models and human studies correlate high levels of butyrate with reduced C. difficile burden, the direct impact of butyrate on C. difficile remains unclear. Our study demonstrates that butyrate directly influences C. difficile by increasing its sporulation and modifying its metabolism, potentially using butyrate as a biomarker to shift survival strategies in a changing gut environment. These data point to additional therapeutic approaches to combat C. difficile in a butyrate-directed manner.
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Affiliation(s)
| | - Disha Bhattacharjee
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Julian D. Coles
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Sydney Nelson
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - C. Alexis McCollum
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
| | - Anna M. Seekatz
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA
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Sedlar K, Koscova P, Vasylkivska M, Branska B, Kolek J, Kupkova K, Patakova P, Provaznik I. Transcription profiling of butanol producer Clostridium beijerinckii NRRL B-598 using RNA-Seq. BMC Genomics 2018; 19:415. [PMID: 29843608 PMCID: PMC5975590 DOI: 10.1186/s12864-018-4805-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/18/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Thinning supplies of natural resources increase attention to sustainable microbial production of bio-based fuels. The strain Clostridium beijerinckii NRRL B-598 is a relatively well-described butanol producer regarding its genotype and phenotype under various conditions. However, a link between these two levels, lying in the description of the gene regulation mechanisms, is missing for this strain, due to the lack of transcriptomic data. RESULTS In this paper, we present a transcription profile of the strain over the whole fermentation using an RNA-Seq dataset covering six time-points with the current highest dynamic range among solventogenic clostridia. We investigated the accuracy of the genome sequence and particular genome elements, including pseudogenes and prophages. While some pseudogenes were highly expressed, all three identified prophages remained silent. Furthermore, we identified major changes in the transcriptional activity of genes using differential expression analysis between adjacent time-points. We identified functional groups of these significantly regulated genes and together with fermentation and cultivation kinetics captured using liquid chromatography and flow cytometry, we identified basic changes in the metabolism of the strain during fermentation. Interestingly, C. beijerinckii NRRL B-598 demonstrated different behavior in comparison with the closely related strain C. beijerinckii NCIMB 8052 in the latter phases of cultivation. CONCLUSIONS We provided a complex analysis of the C. beijerinckii NRRL B-598 fermentation profile using several technologies, including RNA-Seq. We described the changes in the global metabolism of the strain and confirmed the uniqueness of its behavior. The whole experiment demonstrated a good reproducibility. Therefore, we will be able to repeat the experiment under selected conditions in order to investigate particular metabolic changes and signaling pathways suitable for following targeted engineering.
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Affiliation(s)
- Karel Sedlar
- Department of Biomedical Engineering, Brno University of Technology, Technicka 12, 616 00 Brno, Czechia
| | - Pavlina Koscova
- Department of Biomedical Engineering, Brno University of Technology, Technicka 12, 616 00 Brno, Czechia
| | - Maryna Vasylkivska
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czechia
| | - Barbora Branska
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czechia
| | - Jan Kolek
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czechia
- Institute of Aquaculture and Protection of Waters, University of South Bohemia in České Budějovice, Na Sádkách 1780, 370 05 České Budějovice, Czechia
| | - Kristyna Kupkova
- Department of Biomedical Engineering, Brno University of Technology, Technicka 12, 616 00 Brno, Czechia
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908 USA
| | - Petra Patakova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czechia
| | - Ivo Provaznik
- Department of Biomedical Engineering, Brno University of Technology, Technicka 12, 616 00 Brno, Czechia
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Mathematical modelling of clostridial acetone-butanol-ethanol fermentation. Appl Microbiol Biotechnol 2017; 101:2251-2271. [PMID: 28210797 PMCID: PMC5320022 DOI: 10.1007/s00253-017-8137-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/14/2017] [Accepted: 01/16/2017] [Indexed: 12/24/2022]
Abstract
Clostridial acetone-butanol-ethanol (ABE) fermentation features a remarkable shift in the cellular metabolic activity from acid formation, acidogenesis, to the production of industrial-relevant solvents, solventogensis. In recent decades, mathematical models have been employed to elucidate the complex interlinked regulation and conditions that determine these two distinct metabolic states and govern the transition between them. In this review, we discuss these models with a focus on the mechanisms controlling intra- and extracellular changes between acidogenesis and solventogenesis. In particular, we critically evaluate underlying model assumptions and predictions in the light of current experimental knowledge. Towards this end, we briefly introduce key ideas and assumptions applied in the discussed modelling approaches, but waive a comprehensive mathematical presentation. We distinguish between structural and dynamical models, which will be discussed in their chronological order to illustrate how new biological information facilitates the ‘evolution’ of mathematical models. Mathematical models and their analysis have significantly contributed to our knowledge of ABE fermentation and the underlying regulatory network which spans all levels of biological organization. However, the ties between the different levels of cellular regulation are not well understood. Furthermore, contradictory experimental and theoretical results challenge our current notion of ABE metabolic network structure. Thus, clostridial ABE fermentation still poses theoretical as well as experimental challenges which are best approached in close collaboration between modellers and experimentalists.
