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Branska B, Pechacova Z, Kolek J, Vasylkivska M, Patakova P. Flow cytometry analysis of Clostridium beijerinckii NRRL B-598 populations exhibiting different phenotypes induced by changes in cultivation conditions. Biotechnol Biofuels 2018; 11:99. [PMID: 29632557 PMCID: PMC5887253 DOI: 10.1186/s13068-018-1096-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 03/26/2018] [Indexed: 05/08/2023]
Abstract
BACKGROUND Biobutanol production by clostridia via the acetone-butanol-ethanol (ABE) pathway is a promising future technology in bioenergetics , but identifying key regulatory mechanisms for this pathway is essential in order to construct industrially relevant strains with high tolerance and productivity. We have applied flow cytometric analysis to C. beijerinckii NRRL B-598 and carried out comparative screening of physiological changes in terms of viability under different cultivation conditions to determine its dependence on particular stages of the life cycle and the concentration of butanol. RESULTS Dual staining by propidium iodide (PI) and carboxyfluorescein diacetate (CFDA) provided separation of cells into four subpopulations with different abilities to take up PI and cleave CFDA, reflecting different physiological states. The development of a staining pattern during ABE fermentation showed an apparent decline in viability, starting at the pH shift and onset of solventogenesis, although an appreciable proportion of cells continued to proliferate. This was observed for sporulating as well as non-sporulating phenotypes at low solvent concentrations, suggesting that the increase in percentage of inactive cells was not a result of solvent toxicity or a transition from vegetative to sporulating stages. Additionally, the sporulating phenotype was challenged with butanol and cultivation with a lower starting pH was performed; in both these experiments similar trends were obtained-viability declined after the pH breakpoint, independent of the actual butanol concentration in the medium. Production characteristics of both sporulating and non-sporulating phenotypes were comparable, showing that in C. beijerinckii NRRL B-598, solventogenesis was not conditional on sporulation. CONCLUSION We have shown that the decline in C. beijerinckii NRRL B-598 culture viability during ABE fermentation was not only the result of accumulated toxic metabolites, but might also be associated with a special survival strategy triggered by pH change.
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Affiliation(s)
- Barbora Branska
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czech Republic
| | - Zora Pechacova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czech Republic
| | - Jan Kolek
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czech Republic
| | - Maryna Vasylkivska
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czech Republic
| | - Petra Patakova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague, Czech Republic
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Nanda S, Golemi-Kotra D, McDermott JC, Dalai AK, Gökalp I, Kozinski JA. Fermentative production of butanol: Perspectives on synthetic biology. N Biotechnol 2017; 37:210-221. [DOI: 10.1016/j.nbt.2017.02.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 02/20/2017] [Accepted: 02/22/2017] [Indexed: 11/25/2022]
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3
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Liu Z, Qiao K, Tian L, Zhang Q, Liu ZY, Li FL. Spontaneous large-scale autolysis in Clostridium acetobutylicum contributes to generation of more spores. Front Microbiol 2015; 6:950. [PMID: 26441884 PMCID: PMC4563875 DOI: 10.3389/fmicb.2015.00950] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 08/27/2015] [Indexed: 12/15/2022] Open
Abstract
Autolysis is a widespread phenomenon in bacteria. In batch fermentation of Clostridium acetobutylicum ATCC 824, there is a spontaneous large-scale autolysis phenomenon with significant decrease of cell density immediately after exponential phase. To unravel the role of autolysis, an autolysin-coding gene, CA_C0554, was disrupted by using ClosTron system to obtain the mutant C. acetobutylicum lyc::int(72). The lower final cell density and faster cell density decrease rate of C. acetobutylicum ATCC 824 than those of C. acetobutylicum lyc::int(72) indicates that CA_C0554 was an important but not the sole autolysin-coding gene responding for the large-scale autolysis. Similar glucose utilization and solvents production but obvious lower cell density of C. acetobutylicum ATCC 824 comparing to C. acetobutylicum lyc::int(72) suggests that lysed C. acetobutylicum ATCC 824 cells were metabolic inactive. On the contrary, the spore density of C. acetobutylicum ATCC 824 is 26.1% higher than that of C. acetobutylicum lyc::int(72) in the final culture broth of batch fermentation. We speculated that spontaneous autolysis of metabolic-inactive cells provided nutrients for the sporulating cells. The present study suggests that one important biological role of spontaneous large-scale autolysis in C. acetobutylicum ATCC 824 batch fermentation is contributing to generation of more spores during sporulation.
