| a technique for predicting the solvent-producing ability of clostridium acetobutylicum. | changes in colony morphology were associated with the degeneration of solvent-producing strains of clostridium acetobutylicum. the most efficient solvent-producing strains gave rise exclusively to colonies with dense centers containing large numbers of spores. many outgrowths of various morphologies developed from the perimeter of such colonies after several days of incubation. the most degenerate cultures did not produce solvents and gave rise to large diffuse colonies that did not contain spor ... | 1987 | 16347466 |
| characterisation of a glucose phosphotransferase system in clostridium acetobutylicum atcc 824. | the transport of glucose by the solventogenic anaerobe clostridium acetobutylicum was investigated. glucose phosphoenolpyruvate (pep)-dependent phosphotransferase system (pts) activity was detected in extracts prepared from cultures grown on glucose and extract fractionation revealed that both soluble and membrane components are required for activity. glucose pts activity was inhibited by the analogue methyl alpha-glucoside, indicating that the pts enzyme ii belongs to the glucose-glucoside (glc ... | 2007 | 17096120 |
| effect of butanol challenge and temperature on lipid composition and membrane fluidity of butanol-tolerant clostridium acetobutylicum. | the effect of butanol challenge (0, 1.0, 1.5% [vol/vol]) and growth temperature (22, 37, 42 degrees c) on the membrane composition and fluidity of clostridium acetobutylicum atcc 824 and a butanol-tolerant mutant, sa-2, was examined in chemically defined medium. growth of strain atcc 824 into the stationary phase coincided with a gradual increase in the percent saturated to percent unsaturated (su) fatty acid ratio. when challenged with butanol at 22 and 37 degrees c, atcc 824 demonstrated an im ... | 1987 | 16347502 |
| novel substrate specificity of glutathione synthesis enzymes from streptococcus agalactiae and clostridium acetobutylicum. | glutathione (gsh) is synthesized by gamma-glutamylcysteine synthetase (gamma-gcs) and glutathione synthetase (gs) in living organisms. recently, bifunctional fusion protein, termed gamma-gcs-gs catalyzing both gamma-gcs and gs reactions from gram-positive firmicutes streptococcus agalactiae, has been reported. we revealed that in the gamma-gcs activity, s. agalactiae gamma-gcs-gs had different substrate specificities from those of escherichia coli gamma-gcs. furthermore, s. agalactiae gamma-gcs- ... | 2007 | 17123467 |
| antimicrobial activity of different proteins and their fragments from bacillus thuringiensis parasporal crystals against clostridia and archaea. | proteins of parasporal crystals (cry proteins) from entomopathogenic bacterium bacillus thuringiensis (subspecies kurstaki, galleriae, tenebrionis) as well as some fragments of these proteins, obtained by limited proteolysis, are capable of antimicrobial action against anaerobic bacteria and archaea-clostridium butyricum, clostridium acetobutylicum and methanosarcina barkeri. the mics are 45-150 microg/ml. electron microscopy showed that lysis of m. barkeri cells in the presence of 49kda fragmen ... | 2007 | 17126041 |
| analysis of the mechanism and regulation of lactose transport and metabolism in clostridium acetobutylicum atcc 824. | although the acetone-butanol-ethanol fermentation of clostridium acetobutylicum is currently uneconomic, the ability of the bacterium to metabolize a wide range of carbohydrates offers the potential for revival based on the use of cheap, low-grade substrates. we have investigated the uptake and metabolism of lactose, the major sugar in industrial whey waste, by c. acetobutylicum atcc 824. lactose is taken up via a phosphoenolpyruvate-dependent phosphotransferase system (pts) comprising both solu ... | 2007 | 17209069 |
| heat-shock protein hspa mimics the function of phasins sensu stricto in recombinant strains of escherichia coli accumulating polythioesters or polyhydroxyalkanoates. | polyhydroxyalkanoic acids (phas) are synthesized by unspecific pha synthases and deposited as energy and carbon storage granules in the cytoplasm of many prokaryotes. the number and size of the granules depend on the presence of phasins which are amphiphilic structural proteins occurring at the granule surface. recently, it was shown that polythioesters (ptes) are also synthesized by pha synthases. to increase the yield of these polymers, the role of recombinant phasins was analysed in an artifi ... | 2007 | 17259608 |
| spoiie regulates sporulation but does not directly affect solventogenesis in clostridium acetobutylicum atcc 824. | using gene expression reporter vectors, we examined the activity of the spoiie promoter in wild-type and spo0a-deleted strains of clostridium acetobutylicum atcc 824. in wild-type cells, the spoiie promoter is active in a transient manner during late solventogenesis, but in strain sko1, where the sporulation initiator spo0a is disrupted, no spoiie promoter activity is detectable at any stage of growth. strains 824(pmspo) and 824(passpo) were created to overexpress spoiie and to decrease spoiie e ... | 2005 | 15743939 |
| functional organization of a single nif cluster in the mesophilic archaeon methanosarcina mazei strain gö1. | the mesophilic methanogenic archaeon methanosarcina mazei strain gö1 is able to utilize molecular nitrogen (n2) as its sole nitrogen source. we have identified and characterized a single nitrogen fixation (nif) gene cluster in m. mazei gö1 with an approximate length of 9 kbp. sequence analysis revealed seven genes with sequence similarities to nifh, nifi1, nifi2, nifd, nifk, nife and nifn, similar to other diazotrophic methanogens and certain bacteria such as clostridium acetobutylicum, with the ... | 2002 | 15803652 |
| proteome analysis and comparison of clostridium acetobutylicum atcc 824 and spo0a strain variants. | the proteomic profiles of several clostridium acetobutylicum strains were compared by two-dimensional gel electrophoresis and mass spectroscopy. the proteomic profile of c. acetobutylicum wild type strain atcc 824 with and without a commonly used control plasmid and with a spo0a overexpression plasmid pmspoa was compared. a total of 2,081 protein spots were analyzed; 23 proteins were chosen to be identified of which 18 were unique and 5 were proteins located in more than one location. the protei ... | 2006 | 16308714 |