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Elucidating the contributions of multiple aldehyde/alcohol dehydrogenases to butanol and ethanol production in Clostridium acetobutylicum. Sci Rep 2016; 6:28189. [PMID: 27321949 PMCID: PMC4913296 DOI: 10.1038/srep28189] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 06/01/2016] [Indexed: 01/07/2023] Open
Abstract
Ethanol and butanol biosynthesis in Clostridium acetobutylicum share common aldehyde/alcohol dehydrogenases. However, little is known about the relative contributions of these multiple dehydrogenases to ethanol and butanol production respectively. The contributions of six aldehyde/alcohol dehydrogenases of C. acetobutylicum on butanol and ethanol production were evaluated through inactivation of the corresponding genes respectively. For butanol production, the relative contributions from these enzymes were: AdhE1 > BdhB > BdhA ≈ YqhD > SMB_P058 > AdhE2. For ethanol production, the contributions were: AdhE1 > BdhB > YqhD > SMB_P058 > AdhE2 > BdhA. AdhE1 and BdhB are two essential enzymes for butanol and ethanol production. AdhE1 was relatively specific for butanol production over ethanol, while BdhB, YqhD, and SMB_P058 favor ethanol production over butanol. Butanol synthesis was increased in the adhE2 mutant, which had a higher butanol/ethanol ratio (8.15:1) compared with wild type strain (6.65:1). Both the SMB_P058 mutant and yqhD mutant produced less ethanol without loss of butanol formation, which led to higher butanol/ethanol ratio, 10.12:1 and 10.17:1, respectively. To engineer a more efficient butanol-producing strain, adhE1 could be overexpressed, furthermore, adhE2, SMB_P058, yqhD are promising gene inactivation targets. This work provides useful information guiding future strain improvement for butanol production.
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Alcohol Selectivity in a Synthetic Thermophilic n-Butanol Pathway Is Driven by Biocatalytic and Thermostability Characteristics of Constituent Enzymes. Appl Environ Microbiol 2015; 81:7187-200. [PMID: 26253677 DOI: 10.1128/aem.02028-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 07/29/2015] [Indexed: 02/06/2023] Open
Abstract
n-Butanol is generated as a natural product of metabolism by several microorganisms, but almost all grow at mesophilic temperatures. A synthetic pathway for n-butanol production from acetyl coenzyme A (acetyl-CoA) that functioned at 70°C was assembled in vitro from enzymes recruited from thermophilic bacteria to inform efforts for engineering butanol production into thermophilic hosts. Recombinant versions of eight thermophilic enzymes (β-ketothiolase [Thl], 3-hydroxybutyryl-CoA dehydrogenase [Hbd], and 3-hydroxybutyryl-CoA dehydratase [Crt] from Caldanaerobacter subterraneus subsp. tengcongensis; trans-2-enoyl-CoA reductase [Ter] from Spirochaeta thermophila; bifunctional acetaldehyde dehydrogenase/alcohol dehydrogenase [AdhE] from Clostridium thermocellum; and AdhE, aldehyde dehydrogenase [Bad], and butanol dehydrogenase [Bdh] from Thermoanaerobacter sp. strain X514) were utilized to examine three possible pathways for n-butanol. These pathways differed in the two steps required to convert butyryl-CoA to n-butanol: Thl-Hbd-Crt-Ter-AdhE (C. thermocellum), Thl-Hbd-Crt-Ter-AdhE (Thermoanaerobacter X514), and Thl-Hbd-Crt-Ter-Bad-Bdh. n-Butanol was produced at 70°C, but with different amounts of ethanol as a coproduct, because of the broad substrate specificities of AdhE, Bad, and Bdh. A reaction kinetics model, validated via comparison to in vitro experiments, was used to determine relative enzyme ratios needed to maximize n-butanol production. By using large relative amounts of Thl and Hbd and small amounts of Bad and Bdh, >70% conversion to n-butanol was observed in vitro, but with a 60% decrease in the predicted pathway flux. With more-selective hypothetical versions of Bad and Bdh, >70% conversion to n-butanol is predicted, with a 19% increase in pathway flux. Thus, more-selective thermophilic versions of Bad, Bdh, and AdhE are needed to fully exploit biocatalytic n-butanol production at elevated temperatures.
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Millat T, Janssen H, Bahl H, Fischer RJ, Wolkenhauer O. Integrative modelling of pH-dependent enzyme activity and transcriptomic regulation of the acetone-butanol-ethanol fermentation of Clostridium acetobutylicum in continuous culture. Microb Biotechnol 2013; 6:526-39. [PMID: 23332010 PMCID: PMC3918155 DOI: 10.1111/1751-7915.12033] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 12/10/2012] [Indexed: 11/30/2022] Open
Abstract
In a continuous culture under phosphate limitation the metabolism of Clostridium acetobutylicum depends on the external pH level. By comparing seven steady-state conditions between pH 5.7 and pH 4.5 we show that the switch from acidogenesis to solventogenesis occurs between pH 5.3 and pH 5.0 with an intermediate state at pH 5.1. Here, an integrative study is presented investigating how a changing external pH level affects the clostridial acetone–butanol–ethanol (ABE) fermentation pathway. This is of particular interest as the biotechnological production of n-butanol as biofuel has recently returned into the focus of industrial applications. One prerequisite is the furthering of the knowledge of the factors determining the solvent production and their integrative regulations. We have mathematically analysed the influence of pH-dependent specific enzyme activities of branch points of the metabolism on the product formation. This kinetic regulation was compared with transcriptomic regulation regarding gene transcription and the proteomic profile. Furthermore, both regulatory mechanisms were combined yielding a detailed projection of their individual and joint effects on the product formation. The resulting model represents an important platform for future developments of industrial butanol production based on C. acetobutylicum.