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Affiliation(s)
- Zhen Liu
- Key Laboratory of Biofuels and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology - Chinese Academy of Sciences Qingdao, China
| | - Kai Qiao
- Sinopec Fushun Research Institute of Petroleum and Petrochemicals Fushun, China
| | - Lei Tian
- Key Laboratory of Biofuels and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology - Chinese Academy of Sciences Qingdao, China
| | - Quan Zhang
- Sinopec Fushun Research Institute of Petroleum and Petrochemicals Fushun, China
| | - Zi-Yong Liu
- Key Laboratory of Biofuels and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology - Chinese Academy of Sciences Qingdao, China
| | - Fu-Li Li
- Key Laboratory of Biofuels and Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology - Chinese Academy of Sciences Qingdao, China ; Sinopec Fushun Research Institute of Petroleum and Petrochemicals Fushun, China
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4
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Xu M, Zhao J, Yu L, Tang I, Xue C, Yang S. Engineering Clostridium acetobutylicum with a histidine kinase knockout for enhanced n-butanol tolerance and production. Appl Microbiol Biotechnol 2015; 99:1011-22. [DOI: 10.1007/s00253-014-6249-7] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 01/07/2023]
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5
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Mearls EB, Lynd LR. The identification of four histidine kinases that influence sporulation in Clostridium thermocellum. Anaerobe 2014; 28:109-19. [PMID: 24933585 DOI: 10.1016/j.anaerobe.2014.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/29/2014] [Accepted: 06/05/2014] [Indexed: 02/03/2023]
Abstract
In this study, we sought to identify genes involved in the onset of spore formation in Clostridium thermocellum via targeted gene deletions, gene over-expression, and transcriptional analysis. We determined that three putative histidine kinases, clo1313_0286, clo1313_2735 and clo1313_1942 were positive regulators of sporulation, while a fourth kinase, clo1313_1973, acted as a negative regulator. Unlike Bacillus or other Clostridium species, the deletion of a single positively regulating kinase was sufficient to abolish sporulation in this organism. Sporulation could be restored in these asporogenous strains via overexpression of any one of the positive regulators, indicating a high level of redundancy between these kinases. In addition to having a sporulation defect, deletion of clo1313_2735 produced L-forms. Thus, this kinase may play an additional role in repressing L-form formation. This work suggests that C. thermocellum enters non-growth states based on the sensory input from multiple histidine kinases. The ability to control the development of non-growth states at the genetic level has the potential to inform strategies for improved strain development, as well as provide valuable insight into C. thermocellum biology.
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Affiliation(s)
- Elizabeth B Mearls
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA; BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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6
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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7
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Mearls EB, Izquierdo JA, Lynd LR. Formation and characterization of non-growth states in Clostridium thermocellum: spores and L-forms. BMC Microbiol 2012; 12:180. [PMID: 22897981 PMCID: PMC3438076 DOI: 10.1186/1471-2180-12-180] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 07/03/2012] [Indexed: 11/11/2022] Open
Abstract
Background Clostridium thermocellum is an anaerobic thermophilic bacterium that exhibits high levels of cellulose solublization and produces ethanol as an end product of its metabolism. Using cellulosic biomass as a feedstock for fuel production is an attractive prospect, however, growth arrest can negatively impact ethanol production by fermentative microorganisms such as C. thermocellum. Understanding conditions that lead to non-growth states in C. thermocellum can positively influence process design and culturing conditions in order to optimize ethanol production in an industrial setting. Results We report here that Clostridium thermocellum ATCC 27405 enters non-growth states in response to specific growth conditions. Non-growth states include the formation of spores and a L-form-like state in which the cells cease to grow or produce the normal end products of metabolism. Unlike other sporulating organisms, we did not observe sporulation of C. thermocellum in low carbon or nitrogen environments. However, sporulation did occur in response to transfers between soluble and insoluble substrates, resulting in approximately 7% mature spores. Exposure to oxygen caused a similar sporulation response. Starvation conditions during continuous culture did not result in spore formation, but caused the majority of cells to transition to a L-form state. Both spores and L-forms were determined to be viable. Spores exhibited enhanced survival in response to high temperature and prolonged storage compared to L-forms and vegetative cells. However, L-forms exhibited faster recovery compared to both spores and stationary phase cells when cultured in rich media. Conclusions Both spores and L-forms cease to produce ethanol, but provide other advantages for C. thermocellum including enhanced survival for spores and faster recovery for L-forms. Understanding the conditions that give rise to these two different non-growth states, and the implications that each has for enabling or enhancing C. thermocellum survival may promote the efficient cultivation of this organism and aid in its development as an industrial microorganism.