| a general framework for designing and validating oligomer-based dna microarrays and its application to clostridium acetobutylicum. | while dna microarray analysis is widely accepted as an essential tool for modern biology, its use still eludes many researchers for several reasons, especially when microarrays are not commercially available. in that case, the design, construction, and use of microarrays for a sequenced organism constitute substantial, time-consuming, and expensive tasks. recently, it has become possible to construct custom microarrays using industrial manufacturing processes, which offer several advantages, inc ... | 2007 | 17526797 |
| the clostron: a universal gene knock-out system for the genus clostridium. | progress in exploiting clostridial genome information has been severely impeded by a general lack of effective methods for the directed inactivation of specific genes. those few mutants that have been generated have been almost exclusively derived by single crossover integration of a replication-deficient or defective plasmid by homologous recombination. the mutants created are therefore unstable. here we have adapted a mutagenesis system based on the mobile group ii intron from the ltrb gene of ... | 2007 | 17658189 |
| complete activity profile of clostridium acetobutylicum [fefe]-hydrogenase and kinetic parameters for endogenous redox partners. | in clostridium acetobutylicum, [fefe]-hydrogenase is involved in hydrogen production in vivo by transferring electrons from physiological electron donors, ferredoxin and flavodoxin, to protons. in this report, by modifications of the purification procedure, the specific activity of the enzyme has been improved and its complete catalytic profile in hydrogen evolution, hydrogen uptake, proton/deuterium exchange and para-h2/ortho-h2 conversion has been determined. the major ferredoxin expressed in ... | 2007 | 17681007 |
| cytochrome p450 monooxygenase from clostridium acetobutylicum: a new alpha-fatty acid hydroxylase. | cytochrome p450 monooxygenase from the anaerobic microorganism clostridium acetobutylicum (cyp152a2) has been produced in escherichia coli. cyp152a2 was shown to bind a broad range of saturated and unsaturated fatty acids and corresponding methyl esters and demonstrated a high peroxygenase activity of up to 200min(-1) with myristic acid. although a high concentration of hydrogen peroxide of 200microm was necessary for high activities of the enzyme, it led to a fast enzyme inactivation within 2-4 ... | 2007 | 17706598 |
| adaptive responses to oxygen stress in obligatory anaerobes clostridium acetobutylicum and clostridium aminovalericum. | clostridium acetobutylicum and clostridium aminovalericum, both obligatory anaerobes, grow normally after growth conditions are changed from anoxic to microoxic, where the cells consume oxygen proficiently. in c. aminovalericum, a gene encoding a previously characterized h2o-forming nadh oxidase, designated noxa, was cloned and sequenced. the expression of noxa was strongly upregulated within 10 min after the growth conditions were altered to a microoxic state, indicating that c. aminovalericum ... | 2005 | 16332833 |
| biobutanol: an attractive biofuel. | biofuels are an attractive means to prevent a further increase of carbon dioxide emissions. currently, gasoline is blended with ethanol at various percentages. however, butanol has several advantages over ethanol, such as higher energy content, lower water absorption, better blending ability, and use in conventional combustion engines without modification. like ethanol, it can be produced fermentatively or petrochemically. current crude oil prices render the biotechnological process economic aga ... | 2007 | 17924389 |
| solvent production and morphological changes in clostridium acetobutylicum. | 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 unabl ... | 1982 | 16346038 |
| targeted gene disruption by use of a group ii intron (targetron) vector in clostridium acetobutylicum. | | 2007 | 17971808 |
| autolytic activity and butanol tolerance of clostridium acetobutylicum. | 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 ... | 1982 | 16346145 |
| transformation of clostridium acetobutylicum protoplasts with bacteriophage dna. | techniques for the transformation of clostridium acetobutylicum protoplasts with bacteriophage dna are described. transformation required regeneration of protoplasts and a 2-h eclipse period. | 1983 | 16346174 |
| characterization of the cellulolytic and hydrogen-producing activities of six mesophilic clostridium species. | to characterize cellulolytic, hydrogen-producing clostridia on a comparable basis. | 2007 | 18045409 |
| expression of clostridium acetobutylicum butanol synthetic genes in escherichia coli. | a recombinant butanol pathway composed of clostridium acetobutylicum atcc 824 genes, thil, hbd, crt, bcd-etfb-etfa, and adhe1 (or adhe) coding for acetyl-coa acetyltransferase (thl), beta-hydroxybutyryl-coa dehydrogenase (hbd), 3-hydroxybutyryl-coa dehydratase (crt), butyryl-coa dehydrogenase (bcd), butyraldehyde dehydrogenase (bydh), and butanol dehydrogenase (bdh), under the tac promoter control was constructed and was introduced into escherichia coli. the functional expression of these six en ... | 2008 | 18060402 |
| characterization of two 2[4fe4s] ferredoxins from clostridium acetobutylicum. | in vivo hydrogen production in clostridium acetobutylicum involves electron transfer between ferredoxin and [fefe]-hydrogenase. five c. acetobutylicum open reading frames were annotated as coding for putative ferredoxins. we focused our biophysical and biochemical investigations on cac0303 and cac3527, which possess the sequence signature and length of classical 2[4fe4s] clostridial ferredoxins but differ significantly in theoretical pi. after cloning, heterologous expression in e. coli followed ... | 2008 | 18074176 |
| [fefe]-hydrogenase-catalyzed h2 production in a photoelectrochemical biofuel cell. | the clostridium acetobutylicum [fefe]-hydrogenase hyda has been investigated as a hydrogen production catalyst in a photoelectrochemical biofuel cell. hydrogenase was adsorbed to pyrolytic graphite edge and carbon felt electrodes. cyclic voltammograms of the immobilized hydrogenase films reveal cathodic proton reduction and anodic hydrogen oxidation, with a catalytic bias toward hydrogen evolution. when corrected for the electrochemically active surface area, the cathodic current densities are s ... | 2008 | 18205358 |