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Affiliation(s)
- Thomas Millat
- Department of Systems Biology & Bioinformatics, Institute of Computer Science, University of Rostock, University of Rostock, Ulmenstr. 69, 18051, Rostock, Germany.
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Thorn GJ, King JR, Jabbari S. pH-induced gene regulation of solvent production by Clostridium acetobutylicum in continuous culture: parameter estimation and sporulation modelling. Math Biosci 2012. [PMID: 23201580 PMCID: PMC3547174 DOI: 10.1016/j.mbs.2012.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The acetone-butanol (AB) fermentation process in the anaerobic endospore-forming Gram-positive bacterium Clostridium acetobutylicum is useful as a producer of biofuels, particularly butanol. Recent work has concentrated on trying to improve the efficiency of the fermentation method, either through changes in the environmental conditions or by modifying the genome to selectively favour the production of one particular solvent over others. Fermentation of glucose by C. acetobutylicum occurs in two stages: initially the acids acetate and butyrate are produced and excreted and then, as the external pH falls, acetate and butyrate are ingested and further metabolised into the solvents acetone, butanol and ethanol. In order to optimise butanol production, it is important to understand how pH affects the enzyme-controlled reactions in the metabolism process. We adapt an ordinary differential equation model of the metabolic network with regulation at the genetic level for the required enzymes; parametrising the model using experimental data generated from continuous culture, we improve on previous point predictions (S. Haus, S. Jabbari, T. Millat, H. Janssen, R.-J. Fisher, H. Bahl, J. R. King, O. Wolkenhauer, A systems biology approach to investigate the effect of pH-induced gene regulation on solvent production by Clostridium acetobutylicum in continuous culture, BMC Systems Biology 5 (2011)) [1] both by using a different optimisation approach and by computing confidence intervals and correlation coefficients. We find in particular that the parameters are ill-determined from the data and that two separate clusters of parameters appear correlated, reflecting the importance of two metabolic intermediates. We extend the model further to include another aspect of the clostridial survival mechanism, sporulation, and by computation of the Akaike Information Criterion values find that the there is some evidence for the presence of sporulation during the shift.
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Affiliation(s)
- Graeme J Thorn
- School of Mathematical Sciences, Mathematical Sciences Building, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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Schühle K, Heider J. Acetone and butanone metabolism of the denitrifying bacterium "Aromatoleum aromaticum" demonstrates novel biochemical properties of an ATP-dependent aliphatic ketone carboxylase. J Bacteriol 2012; 194:131-41. [PMID: 22020645 PMCID: PMC3256595 DOI: 10.1128/jb.05895-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 10/13/2011] [Indexed: 11/20/2022] Open
Abstract
The anaerobic and aerobic metabolism of acetone and butanone in the betaproteobacterium "Aromatoleum aromaticum" is initiated by their ATP-dependent carboxylation to acetoacetate and 3-oxopentanoic acid, respectively. Both reactions are catalyzed by the same enzyme, acetone carboxylase, which was purified and characterized. Acetone carboxylase is highly induced under growth on acetone or butanone and accounts for at least 5.5% of total cell protein. The enzyme consists of three subunits of 85, 75, and 20 kDa, respectively, in a (αβγ)(2) composition and contains 1 Zn and 2 Fe per heterohexamer but no organic cofactors. Chromatographic analysis of the ATP hydrolysis products indicated that ATP was exclusively cleaved to AMP and 2 P(i). The stoichiometry was determined to be 2 ATP consumed per acetone carboxylated. Purified acetone carboxylase from A. aromaticum catalyzes the carboxylation of acetone and butanone as the only substrates. However, the enzyme shows induced (uncoupled) ATPase activity with many other substrates that were not carboxylated. Acetone carboxylase is a member of a protein family that also contains acetone carboxylases of various other organisms, acetophenone carboxylase of A. aromaticum, and ATP-dependent hydantoinases/oxoprolinases. While the members of this family share several characteristic features, they differ with respect to the products of ATP hydrolysis, subunit composition, and metal content.