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8
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Abstract
The effects of acetone and butanol on the growth of vegetative cells and the stability of swollen-phase bright-stationary-phase cells (clostridial forms) of Clostridium acetobutylicum P262 and an autolytic deficient mutant (lyt-1) were investigated. There was little difference in the sensitivity of strain P262 and the lyt-1 mutant vegetative cells and clostridial forms to acetone. The stability of the different morphological stages was unaffected by acetone concentrations far in excess of those encountered in factory fermentations. Butanol concentrations between 7 and 16 g/liter, which are within the range obtained in industrial fermentations, increased the degeneration of strain P262 clostridial forms but had no effect on the stability of lyt-1 clostridial forms which never underwent autolysis. Vegetative cells of the lyt-1 mutant were able to grow in higher concentrations of butanol than strain P262 vegetative cells. It was concluded that there is a relationship between butanol tolerance and autolytic activity.
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Affiliation(s)
- A Van Der Westhuizen
- Department of Microbiology, University of Cape Town, Rondebosch, 7700 South Africa
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10
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Collett HJ, Woods DR, Reid SJ. Characterisation of a Transposon-induced Pleiotropic Mutant ofClostridium acetobutylicumP262. Anaerobe 1997; 3:411-21. [PMID: 16887617 DOI: 10.1006/anae.1997.0127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/1997] [Accepted: 08/29/1997] [Indexed: 11/22/2022]
Abstract
Transposon-induced metronidazole resistance was used as a selection system for the isolation of Clostridium acetobutylicum P262 mutants with altered electron transport pathways. The metronidazole resistant transconjugant of interest, mutant 3R, displayed resistance to DNA damaging agents, UV and bleomycin, and harboured a single transposon insertion within a structural gene, designated sum(susceptibility to metronidazole). The sum gene encoded a 334 amino-acid protein, with 36% identity and 57-58% similarity at the amino acid level to two archaebacterial protein sequences which appear to represent a class of uncharacterised reductase enzymes. Physiological studies of mutant 3R revealed a number of pleiotropic characteristics which included enhanced autolysin activity, increased motility, impaired clostridial cell formation, and resistance to the toxic tripeptide analogue, bialaphos. The introduction of the sum gene in multiple copies on a plasmid vector into the related strain Clostridium beijerinckii NCIMB 8052, resulted in inhibition of cell division, motility and autolysin activity. The sum gene appears to be a member of a new subgroup of activases with reducing activity, which may control a regulon affecting different stationary phase processes such as clostridial differentiation and sporulation in C. acetobutylicum P262. The metronidazole resistant phenotype of the sum mutant can be attributed to an increased capacity for DNA repair.
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Affiliation(s)
- H J Collett
- Department of Biochemistry, University of the Western Cape, Bellville, 7535, South Africa
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11
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12
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Zhou X, Traxler R. Enhanced butanol production and reduced autolysin activity after chloramphenicol treatment of Clostridium acetobutylicum ATCC 824. Appl Microbiol Biotechnol 1992. [DOI: 10.1007/bf00210980] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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14
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Abstract
The lyc gene, encoding an autolytic lysozyme from Clostridium acetobutylicum ATCC824, has been cloned. The nucleotide sequence of the lyc gene has been determined and found to encode a protein of 324 amino acids (aa) with a deduced Mr of 34,939. The lyc gene is preceded by two open reading frames with unknown functions, suggesting that this gene is part of an operon. Comparison between the deduced aa sequence of the lyc gene and the directly determined N-terminal sequence of the extracellular clostridial lysozyme suggests that the enzyme is synthesized without a cleavable signal peptide. Moreover, the comparative analyses between the clostridial lysozyme and other known cell-wall lytic enzymes revealed a significant similarity with the N-terminal portion of the lysozymes of Streptomyces globisporus, the fungus Chalaropsis, the Lactobacillus bulgaricus bacteriophage mv1, and the Streptococcus pneumoniae bacteriophages of the Cp family (CPL lysozymes). In addition, the analyses showed that the C-terminal half of the clostridial lysozyme was homologous to the N-terminal domain of the muramoyl-pentapeptide-carboxypeptidase of Streptomyces albus, suggesting a role in substrate binding. The existence of five putative repeated motifs in the C-terminal region of the autolytic lysozyme suggests that this region could play a role in the recognition of the polymeric substrate.