| production of solvents by clostridium acetobutylicum cultures maintained at neutral ph. | the formation of acetone and n-butanol by clostridium acetobutylicum ncib 8052 (atcc 824) was monitored in batch culture at 35 degrees c in a glucose (2% [wt/vol]) minimal medium maintained throughout at either ph 5.0 or 7.0. at ph 5, good solvent production was obtained in the unsupplemented medium, although addition of acetate plus butyrate (10 mm each) caused solvent production to be initiated at a lower biomass concentration. at ph 7, although a purely acidogenic fermentation was maintained ... | 1984 | 16346678 |
| modulation of acetone-butanol-ethanol fermentation by carbon monoxide and organic acids. | metabolic modulation of acetone-butanol-ethanol fermentation by clostridium acetobutylicum with carbon monoxide (co) and organic acids is described. co, which is a known inhibitor of hydrogenase, was found to be effective in the concentration range of dissolved co corresponding to a co partial pressure of 0.1 to 0.2 atm. metabolic modulation by co was particularly effective when organic acids such as acetic and butyric acids were added to the fermentation as electron sinks. the uptake of organic ... | 1985 | 16346746 |
| how obligatory is anaerobiosis? | historically many bacteria have been classified as obligate anaerobes. they have been construed as wholly intolerant of oxygen, a feature that was originally ascribed to their lack of superoxide dismutases and catalases. clostridial species were regarded as classic examples. we now know that this view is quite wrong: enzymes that scavenge superoxide, hydrogen peroxide and even oxygen itself abound in anaerobes. in the current issue of molecular microbiology, hillmann et al. demonstrate that full ... | 2008 | 18363793 |
| cellulolytic activity of clostridium acetobutylicum. | clostridium acetobutylicum nrrl b527 and atcc 824 exhibited extracellular and cell-bound endoglucanase and cellobiase activities during growth in a chemically defined medium with cellobiose as the sole source of carbohydrate. for both strains, the endoglucanase was found to be mainly extracellular (70 to 90%) during growth in continuous or batch cultures with the ph maintained at 5.2, whereas the cellobiase was mainly cell associated (60 to 90%). during continuous cultivation of strain b527 with ... | 1985 | 16346847 |
| influence of external ph and fermentation products on clostridium acetobutylicum intracellular ph and cellular distribution of fermentation products. | clostridium acetobutylicum atcc 824 cells harvested from a phosphate-limited chemostat culture maintained at ph 4.5 had intracellular concentrations of acetate, butyrate, and butanol which were 13-, 7-, and 1.3-fold higher, respectively, than the corresponding extracellular concentrations. cells from a culture grown at ph 6.5 had intracellular concentrations of acetate and butyrate which were only 2.2-fold higher than the respective external concentrations. the highest intracellular concentratio ... | 1986 | 16347081 |
| crystal structure of 2-phosphosulfolactate phosphatase (comb) from clostridium acetobutylicum at 2.6 a resolution reveals a new fold with a novel active site. | | 2006 | 16927339 |
| biosynthesis of enantiopure (s)-3-hydroxybutyric acid in metabolically engineered escherichia coli. | a biosynthetic pathway for the production of (s)-3-hydroxybutyric acid (s3hb) from glucose was established in recombinant escherichia coli by introducing the beta-ketothiolase gene from ralstonia eutropha h16, the (s)-3-hydroxybutyryl-coa dehydrogenase gene from r. eutropha h16, or clostridium acetobutylicum atcc824, and the 3-hydroxyisobutyryl-coa hydrolase gene from bacillus cereus atcc14579. artificial operon consisting of these genes was constructed and was expressed in e. coli bl21 (de3) co ... | 2008 | 18461320 |
| [extracellular glycosyl hydrolase activity of the clostridia producing acetone, butanol, and ethanol]. | production of acetone, butanol, ethanol, acetic acid, and butyric acid by three strains of anaerobic bacteria, which we identified as clostridium acetobutylicum, was studied. the yield of acetone and alcohols in 6% flour medium amounted to 12.7-15 g/l with butanol constituting 51.0-55.6%. activities of these strains towards xylan, beta-glucan, carboxymethylcellulose, and crystalline and amorphous celluloses were studied. c. acertobutylicum 6, c. acetoburylicum 7, and c. acertobutylicum vkpm b-47 ... | 2008 | 18491597 |
| hydf as a scaffold protein in [fefe] hydrogenase h-cluster biosynthesis. | in an effort to determine the specific protein component(s) responsible for in vitro activation of the [fefe] hydrogenase (hyda), the individual maturation proteins hyde, hydf, and hydg from clostridium acetobutylicum were purified from heterologous expressions in escherichia coli. our results demonstrate that hydf isolated from a strain expressing all three maturation proteins is sufficient to confer hydrogenase activity to purified inactive heterologously expressed hyda (expressed in the absen ... | 2008 | 18501709 |
| the effect of ph on nitrogen supply, cell lysis, and solvent production in fermentations of clostridium acetobutylicum. | in batch fermentations of c. acetobutylicum, with 5 g/l yeast extract and 50mm glucose, the ratio of ammonium to glucose affected solvent production when the ph was left to vary uncontrolled from 4.5 to 3.65. high solvent production was observed for a low ratio. when the ph was controlled at 4.5, only acids were produced for all ratio values. at a low ammonium-to-glucose ratio, solvents were produced when the ph was controlled at 3.7. acids only were produced for a low ratio value at ph 4.0 or f ... | 1985 | 18553724 |
| isolation and some properties of a beta-d-xylosidase from clostridium acetobutylicum atcc 824. | a beta-d-xylosidase from c. acetobutylicum atcc 824 was purified by column chromatography on cm-sepharose, hydroxylapatite, phenyl sepharose, and sephadex g-200. the enzyme had an apparent molecular weight of 224,000 as estimated by gel filtration. sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the enzyme consisted of two subunits of 85,000 and one subunit of 63,000 daltons. it exhibited optimal activity at ph 6.0 to 6.5 and 45 degrees c. the enzyme had an isoelectric poin ... | 1987 | 16347313 |
| characterization of a novel ferredoxin with n-terminal extension from clostridium acetobutylicum atcc 824. | a gene (cac2657) encoding a ferredoxin (efr1) from the strictly anaerobic soil bacterium clostridium acetobutylicum was cloned and expressed in escherichia coli. the ferredoxin gene encodes a polypeptide of 27 kda that incorporates 2[4fe-4s] clusters. an extended n-terminal region of 187 amino acid (aa) residues precedes ferredoxin domain. the efr1 expressed in e. coli is a trimeric protein. the iron and sulfur content of the reconstituted protein agrees with that expected of a trimeric form of ... | 2007 | 17089149 |