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Affiliation(s)
- Karola Schühle
- Laboratory for Microbiology, University of Marburg, Marburg, Germany
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Hu S, Zheng H, Gu Y, Zhao J, Zhang W, Yang Y, Wang S, Zhao G, Yang S, Jiang W. Comparative genomic and transcriptomic analysis revealed genetic characteristics related to solvent formation and xylose utilization in Clostridium acetobutylicum EA 2018. BMC Genomics 2011; 12:93. [PMID: 21284892 PMCID: PMC3044671 DOI: 10.1186/1471-2164-12-93] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 02/02/2011] [Indexed: 12/17/2022] Open
Abstract
Background Clostridium acetobutylicum, a gram-positive and spore-forming anaerobe, is a major strain for the fermentative production of acetone, butanol and ethanol. But a previously isolated hyper-butanol producing strain C. acetobutylicum EA 2018 does not produce spores and has greater capability of solvent production, especially for butanol, than the type strain C. acetobutylicum ATCC 824. Results Complete genome of C. acetobutylicum EA 2018 was sequenced using Roche 454 pyrosequencing. Genomic comparison with ATCC 824 identified many variations which may contribute to the hyper-butanol producing characteristics in the EA 2018 strain, including a total of 46 deletion sites and 26 insertion sites. In addition, transcriptomic profiling of gene expression in EA 2018 relative to that of ATCC824 revealed expression-level changes of several key genes related to solvent formation. For example, spo0A and adhEII have higher expression level, and most of the acid formation related genes have lower expression level in EA 2018. Interestingly, the results also showed that the variation in CEA_G2622 (CAC2613 in ATCC 824), a putative transcriptional regulator involved in xylose utilization, might accelerate utilization of substrate xylose. Conclusions Comparative analysis of C. acetobutylicum hyper-butanol producing strain EA 2018 and type strain ATCC 824 at both genomic and transcriptomic levels, for the first time, provides molecular-level understanding of non-sporulation, higher solvent production and enhanced xylose utilization in the mutant EA 2018. The information could be valuable for further genetic modification of C. acetobutylicum for more effective butanol production.
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Affiliation(s)
- Shiyuan Hu
- Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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Haus S, Jabbari S, Millat T, Janssen H, Fischer RJ, Bahl H, King JR, Wolkenhauer O. A systems biology approach to investigate the effect of pH-induced gene regulation on solvent production by Clostridium acetobutylicum in continuous culture. BMC SYSTEMS BIOLOGY 2011; 5:10. [PMID: 21247470 PMCID: PMC3037857 DOI: 10.1186/1752-0509-5-10] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 01/19/2011] [Indexed: 12/16/2022]
Abstract
BACKGROUND Clostridium acetobutylicum is an anaerobic bacterium which is known for its solvent-producing capabilities, namely regarding the bulk chemicals acetone and butanol, the latter being a highly efficient biofuel. For butanol production by C. acetobutylicum to be optimized and exploited on an industrial scale, the effect of pH-induced gene regulation on solvent production by C. acetobutylicum in continuous culture must be understood as fully as possible. RESULTS We present an ordinary differential equation model combining the metabolic network governing solvent production with regulation at the genetic level of the enzymes required for this process. Parameterizing the model with experimental data from continuous culture, we demonstrate the influence of pH upon fermentation products: at high pH (pH 5.7) acids are the dominant product while at low pH (pH 4.5) this switches to solvents. Through steady-state analyses of the model we focus our investigations on how alteration in gene expression of C. acetobutylicum could be exploited to increase butanol yield in a continuous culture fermentation. CONCLUSIONS Incorporating gene regulation into the model of solvent production by C. acetobutylicum enables an accurate representation of the pH-induced switch to solvent production to be obtained and theoretical investigations of possible synthetic-biology approaches to be pursued. Steady-state analyses suggest that, to increase butanol yield, alterations in the expression of single solvent-associated genes are insufficient; a more complex approach targeting two or more genes is required.