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Affiliation(s)
- C Croux
- Unidad de Genética Bacteriana, Centro de Investigaciones Biológicas, Madrid, Spain
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15
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16
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Abstract
Renewed interest in the acetone-butanol-ethanol (ABE) fermentation as a route for industrial production of butanol has been evident since the oil crisis of the 1970s. The present review includes an historical recap of the traditional industrial process and culturing practices useful in maintaining viable solvent-producing cultures, and then summarizes new and exciting research on the physiology and genetics of the microorganisms as well as process design. Most of these reports relate to improvements in solvent yield and the overall process, since traditional production is not efficient under present economic conditions. Conclusions are then made on future developments necessary for the establishment of an economically viable industrial process.
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Affiliation(s)
- G M Awang
- Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon, Canada
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17
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Junelles A, Janati-idrissi R, El Kanouni A, Petitdemange H, Gay R. Acetone-butanol fermentation by mutants selected for resistance to acetate and butyrate halogen analogues. Biotechnol Lett 1987; 9:175-8. [DOI: 10.1007/bf01024559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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19
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Usdin KP, Zappe H, Jones DT, Woods DR. Cloning, Expression, and Purification of Glutamine Synthetase from
Clostridium acetobutylicum. Appl Environ Microbiol 1986; 52:413-9. [PMID: 16347143 PMCID: PMC203548 DOI: 10.1128/aem.52.3.413-419.1986] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A glutamine synthetase (GS) gene,
glnA
, from the gram-positive obligate anaerobe
Clostridium acetobutylicum
was cloned on recombinant plasmid pHZ200 and enabled
Escherichia coli glnA
deletion mutants to utilize (NH
4
)
2
SO
4
as a sole source of nitrogen. The cloned
C. acetobutylicum
gene was expressed from a regulatory region contained within the cloned DNA fragment.
glnA
expression was subject to nitrogen regulation in
E. coli
. This cloned
glnA
DNA did not enable an
E. coli glnA ntrB ntrC
deletion mutant to utilize arginine or low levels of glutamine as sole nitrogen sources, and failed to activate histidase activity in this strain which contained the
Klebsiella aerogenes hut
operon. The GS produced by pHZ200 was purified and had an apparent subunit molecular weight of approximately 59,000. There was no DNA or protein homology between the cloned
C. acetobutylicum glnA
gene and GS and the corresponding gene and GS from
E. coli
. The
C. acetobutylicum
GS was inhibited by Mg
2+
in the γ-glutamyl transferase assay, but there was no evidence that the GS was adenylylated.
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Affiliation(s)
- K P Usdin
- Department of Microbiology, University of Cape Town, Rondebosch 7700, South Africa
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21
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Dürre P, Kuhn A, Gottschalk G. Treatment with allyl alcohol selects specifically for mutants ofClostridium acetobutylicumdefective in butanol synthesis. FEMS Microbiol Lett 1986. [DOI: 10.1111/j.1574-6968.1986.tb01670.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Ferras E, Minier M, Goma G. Acetonobutylic fermentation: Improvement of performances by coupling continuous fermentation and ultrafiltration. Biotechnol Bioeng 1986; 28:523-33. [DOI: 10.1002/bit.260280408] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Rogers P. Genetics and Biochemistry of Clostridium Relevant to Development of Fermentation Processes. Advances in Applied Microbiology Volume 31. Elsevier; 1986. pp. 1-60. [DOI: 10.1016/s0065-2164(08)70438-6] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Largier ST, Long S, Santangelo JD, Jones DT, Woods DR. Immobilized
Clostridium acetobutylicum
P262 Mutants for Solvent Production. Appl Environ Microbiol 1985; 50:477-81. [PMID: 16346864 PMCID: PMC238645 DOI: 10.1128/aem.50.2.477-481.1985] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The production of acetone, butanol, and ethanol by two immobilized, sporulation-deficient
(spo) Clostridium acetobutylicum
P262 mutants which were held in the solventogenic phase was investigated. The
spoA2
mutant, which was an early-sporulation mutant and did not form a forespore septum, produced higher solvent yields than did the
spoB
mutant which was a late-sporulation mutant and was blocked at a stage after forespore septum formation. The
spoA2
mutant was also granulose and capsule negative. In a conventional batch fermentation, the wild-type strain produced 15.44 g of solvents per liter after 50 h at a productivity of 7.41 g of solvents per liter per day. The
spoA2
mutant produced 15.42 g of solvents per liter at a productivity of 72.4 g of solvents per liter per day, with a retention time of 2.4 h in a continuous immobilized cell system employing a fluidized bed reactor. This represents a major advance, since the immobilization of wild-type cells showed similar increases in productivity but a ca. fivefold reduction in final product concentrations.