| a standard operating procedure (sop) for the preparation of intra- and extracellular proteins of clostridium acetobutylicum for proteome analysis. | we report on the development of a standard operating procedure (sop) for extraction and handling of intra- and extracellular protein fractions of clostridium acetobutylicum atcc 824 for reproducible high quality two-dimensional gel electrophoresis (2-de) analyses. standardized cells from a phosphate-limited chemostat were used to evaluate different protein preparation methods. for the preparation of the secretome, a dialysis/ultrafiltration procedure resulted in higher protein yields and proved ... | 2007 | 17098314 |
| clostridium acetobutylicum mutants that produce butyraldehyde and altered quantities of solvents. | spontaneous mutants of clostridium acetobutylicum nrrl b643 that were resistant to allyl alcohol (aa) were selected and characterized. these mutants contained 10- to 100-fold reduced activities of butanol and ethanol alcohol dehydrogenase. the aa mutants formed two groups and produced no ethanol. type 1 aa mutants produced significant amounts of a new solvent, butyraldehyde, and contained normal levels of the coenzyme a-dependent butyraldehyde dehydrogenase (bad). type 2 aa mutants produced no s ... | 1987 | 16347493 |
| dynamics of genomic-library enrichment and identification of solvent tolerance genes for clostridium acetobutylicum. | a clostridium acetobutylicum atcc 824 genomic library was constructed using randomly sheared dna. library inserts conferring increased tolerance to 1-butanol were isolated using two protocols. protocol i utilized a single round of butanol challenges in batch culture, while protocol ii, which gave clearly superior outcomes, was based on the serial transfer of stationary-phase cultures into progressively higher butanol concentrations. dna microarray analysis made a high-resolution assessment of th ... | 2007 | 17337545 |
| mathematical model of a batch acetone-butanol fermentation. | a mathematical model for the batch culture of clostridium acetobutylicum was formulated using experimental data for anaerobic solvent production. the model summarizes biochemical as well as physiological aspects of growth and metabolite synthesis by the production strain. the key fermentation rates are expressed and evaluated with regard to substrate consumption and butanol end-product inhibitory effects. parametric sensitivity analysis of the batch process model was carried out, indicating the ... | 1986 | 18555322 |
| cloning and expression of a clostridium acetobutylicum alcohol dehydrogenase gene in escherichia coli. | an alcohol dehydrogenase (adh) gene from clostridium acetobutylicum was cloned on a recombinant plasmid, pcadh100. escherichia coli hb101, and an allyl alcohol-resistant mutant, hb101-adh1, containing this plasmid were unable to grow aerobically or anaerobically on agar media containing sublethal concentrations of allyl alcohol. e. coli hb101 and hb101-adh1 transformed with the plasmid pcadh100 produced increased levels of ethanol when grown anaerobically under alkaline conditions in the absence ... | 1988 | 16347579 |
| enhancement of butanol formation by clostridium acetobutylicum in the presence of decanol-oleyl alcohol mixed extractants. | extractive fermentation has been proposed to enhance the productivity of fermentations that are end product inhibited. unfortunately, good extractants for butanol, such as decanol, are toxic to clostridium acetobutylicum. the use of mixed extractants, namely, mixtures of toxic and nontoxic coextractants, was proposed to circumvent this toxicity. decanol appeared to inhibit butanol formation by c. acetobutylicum when present in a mixed extractant that also contained oleyl alcohol. however, mainte ... | 1988 | 16347676 |
| physiological events in clostridium acetobutylicum during the shift from acidogenesis to solventogenesis in continuous culture and presentation of a model for shift induction. | the ph of continuous cultures of clostridium acetobutylicum growing at ph 5.6 was allowed to decrease to 4.3 after acid production and thereby to shift the cultures from acetate and butyrate to acetone and butanol formation. several parameters were determined during the shift. an increase in the intracellular acid concentration to 440 mm was recorded. an excess of undissociated butyric acid but not of acetic acid just before the shift to solventogenesis was followed by a decline in acid producti ... | 1992 | 16348821 |
| post-transcriptional modification mapping in the clostridium acetobutylicum 16s rrna by mass spectrometry and reverse transcriptase assays. | post-transcriptional modifications in ribosomal rna are believed to fine-tune the rna functions. the present study describes the characterization of the post-transcriptional modifications in clostridium acetobutylicum 16s rrna, using high-pressure liquid chromatography (hplc) coupled to electrospray ionization mass spectrometry and reverse transcriptase assays. the combination of these techniques allowed the identification of eleven modified nucleosides, which were mapped onto the rrna sequence. ... | 2007 | 17478509 |
| preservation of potential fermentables in sweet sorghum by ensiling. | pressed and wilted samples of sweet sorghum [sorghum bicolor (l.) moench var. rio] were ensiled for periods up to 155 days. a kinetic study of the biochemical changes which occurred during ensiling showed that in wilted sorghum ensilage invert sugars and mannitol levels collectively were maintained at 65% of the original ferment able sugar content of the sorghum. the acidic environment produced by ensiling also served as a pretreatment that resulted in enhanced yields of reducing sugar when the ... | 1987 | 18581521 |
| in situ extractive fermentation of acetone and butanol. | the productivity of the acetone-butanol fermentation was increased by continuously removing acetone and butanol from the fermentation broth during fed-batch culture. whole broth containing viable cells of clostridium acetobutylicum was cycled to a karr reciprocating plate extraction column in which acetone and butanol were extracted into oleyl alcohol flowing counter-currently through the column. by continuously removing these toxic metabolites from the broth, end product inhibition was reduced, ... | 1988 | 18581574 |