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Affiliation(s)
- Sylvia Haus
- University of Rostock, Institute of Computer Science, Department of Systems Biology & Bioinformatics, 18051 Rostock, Germany
| | - Sara Jabbari
- University of Nottingham, School of Mathematical Sciences, University Park, Nottingham, NG7 2RD, UK
| | - Thomas Millat
- University of Rostock, Institute of Computer Science, Department of Systems Biology & Bioinformatics, 18051 Rostock, Germany
| | - Holger Janssen
- University of Rostock, Institute of Biological Sciences, Division of Microbiology, 18051 Rostock, Germany
| | - Ralf-Jörg Fischer
- University of Rostock, Institute of Biological Sciences, Division of Microbiology, 18051 Rostock, Germany
| | - Hubert Bahl
- University of Rostock, Institute of Biological Sciences, Division of Microbiology, 18051 Rostock, Germany
| | - John R King
- University of Nottingham, School of Mathematical Sciences, University Park, Nottingham, NG7 2RD, UK
| | - Olaf Wolkenhauer
- University of Rostock, Institute of Computer Science, Department of Systems Biology & Bioinformatics, 18051 Rostock, Germany
- Stellenbosch Institute for Advanced Study, Stellenbosch 7600, South Africa
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Bruant G, Lévesque MJ, Peter C, Guiot SR, Masson L. Genomic analysis of carbon monoxide utilization and butanol production by Clostridium carboxidivorans strain P7. PLoS One 2010; 5:e13033. [PMID: 20885952 PMCID: PMC2946384 DOI: 10.1371/journal.pone.0013033] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 09/02/2010] [Indexed: 11/19/2022] Open
Abstract
Increasing demand for the production of renewable fuels has recently generated a particular interest in microbial production of butanol. Anaerobic bacteria, such as Clostridium spp., can naturally convert carbohydrates into a variety of primary products, including alcohols like butanol. The genetics of microorganisms like Clostridium acetobutylicum have been well studied and their solvent-producing metabolic pathways characterized. In contrast, less is known about the genetics of Clostridium spp. capable of converting syngas or its individual components into solvents. In this study, the type of strain of a new solventogenic Clostridium species, C. carboxidivorans, was genetically characterized by genome sequencing. C. carboxidivorans strain P7(T) possessed a complete Wood-Ljungdahl pathway gene cluster, involving CO and CO(2) fixation and conversion to acetyl-CoA. Moreover, with the exception of an acetone production pathway, all the genetic determinants of canonical ABE metabolic pathways for acetate, butyrate, ethanol and butanol production were present in the P7(T) chromosome. The functionality of these pathways was also confirmed by growth of P7(T) on CO and production of CO(2) as well as volatile fatty acids (acetate and butyrate) and solvents (ethanol and butanol). P7(T) was also found to harbour a 19 Kbp plasmid, which did not include essential or butanol production related genes. This study has generated in depth knowledge of the P7(T) genome, which will be helpful in developing metabolic engineering strategies to improve C. carboxidivorans's natural capacity to produce potential biofuels from syngas.
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Affiliation(s)
- Guillaume Bruant
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, Canada
| | - Marie-Josée Lévesque
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, Canada
| | - Chardeen Peter
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, Canada
| | - Serge R. Guiot
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, Canada
- Département de Microbiologie et Immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Luke Masson
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, Canada
- Département de Microbiologie et Immunologie, Université de Montréal, Montréal, Quebec, Canada
- * E-mail:
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Feustel L, Nakotte S, Dürre P. Characterization and development of two reporter gene systems for Clostridium acetobutylicum. Appl Environ Microbiol 2004; 70:798-803. [PMID: 14766557 PMCID: PMC348925 DOI: 10.1128/aem.70.2.798-803.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The use of lacZ from Thermoanaerobacterium thermosulfurigenes (encoding beta-galactosidase) and lucB from Photinus pyralis (encoding luciferase) as reporter genes in Clostridium acetobutylicum was analyzed with promoters of genes required for solventogenesis and acidogenesis. Both systems proved to be well suited and allowed the detection of differences in promoter strength at least up to 100-fold. The luciferase assay could be performed much faster and comes close to online measurement. Resequencing of lacZ revealed a sequence error in the original database entry, which resulted in beta-galactosidase with an additional 31 amino acids. Cutting off part of the gene encoding this C terminus resulted in decreased enzyme activity. The lacZ reporter data showed that bdhA (encoding butanol dehydrogenase A) is expressed during the early growth phase, followed by sol (encoding butyraldehyde/butanol dehydrogenase E and coenzyme A transferase) and bdhB (encoding butanol dehydrogenase B) expression. adc (encoding acetoacetate decarboxylase) was also induced early. There is about a 100-fold difference in expression between adc and bdhB (higher) and bdhA and the sol operon (lower). The lucB reporter activity could be increased 10-fold by the addition of ATP to the assay. Washing of the cells proved to be important in order to prevent a red shift of bioluminescence in an acidic environment (for reliable data). lucB reporter measurements confirmed the expression pattern of the sol and ptb-buk (encoding phosphotransbutyrylase and butyrate kinase) operons as determined by the lacZ reporter and showed that the expression level from the ptb promoter is 59-fold higher than that from the sol operon promoter.
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Affiliation(s)
- Lothar Feustel
- Mikrobiologie und Biotechnologie, Universität Ulm, 89069 Ulm, Germany
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Scotcher MC, Huang KX, Harrison ML, Rudolph FB, Bennett GN. Sequences affecting the regulation of solvent production in Clostridium acetobutylicum. J Ind Microbiol Biotechnol 2003; 30:414-20. [PMID: 12774196 DOI: 10.1007/s10295-003-0057-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2002] [Accepted: 03/27/2003] [Indexed: 10/26/2022]
Abstract
The high solvent phenotype of Clostridium acetobutylicum mutants B and H was complemented by the introduction of a plasmid that contains either an intact or partially-deleted copy of solR, restoring acetone and butanol production to wild-type levels. This demonstrates that the solR open reading frame on pSOLThi is not required to restore solvent levels. The promoter region upstream of alcohol dehydrogense E (adhE) was examined in efforts to identify sites that play major roles in the control of expression. A series of adhE promoter fragments was constructed and the expression of each in acid- and solvent-phases of growth was analyzed using a chloramphenicol acetyl-transferase reporter system. Our results show that a region beyond the 0A box is needed for full induction of the promoter. Additionally, we show that the presence of sequences around a possible processing site designated S2 may have a negative role in the regulation of adhE expression.