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Affiliation(s)
- S T Largier
- Department of Microbiology, University of Cape Town, Rondebosch, 7700, South Africa
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26
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Abstract
Mutagenesis of the obligate anaerobe Clostridium acetobutylicum was best accomplished using agents (e.g. ethyl methane sulphonate or N-methyl-N'-nitro-N-nitrosoguanidine) which are believed to act by a direct mutagenic mechanism. Other agents (e.g. u.v. radiation) whose effectiveness relies on misrepair of damaged DNA via an error-prone pathway, were poor mutagens of this organism. Procedures are described which readily yielded a variety of auxotrophic and other useful mutant strains of Cl. acetobutylicum and related saccharolytic clostridia.
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28
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Abstract
Clostridium perfringens 11268 CDR (Rifr Tcs), the strain transformed in our experiments, was generated by curing a spontaneous, rifampicin-resistant mutant of C. perfringens 11268 (Rifr Tcr). High-temperature growth yielded tetracycline-sensitive, rifampicin-resistant cells which no longer contained pCW3, a 42.8-kilobase plasmid. The tetracycline-sensitive, rod-shaped cell was then converted to an L-phase variant by growth in the presence of penicillin G (10 micrograms/ml) and 0.4 M sucrose. After several passages, the antibiotic was removed from the medium, and cells continued to grow as L-phase variants. Another large plasmid, pJU124 (38.8 kilobases), which confers tetracycline resistance, was used for transformation. Transformation of L-phase variants of C. perfringens 11268 CDR (Rifr Tcs) was mediated by polyethylene glycol. Transformation frequency is a nonlinear function of DNA concentration. Restriction analysis showed that the plasmid isolated from the transformants was identical to that supplied. Stable L-phase variants do not revert to rod-shaped cells, but autoplasts can be both transformed and reverted.
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Abstract
A defined minimal sporulation medium for
Clostridium acetobutylicum
P262, which produces high levels of solvents, is described. The overall sporulation sequence was similar to that of other endospore-forming bacteria. However, we observed a presporulation stage, during which swollen phase-bright cells which contained large amounts of granulose formed. During sporulation, the initiation of spore coat formation occurred before the onset of cortex formation. Other
Clostridium
strains tested showed marked variations in ability to grow and sporulate in various minimal media.
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Affiliation(s)
- S Long
- Department of Microbiology, University of Cape Town, Rondebosch, 7700, South Africa
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30
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31
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Jones DT, van der Westhuizen A, Long S, Allcock ER, Reid SJ, Woods DR. Solvent Production and Morphological Changes in
Clostridium acetobutylicum. Appl Environ Microbiol 1982; 43:1434-9. [PMID: 16346038 PMCID: PMC244251 DOI: 10.1128/aem.43.6.1434-1439.1982] [Citation(s) in RCA: 131] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The morphological and cytological changes which occurred in
Clostridium acetobutylicum
P262 during the production of acetone, butanol, and ethanol in an industrial fermentation medium were identified and correlated with the growth and physiological changes. The swollen, cigar-shaped clostridial forms were involved in the conversion of acids to neutral solvents, and there was a correlation between the number of clostridial forms and the production of solvents. Sporulation mutants which were unable to form clostridial stages (
cls
mutants) did not produce solvents. Oligosporogenous mutants which showed reduced clostridial stage formation produced intermediate levels of solvents. Sporulation mutants blocked after the clostridial stage, which were unable to form mature spores (
spo
mutants), produced normal levels of solvents.
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Affiliation(s)
- D T Jones
- Department of Microbiology, University of Cape Town, Rondebosch 7700, South Africa
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