| isolation of a degeneration-resistant mutant of clostridium acetobutylicum ncimb 8052. | unless periodically grown from germinated spores, clostridium acetobutylicum tends to degenerate (that is, to spontaneously lose the capacity both to produce solvents and to develop into spores). to obtain mutants that are deficient in degeneration, c. acetobutylicum ncimb 8052 was mated with enterococcus faecalis bm4110 harboring transposon tn1545. we developed a degeneration resistance assay based on a secondary effect of degeneration, the production of toxic levels of acetic and butyric acids ... | 1993 | 16349119 |
| solventogenesis in clostridium acetobutylicum fermentations related to carboxylic acid and proton concentrations. | the mechanism primarily implicated in the solventogenesis process in batch fermentations of clostridium acetobutylicum is examined in considerable detail. a variety of fermentations with or without ph control in the ph range of 3.7-6 have been carried out in order to examine which of a host of suspect parameters correlate with the initiation of solventogenesis. the parameters that did not correlate are the external (ph(0)) and intracellular (ph(i)) ph, and deltaph, and the external or intracellu ... | 1988 | 18587795 |
| biological hydrogen production by clostridium acetobutylicum in an unsaturated flow reactor. | a mesophilic unsaturated flow (trickle bed) reactor was designed and tested for h2 production via fermentation of glucose. the reactor consisted of a column packed with glass beads and inoculated with a pure culture (clostridium acetobutylicum atcc 824). a defined medium containing glucose was fed at a flow rate of 1.6 ml/min (0.096 l/h) into the capped reactor, producing a hydraulic retention time of 2.1 min. gas-phase h2 concentrations were constant, averaging 74 +/- 3% for all conditions test ... | 2006 | 16427113 |
| effects of ph and added metabolites on bioconversions by immobilized non-growing clostridium acetobutylicum. | the bioconversion activity of calcium alginate-immobilized clostridium acetobutylicum atcc 824 was investigated in a continuous reactor system utilizing a defined feed medium which did not support cell growth. the changes in biocatalytic activity with time were studied at different ph values as well as when different metabolites (butyric, acetic, and acetoacetic acids) were present in the feed stream. although the nongrowing cells were metabolically active, the product distribution was shifted f ... | 1989 | 18588169 |
| studies on inhibition of transformation of 2,4,6-trinitrotoluene catalyzed by fe-only hydrogenase from clostridium acetobutylicum. | the major enzyme in clostridium acetobutylicum atcc 824 leading to transformation of tnt has been reported to be the fe-only hydrogenase. in this study, we examine the effect of inhibitors of hydrogenase on tnt reduction by clostridial extracts. these experiments further demonstrate the major role of hydrogenase in tnt transformation. the c. acetobutylicum hydrogenase is closely related to that of c. pasteurianum; and can be fitted to the x-ray crystal structure with a root mean square deviation ... | 2006 | 16550436 |
| an o2-inducible rubrerythrin-like protein, rubperoxin, is functional as a h2o2 reductase in an obligatory anaerobe clostridium acetobutylicum. | clostridium acetobutylicum, an obligatory anaerobe, is able to grow microoxically with the accumulation of two functionally unknown o2-induced proteins identified by two-dimensional electrophoresis. one was determined to be a novel type rubrerythrin-like protein, named rubperoxin (rpr) in this study, that conserves one rubredoxin-type fe(scys)(4) site per polypeptide in the n-terminus. recombinant rubperoxin expressed in e. coli purified in its oxidized form is a dimer with optical absorption ma ... | 2007 | 17485086 |
| electrooptical measurements for monitoring metabolite fluxes in acetone-butanol-ethanol fermentations. | anisotropy of electrical polarizability in clostridium acetobutylicum cells during ph 5 controlled acetone butanol ethanol fermentations was observed. cell length was determined from the electrooptical data. mean length was determined as being 2.5 microm in the growth phase and 3.5 microm in the early stationary phase. based on the obtained frequency dispersion of polarizability anisotropy (fdpa) in the range of 190 to 2,100 khz, the switch from the acidogenic to the solventogenic phase could be ... | 2008 | 17787006 |
| metabolic engineering of clostridium acetobutylicum atcc 824 for increased solvent production by enhancement of acetone formation enzyme activities using a synthetic acetone operon. | the ability to genetically alter the product-formation capabilities of clostridium acetobutylicum is necessary for continued progress toward industrial production of the solvents butanol and acetone by fermentation. batch fermentations at ph 4.5, 5.5, or 6.5 were conducted using c. acetobutylicum atcc 824 (pfnk6). plasmid pfnk6 contains a synthetic operon (the "ace operon") in which the three homologous acetone-formation genas (adc, ctfa, and ctfb) are transcribed from the adc promoter. the corr ... | 1993 | 18613233 |
| engineered synthetic pathway for isopropanol production in escherichia coli. | a synthetic pathway was engineered in escherichia coli to produce isopropanol by expressing various combinations of genes from clostridium acetobutylicum atcc 824, e. coli k-12 mg1655, clostridium beijerinckii nrrl b593, and thermoanaerobacter brockii htd4. the strain with the combination of c. acetobutylicum thl (acetyl-coenzyme a [coa] acetyltransferase), e. coli atoad (acetoacetyl-coa transferase), c. acetobutylicum adc (acetoacetate decarboxylase), and c. beijerinckii adh (secondary alcohol ... | 2007 | 17933911 |
| enhanced acetone-butanol fermentation using repeated fed-batch operation coupled with cell recycle by membrane and simultaneous removal of inhibitory products by adsorption. | a novel acetone-butanol production process was developed which integrates a repeated fed-batch fermentation with continuous product removal and cell recycle. the inhibitory product concentrations of the fermentation by clostridium acetobutylicum were reduced by the simultaneous extraction process using polyvinylpyridine (pvp) as an adsorbent. because of the reduced inhibition effect, a higher specific cell growth rate and thus a higher product formation rate was achieved. the cell recycle using ... | 1995 | 18623420 |