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Affiliation(s)
- Miles C Scotcher
- Department of Biochemistry and Cell Biology, MS 140, Rice University, 6100 Main Street, Houston, TX 77005, USA
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15
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Hügler M, Menendez C, Schägger H, Fuchs G. Malonyl-coenzyme A reductase from Chloroflexus aurantiacus, a key enzyme of the 3-hydroxypropionate cycle for autotrophic CO(2) fixation. J Bacteriol 2002; 184:2404-10. [PMID: 11948153 PMCID: PMC134993 DOI: 10.1128/jb.184.9.2404-2410.2002] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 3-hydroxypropionate cycle is a new autotrophic CO(2) fixation pathway in Chloroflexus aurantiacus and some archaebacteria. The initial step is acetyl-coenzyme A (CoA) carboxylation to malonyl-CoA by acetyl-CoA carboxylase, followed by NADPH-dependent reduction of malonyl-CoA to 3-hydroxypropionate. This reduction step was studied in Chloroflexus aurantiacus. A new enzyme was purified, malonyl-CoA reductase, which catalyzed the two-step reduction malonyl-CoA + NADPH + H(+) --> malonate semialdehyde + NADP(+) + CoA and malonate semialdehyde + NADPH + H(+) --> 3-hydroxypropionate + NADP(+). The bifunctional enzyme (aldehyde dehydrogenase and alcohol dehydrogenase) had a native molecular mass of 300 kDa and consisted of a single large subunit of 145 kDa, suggesting an alpha(2) composition. The N-terminal amino acid sequence was determined, and the incomplete gene was identified in the genome database. Obviously, the enzyme consists of an N-terminal short-chain alcohol dehydrogenase domain and a C-terminal aldehyde dehydrogenase domain. No indication of the presence of a prosthetic group was obtained; Mg(2+) and Fe(2+) stimulated and EDTA inhibited activity. The enzyme was highly specific for its substrates, with apparent K(m) values of 30 microM malonyl-CoA and 25 microM NADPH and a turnover number of 25 s(-1) subunit(-1). The specific activity in autotrophically grown cells was 0.08 micromol of malonyl-CoA reduced min(-1) (mg of protein)(-1), compared to 0.03 micromol min(-1) (mg of protein)(-1) in heterotrophically grown cells, indicating downregulation under heterotrophic conditions. Malonyl-CoA reductase is not required in any other known pathway and therefore can be taken as a characteristic enzyme of the 3-hydroxypropionate cycle. Furthermore, the enzyme may be useful for production of 3-hydroxypropionate and for a coupled spectrophotometric assay for activity screening of acetyl-CoA carboxylase, a target enzyme of potent herbicides.
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Affiliation(s)
- Michael Hügler
- Mikrobiologie, Institut für Biologie II, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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Thormann K, Feustel L, Lorenz K, Nakotte S, Dürre P. Control of butanol formation in Clostridium acetobutylicum by transcriptional activation. J Bacteriol 2002; 184:1966-73. [PMID: 11889105 PMCID: PMC134926 DOI: 10.1128/jb.184.7.1966-1973.2002] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The sol operon of Clostridium acetobutylicum is the essential transcription unit for formation of the solvents butanol and acetone. The recent proposal that transcriptional regulation of this operon is controlled by the repressor Orf5/SolR (R. V. Nair, E. M. Green, D. E. Watson, G. N. Bennett, and E. T. Papoutsakis, J. Bacteriol. 181:319-330, 1999) was found to be incorrect. Instead, regulation depends on activation, most probably by the multivalent transcription factor Spo0A. The operon is transcribed from a single promoter. A second signal identified in primer extension studies results from mRNA processing and can be observed only in the natural host, not in a heterologous host. The first structural gene in the operon (adhE, encoding a bifunctional butyraldehyde/butanol dehydrogenase) is translated into two different proteins, the mature AdhE enzyme and the separate butanol dehydrogenase domain. The promoter of the sol operon is preceded by three imperfect repeats and a putative Spo0A-binding motif, which partially overlaps with repeat 3 (R3). Reporter gene analysis performed with the lacZ gene of Thermoanaerobacterium thermosulfurigenes and targeted mutations of the regulatory region revealed that the putative Spo0A-binding motif, R3, and R1 are essential for control. The data obtained also indicate that an additional activator protein is involved.