| modulation of metabolism of clostridium acetobutylicum grown in chemostat culture in a three-electrode potentiostatic system with methyl viologen as electron carrier. | the metabolism of clostridium acetobutylicum was manipulated in chemostat culture at ph 5 and 6.5 in a three-electrode potentiostatic system with methyl viologen (mv) as the electron carrier. when a constant potential was applied at ph 5, the broth redox potential continuously decreased and, simultaneously, a high increase in the reduced mv concentration (mv(+.)) and the specific rate of butanol production was observed while butyric acid was taken up. a linear relationship was reported between t ... | 1996 | 18624366 |
| the transcriptional program underlying the physiology of clostridial sporulation. | clostridia are ancient soil organisms of major importance to human and animal health and physiology, cellulose degradation, and the production of biofuels from renewable resources. elucidation of their sporulation program is critical for understanding important clostridial programs pertaining to their physiology and their industrial or environmental applications. | 2008 | 18631379 |
| the two-component system phopr of clostridium acetobutylicum is involved in phosphate-dependent gene regulation. | the phopr gene locus of clostridium acetobutylicum atcc 824 comprises two genes, phop and phor. deduced proteins are predicted to represent a response regulator and sensor kinase of a phosphate-dependent two-component regulatory system. we analyzed the expression patterns of phopr in p(i)-limited chemostat cultures and in response to p(i) pulses. a basic transcription level under high-phosphate conditions was shown, and a significant increase in mrna transcript levels was found when external p(i ... | 2008 | 18689481 |
| metabolic engineering of the non-sporulating, non-solventogenic clostridium acetobutylicum strain m5 to produce butanol without acetone demonstrate the robustness of the acid-formation pathways and the importance of the electron balance. | the primary alcohol/aldehyde dehydrogenase (coded by the aad gene) is responsible for butanol formation in clostridium acetobutylicum. we complemented the non-sporulating, non-solvent-producing c. acetobutylicum m5 strain (which has lost the psol1 megaplasmid containing aad and the acetone-formation genes) with aad expressed from the phosphotransbutyrylase promoter and restored butanol production to wild type levels. because no acetone was produced, no acids (acetate or butyrate) were re-assimil ... | 2008 | 18725313 |
| production of isopropanol by metabolically engineered escherichia coli. | a genetically engineered strain of escherichia coli jm109 harboring the isopropanol-producing pathway consisting of five genes encoding four enzymes, thiolase, coenzyme a (coa) transferase, acetoacetate decarboxylase from clostridium acetobutylicum atcc 824, and primary-secondary alcohol dehydrogenase from c. beijerinckii nrrl b593, produced up to 227 mm of isopropanol from glucose under aerobic fed-batch culture conditions. acetate production by the engineered strain was approximately one sixth ... | 2008 | 17987288 |
| desulfoferrodoxin of clostridium acetobutylicum functions as a superoxide reductase. | desulfoferrodoxin (cac2450) of clostridium acetobutylicum was purified after overexpression in e. coli. in an in vitro assay the enzyme exhibited superoxide reductase activity with rubredoxin (cac2778) of c. acetobutylicum as the proximal electron donor. rubredoxin was reduced by ferredoxin:nadp(+) reductase from spinach and nadph. the superoxide anions, generated from dissolved oxygen using xanthine and xanthine oxidase, were reduced to hydrogen peroxide. thus, we assume that desulfoferrodoxin ... | 2007 | 18005665 |
| insights in metabolism and toxin production from the complete genome sequence of clostridium tetani. | the decryption of prokaryotic genome sequences progresses rapidly and provides the scientific community with an enormous amount of information. clostridial genome sequencing projects have been finished only recently, starting with the genome of the solvent-producing clostridium acetobutylicum in 2001. a lot of attention has been devoted to the genomes of pathogenic clostridia. in 2002, the genome sequence of c. perfringens, the causative agent of gas gangrene, has been released. currently in the ... | 2004 | 16701501 |
| characterisation of a transposon-induced pleiotropic mutant of clostridium acetobutylicum p262. | 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 57-5 ... | 1997 | 16887617 |
| s-box and t-box riboswitches and antisense rna control a sulfur metabolic operon of clostridium acetobutylicum. | the ubigmccba operon of clostridium acetobutylicum is involved in methionine to cysteine conversion. we showed that its expression is controlled by a complex regulatory system combining several rna-based mechanisms. two functional convergent promoters associated with transcriptional antitermination systems, a cysteine-specific t-box and an s-box riboswitch, are located upstream of and downstream from the ubig operon, respectively. several antisense rnas were synthesized from the downstream s-box ... | 2008 | 18812398 |
| importance of agitation in acetone-butanol fermentation. | the specific rates of anaerobic solvent production by clostridium acetobutylicum increased with increasing fermentor impeller speed from 190 to 340 rpm (n(re) = 3.93 x 10(4)). the maximum values were 5.54, 3.85, and 0.8 mmol/h . g cell for butanol, acetone, and ethanol, respectively. corresponding rates for respective gases produced were 11.60 and 15.88 mmol/h . g cell for h(2) and co(2). further increases in agitation speed resulted in generally decreasing specific production rates to the point ... | 1985 | 18553818 |
| replacing escherichia coli nad-dependent glyceraldehyde 3-phosphate dehydrogenase (gapdh) with a nadp-dependent enzyme from clostridium acetobutylicum facilitates nadph dependent pathways. | reactions requiring reducing equivalents, nad(p)h, are of enormous importance for the synthesis of industrially valuable compounds such as carotenoids, polymers, antibiotics and chiral alcohols among others. the use of whole-cell biocatalysis can reduce process cost by acting as catalyst and cofactor regenerator at the same time; however, product yields might be limited by cofactor availability within the cell. thus, our study focussed on the genetic manipulation of a whole-cell system by modify ... | 2008 | 18852061 |
| saccharification of concentrated brewing bagasse slurries with dilute sulfuric acid for producing acetone-butanol by clostridium acetobutylicum. | a comprehensive kinetic study of the acid hydrolysis of concentrated brewing bagasse slurries was performed. the use of the simple series reaction model was found to be suitable when a "heterogeneous correction" (pseudosubstrate-inhibition) is taken into account in slurries with low liquid-to-biomass ratios. rate constants are shown to be dependent not only on temperature and acid concentration but essentially also on the initial biomass concentration. actual rate constants, activation energies, ... | 1986 | 18553872 |
| the acetone butanol fermentation on glucose and xylose. i. regulation and kinetics in batch cultures. | the kinetics in batch culture of the acetone butanol fermentation by clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. the fastest initial growth and transition from an acid to a solvent metabolism occurs on glucose, with a final 62 g/l glucose conversion. on xylose, an initial slower growth rate and a longer metabolic transition result in higher cellular and acids concentration, thus in a level of fermented sugar limited to 47 g/l. batch fermentations on mi ... | 1986 | 18555310 |
| reductive dioxygen scavenging by flavo-diiron proteins of clostridium acetobutylicum. | two flavo-diiron proteins (fdps), fpra1 and fpra2, are up-regulated when the strictly anaerobic solvent producer, clostridium acetobutylicum, is exposed to dioxygen. these two fdps were purified following heterologous overexpression in escherichia coli as n-terminal strep-tag fusion proteins. the recombinant fpra1 and fpra2 were found to be homodimeric and homotetrameric, respectively, and both fdps functioned as terminal components of nadh oxidases (nadh:o(2) oxidoreductases) when using c. acet ... | 2009 | 19084524 |
| characterization of the posttranscriptional modifications in legionella pneumophila small-subunit ribosomal rna. | it is generally accepted that posttranscriptional modifications in rna play a role in the fine-tuning of rna function and the maintenance of rna structure. this article describes the characterization of the posttranscriptional modifications in legionella pneumophila 16s rrna by mass spectrometry and reverse transcriptase assays. eight modified nucleotides were identified and mapped in the 16s rrna sequence. situation of these data in relation to general 16s rrna modification patterns shows that ... | 2008 | 19089822 |
| pathway for h2o2 and o2 detoxification in clostridium acetobutylicum. | an unusual non-haem diiron protein, reverse rubrerythrin (revrbr), is known to be massively upregulated in response to oxidative stress in the strictly anaerobic bacterium clostridium acetobutylicum. in the present study both in vivo and in vitro results demonstrate an h2o2 and o2 detoxification pathway in c. acetobutylicum involving revrbr, rubredoxin (rd) and nadh : rubredoxin oxidoreductase (nror). revrbr exhibited both nadh peroxidase (nadh : h2o2 oxidoreductase) and nadh oxidase (nadh : o2 ... | 2009 | 19118342 |
| o2 and reactive oxygen species detoxification complex, composed of o2-responsive nadh:rubredoxin oxidoreductase-flavoprotein a2-desulfoferrodoxin operon enzymes, rubperoxin, and rubredoxin, in clostridium acetobutylicum. | clostridium acetobutylicum, an obligate anaerobe, grows normally under continuous-o(2)-flow culture conditions, where the cells consume o(2) proficiently. an o(2)-responsive nadh:rubredoxin oxidoreductase operon composed of three genes (nror, fpra2, and dsr), encoding nror, functionally uncharacterized flavoprotein a2 (fpra2), and the predicted superoxide reductase desulfoferrodoxin (dsr), has been proposed to participate in defense against o(2) stress. to functionally characterize these protein ... | 2009 | 19124587 |
| sporulation and enterotoxin (cpe) synthesis are controlled by the sporulation-specific sigma factors sige and sigk in clostridium perfringens. | clostridium perfringens is the third most frequent cause of bacterial food poisoning annually in the united states. ingested c. perfringens vegetative cells sporulate in the intestinal tract and produce an enterotoxin (cpe) that is responsible for the symptoms of acute food poisoning. studies of bacillus subtilis have shown that gene expression during sporulation is compartmentalized, with different genes expressed in the mother cell and the forespore. the cell-specific rna polymerase sigma fact ... | 2009 | 19201796 |
| [quantitative monitoring the concentration changes of organic acids in fermentation process of clostridium acetobutylicum using capillary ion electrophoresis]. | a method for monitoring the concentration changes of organic acids in the fermentation process of clostridium acetobutylicum by capillary ion electrophoresis has been developed. in this study, 4-methoxybenzoic acid was used as the background electrolyte for the indirect ultraviolet detection, and cetyltrimethylammonium chloride (ctac) was employed as the electroosmotic flow modifier. the sample of fermentation was simply treated by centrifugation and dilution. the optimal conditions for the sepa ... | 2008 | 19253539 |
| the acetone butanol fermentation on glucose and xylose. ii. regulation and kinetics in fed-batch cultures. | the kinetics in fed-batch cultures of acetone butanol fermentation by clostridium acetobutylicum is compared on glucose, xylose, and mixtures of both sugars. the final conversion yield of sugars into solvents always increases with the sugar feeding rate. at low feeding rates, the sugar concentration in the medium becomes limiting, which results in a slower cellular growth, a slower metabolic transition from an acid to a solvent fermentation and, thus, a higher accumulation of acids. it is only a ... | 1986 | 18555311 |
| the release of fermentable carbohydrate from peat by steam explosion and its use in the microbial production of solvents. | steam treatment of peat at 200 degrees c for 3 min, followed by instantaneous decompression (steam explosion), solubilized up to 28% of the dry matter. seventy-five percent of the solubilized material was carbohydrate, 33% of which was composed of mono- and disaccharides, including galactose, glucose, xylose, mannose, arabinose, and cellobiose, in order of decreasing concentration. the solubilized materials served as the sole source of carbohydrate for growth and solvent production by clostridiu ... | 1986 | 18555312 |
| engineering alternative butanol production platforms in heterologous bacteria. | alternative microbial hosts have been engineered as biocatalysts for butanol biosynthesis. the butanol synthetic pathway of clostridium acetobutylicum was first re-constructed in escherichia coli to establish a baseline for comparison to other hosts. whereas polycistronic expression of the pathway genes resulted in the production of 34 mg/l butanol, individual expression of pathway genes elevated titers to 200 mg/l. improved titers were achieved by co-expression of saccharomyces cerevisiae forma ... | 2009 | 19464384 |