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Affiliation(s)
- Kai Thormann
- Mikrobiologie und Biotechnologie, Universität Ulm, 89069 Ulm, Germany
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Fontaine L, Meynial-Salles I, Girbal L, Yang X, Croux C, Soucaille P. Molecular characterization and transcriptional analysis of adhE2, the gene encoding the NADH-dependent aldehyde/alcohol dehydrogenase responsible for butanol production in alcohologenic cultures of Clostridium acetobutylicum ATCC 824. J Bacteriol 2002; 184:821-30. [PMID: 11790753 PMCID: PMC139506 DOI: 10.1128/jb.184.3.821-830.2002] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adhE2 gene of Clostridium acetobutylicum ATCC 824, coding for an aldehyde/alcohol dehydrogenase (AADH), was characterized from molecular and biochemical points of view. The 2,577-bp adhE2 codes for a 94.4-kDa protein. adhE2 is expressed, as a monocistronic operon, in alcohologenic cultures and not in solventogenic cultures. Primer extension analysis identified two transcriptional start sites 160 and 215 bp upstream of the adhE2 start codon. The expression of adhE2 from a plasmid in the DG1 mutant of C. acetobutylicum, a mutant cured of the pSOL1 megaplasmid, restored butanol production and provided elevated activities of NADH-dependent butyraldehyde and butanol dehydrogenases. The recombinant AdhE2 protein expressed in E. coli as a Strep-tag fusion protein and purified to homogeneity also demonstrated NADH-dependent butyraldehyde and butanol dehydrogenase activities. This is the second AADH identified in C. acetobutylicum ATCC 824, and to our knowledge this is the first example of a bacterium with two AADHs. It is noteworthy that the two corresponding genes, adhE and adhE2, are carried by the pSOL1 megaplasmid of C. acetobutylicum ATCC 824.
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Affiliation(s)
- Lisa Fontaine
- Centre de Bioingénierie Gilbert Durand, Laboratoire de Biotechnologies-Bioprocédés, UMR CNRS 5504, UR INRA 792, INSA, 31077 Toulouse cedex 4, France
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Nölling J, Breton G, Omelchenko MV, Makarova KS, Zeng Q, Gibson R, Lee HM, Dubois J, Qiu D, Hitti J, Wolf YI, Tatusov RL, Sabathe F, Doucette-Stamm L, Soucaille P, Daly MJ, Bennett GN, Koonin EV, Smith DR. Genome sequence and comparative analysis of the solvent-producing bacterium Clostridium acetobutylicum. J Bacteriol 2001; 183:4823-38. [PMID: 11466286 PMCID: PMC99537 DOI: 10.1128/jb.183.16.4823-4838.2001] [Citation(s) in RCA: 636] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome sequence of the solvent-producing bacterium Clostridium acetobutylicum ATCC 824 has been determined by the shotgun approach. The genome consists of a 3.94-Mb chromosome and a 192-kb megaplasmid that contains the majority of genes responsible for solvent production. Comparison of C. acetobutylicum to Bacillus subtilis reveals significant local conservation of gene order, which has not been seen in comparisons of other genomes with similar, or, in some cases closer, phylogenetic proximity. This conservation allows the prediction of many previously undetected operons in both bacteria. However, the C. acetobutylicum genome also contains a significant number of predicted operons that are shared with distantly related bacteria and archaea but not with B. subtilis. Phylogenetic analysis is compatible with the dissemination of such operons by horizontal transfer. The enzymes of the solventogenesis pathway and of the cellulosome of C. acetobutylicum comprise a new set of metabolic capacities not previously represented in the collection of complete genomes. These enzymes show a complex pattern of evolutionary affinities, emphasizing the role of lateral gene exchange in the evolution of the unique metabolic profile of the bacterium. Many of the sporulation genes identified in B. subtilis are missing in C. acetobutylicum, which suggests major differences in the sporulation process. Thus, comparative analysis reveals both significant conservation of the genome organization and pronounced differences in many systems that reflect unique adaptive strategies of the two gram-positive bacteria.
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Affiliation(s)
- J Nölling
- GTC Sequencing Center, Genome Therapeutics Corporation, Waltham, Massachusetts 02453, USA
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Karlsson S, Lindberg A, Norin E, Burman LG, Akerlund T. Toxins, butyric acid, and other short-chain fatty acids are coordinately expressed and down-regulated by cysteine in Clostridium difficile. Infect Immun 2000; 68:5881-8. [PMID: 10992498 PMCID: PMC101550 DOI: 10.1128/iai.68.10.5881-5888.2000] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It was recently found that a mixture of nine amino acids down-regulate Clostridium difficile toxin production when added to peptone yeast extract (PY) cultures of strain VPI 10463 (S. Karlsson, L. G. Burman, and T. Akerlund, Microbiology 145:1683-1693, 1999). In the present study, seven of these amino acids were found to exhibit a moderate suppression of toxin production, whereas proline and particularly cysteine had the greatest impact, on both reference strains (n = 6) and clinical isolates (n = 28) of C. difficile (>99% suppression by cysteine in the highest toxin-producing strain). Also, cysteine derivatives such as acetylcysteine, glutathione, and cystine effectively down-regulated toxin expression. An impact of both cysteine and cystine but not of thioglycolate on toxin yield indicated that toxin expression was not regulated by the oxidation-reduction potential. Several metabolic pathways, including butyric acid and butanol production, were coinduced with the toxins in PY and down-regulated by cysteine. The enzyme 3-hydroxybutyryl coenzyme A dehydrogenase, a key enzyme in solventogenesis in Clostridium acetobutylicum, was among the most up-regulated proteins during high toxin production. The addition of butyric acid to various growth media induced toxin production, whereas the addition of butanol had the opposite effect. The results indicate a coupling between specific metabolic processes and toxin expression in C. difficile and that certain amino acids can alter these pathways coordinately. We speculate that down-regulation of toxin production by the administration of such amino acids to the colon may become a novel approach to prophylaxis and therapy for C. difficile-associated diarrhea.
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Affiliation(s)
- S Karlsson
- Department of Bacteriology, Swedish Institute for Infectious Disease Control, S-171 82, Solna
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Tummala SB, Welker NE, Papoutsakis ET. Development and characterization of a gene expression reporter system for Clostridium acetobutylicum ATCC 824. Appl Environ Microbiol 1999; 65:3793-9. [PMID: 10473377 PMCID: PMC99702 DOI: 10.1128/aem.65.9.3793-3799.1999] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A gene expression reporter system (pHT3) for Clostridium acetobutylicum ATCC 824 was developed by using the lacZ gene from Thermoanaerobacterium thermosulfurogenes EM1 as the reporter gene. In order to test the reporter system, promoters of three key metabolic pathway genes, ptb (coding for phosphotransbutyrylase), thl (coding for thiolase), and adc (coding for acetoacetate decarboxylase), were cloned upstream of the reporter gene in pHT3 in order to construct vectors pHT4, pHT5, and pHTA, respectively. Detection of beta-galactosidase activity in time course studies performed with strains ATCC 824(pHT4), ATCC 824(pHT5), and ATCC 824(pHTA) demonstrated that the reporter gene produced a functional beta-galactosidase in C. acetobutylicum. In addition, time course studies revealed differences in the beta-galactosidase specific activity profiles of strains ATCC 824(pHT4), ATCC 824(pHT5), and ATCC 824(pHTA), suggesting that the reporter system developed in this study is able to effectively distinguish between different promoters. The stability of the beta-galactosidase produced by the reporter gene was also examined with strains ATCC 824(pHT4) and ATCC 824(pHT5) by using chloramphenicol treatment to inhibit protein synthesis. The data indicated that the beta-galactosidase produced by the lacZ gene from T. thermosulfurogenes EM1 was stable in the exponential phase of growth. In pH-controlled fermentations of ATCC 824(pHT4), the kinetics of beta-galactosidase formation from the ptb promoter and phosphotransbutyrylase formation from its own autologous promoter were found to be similar.
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Affiliation(s)
- S B Tummala
- Department of Chemical Engineering, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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Nair RV, Green EM, Watson DE, Bennett GN, Papoutsakis ET. Regulation of the sol locus genes for butanol and acetone formation in Clostridium acetobutylicum ATCC 824 by a putative transcriptional repressor. J Bacteriol 1999; 181:319-30. [PMID: 9864345 PMCID: PMC103564 DOI: 10.1128/jb.181.1.319-330.1999] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A gene (orf1, now designated solR) previously identified upstream of the aldehyde/alcohol dehydrogenase gene aad (R. V. Nair, G. N. Bennett, and E. T. Papoutsakis, J. Bacteriol. 176:871-885, 1994) was found to encode a repressor of the sol locus (aad, ctfA, ctfB and adc) genes for butanol and acetone formation in Clostridium acetobutylicum ATCC 824. Primer extension analysis identified a transcriptional start site 35 bp upstream of the solR start codon. Amino acid comparisons of SolR identified a potential helix-turn-helix DNA-binding motif in the C-terminal half towards the center of the protein, suggesting a regulatory role. Overexpression of SolR in strain ATCC 824(pCO1) resulted in a solvent-negative phenotype owing to its deleterious effect on the transcription of the sol locus genes. Inactivation of solR in C. acetobutylicum via homologous recombination yielded mutants B and H (ATCC 824 solR::pO1X) which exhibited deregulated solvent production characterized by increased flux towards butanol and acetone formation, earlier induction of aad, lower overall acid production, markedly improved yields of solvents on glucose, a prolonged solvent production phase, and increased biomass accumulation compared to those of the wild-type strain.
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Affiliation(s)
- R V Nair
- Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208, USA
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Wong J, Bennett GN. The effect of novobiocin on solvent production by Clostridium acetobutylicum. JOURNAL OF INDUSTRIAL MICROBIOLOGY 1996; 16:354-9. [PMID: 8987493 DOI: 10.1007/bf01570115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cells of Clostridium acetobutylicum treated with novoblocin, a DNA gyrase inhibitor, produced higher butyrate levels and lower solvent levels with acetone being the most affected. Seven enzyme activities involved in acid and solvent production were analyzed. Among them, only CoA transferase, required for acetone formation and acid uptake, experienced a significant decrease in activity. As in Escherichia coli and Bacillus subtilis, DNA from C. acetobutylicum became less negatively supercoiled in the early stationary phase (solventogenic stage), as shown by analysis of linking number of a reporter plasmid by agarose gel electrophoresis in the presence of chloroquine.
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Affiliation(s)
- J Wong
- Rice University, Department of Biochemistry and Cell Biology, Houston, TX 77005-1892, USA
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