| systems analysis of the culture physiology in acetone-butanol fermentation. | the pronounced differences in performance of a strain of clostridium acetobutylicum atcc 824 were analyzed by the method of systems analysis. the mechanism for cellular transport of substrate (glucose), solvents, and acids was studied and mathematically formulated. the systems analysis approach in the treatment of data from culture experiments pointed out the cell membrane malfunction indicated by its altered permeability and reflected in the altered number of active sugar transport sites. exper ... | 1986 | 18561223 |
| ammonium acetate enhances solvent production by clostridium acetobutylicum ea 2018 using cassava as a fermentation medium. | cassava, due to its high starch content and low cost, is a promising candidate substrate for large-scale fermentation processes aimed at producing the solvents acetone, butanol and ethanol (abe). however, the solvent yield from the fermentation of cassava reaches only 60% of that achieved by fermenting corn. we have found that the addition of ammonium acetate (ch(3)coonh(4)) to the cassava medium significantly promotes solvent production from cassava fermented by clostridium acetobutylicum ea 20 ... | 2009 | 19543929 |
| construction of a synthetic ydbk-dependent pyruvate:h2 pathway in escherichia coli bl21(de3). | a synthetic pyruvate:h(2) pathway was constructed in escherichia coli bl21(de3) by co-expression of six proteins: e. coli ydbk, clostridium pasteurianum [4fe-4s]-ferredoxin, and clostridium acetobutylicum hydf, hyde, hydg, and hyda. the effect of cofactor addition and host strain on h(2) yield and fermentation product accumulation was studied, together with in vitro reconstitution of the entire pathway. the deletion of iscr and/or the addition of thiamine pyrophosphate to the medium enhanced the ... | 2009 | 19558967 |
| disruption of the acetoacetate decarboxylase gene in solvent-producing clostridium acetobutylicum increases the butanol ratio. | a possible way to improve the economic efficacy of acetone-butanol-ethanol fermentation is to increase the butanol ratio by eliminating the production of other by-products, such as acetone. the acetoacetate decarboxylase gene (adc) in the hyperbutanol-producing industrial strain clostridium acetobutylicum ea 2018 was disrupted using targetron technology. the butanol ratio increased from 70% to 80.05%, with acetone production reduced to approximately 0.21 g/l in the adc-disrupted mutant (2018adc) ... | 2009 | 19560551 |
| the role of perr in o2-affected gene expression of clostridium acetobutylicum. | in the strict anaerobe clostridium acetobutylicum, a perr-homologous protein has recently been identified as being a key repressor of a reductive machinery for the scavenging of reactive oxygen species and molecular o(2). in the absence of perr, the full derepression of its regulon resulted in increased resistance to oxidative stress and nearly full tolerance of an aerobic environment. in the present study, the complementation of a bacillus subtilis perr mutant confirmed that the homologous prot ... | 2009 | 19648241 |
| improvement of xylose utilization in clostridium acetobutylicum via expression of the tala gene encoding transaldolase from escherichia coli. | clostridium acetobutylicum atcc 824 was metabolically engineered for improved xylose utilization. the gene tala, which encodes transaldolase from escherichia coli k-12, was cloned and overexpressed in c. acetobutylicum atcc 824. compared with c. acetobutylicum atcc 824 (824-wt), the transformant bearing the e. coli tala gene (824-tal) showed improved ability on xylose utilization and solvents production using xylose as the sole carbon source. during the fermentation of xylose and glucose mixture ... | 2009 | 19695296 |
| the effect of ph and lactose concentration on solvent production from whey permeate using clostridium acetobutylicum. | a study was performed to optimize the production of solvents from whey permeate in batch fermentation using clostridium acetobutylicum p262. fermentations performed at relatively low ph values resulted in high solvent yields and productivities, but lactose utilization was incomplete. at higher ph values, lactose utilization was improved but acid production dominated over solvent production. when operating at the higher ph values, an increase in the initial lactose concentration of the whey perme ... | 1987 | 18576421 |
| the effect of medium composition on the acetone-butanol fermentation in continuous culture. | the effects of growing clostridium acetobutylicum ncib 8052 in a chemostat under conditions of glucose, nh(4) (+), po(4) (3-), mg(2+), and fe(2+) limitation were examined. it was noted that limitation of any major nutrient resulted in the same fermentation pattern. conditions where minor nutrient levels were reduced appeared to stimulate solvent production. under conditions of mg(2+) restriction, a productive solventogenic culture was produced, with a yield of total solvents on glucose of 35.5%. | 1987 | 18576430 |
| development of real-time pcr primer and probe sets for detecting degenerated and non-degenerated forms of the butanol-producing bacterium clostridium acetobutylicum atcc 824. | degeneration is one of the limiting factors in butanol fermentation, and it must be monitored and prevented for stable butanol production. in clostridium acetobutylicum atcc 824, the most well-known butanol-producing microorganism, degeneration is caused by the loss of the psol1 plasmid that carries essential genes involved in solvent production. in this study, we designed two specific primer and probe sets for real-time qpcr (rt-qpcr) detection of c. acetobutylicum atcc 824 (the c. aceto set) a ... | 2010 | 19798472 |
| clostridium acetobutylicum 8-oxoguanine dna glycosylase (ogg) differs from eukaryotic oggs with respect to opposite base discrimination. | during repair of damaged dna, the oxidized base 8-oxoguanine (8-oxog) is removed by 8-oxoguanine-dna glycosylase (ogg) in eukaryotes and most archaea, whereas in most bacteria it is removed by formamidopyrimidine-dna glycosylase (fpg). we report the first characterization of a bacterial ogg, clostridium acetobutylicum ogg (cacogg). like human ogg1 and escherichia coli fpg (ecofpg), cacogg excised 8-oxoguanine. however, unlike hogg1 and ecofpg, cacogg showed little preference for the base opposit ... | 2008 | 18578506 |
| metabolic engineering of clostridium acetobutylicum m5 for highly selective butanol production. | to improve butanol selectivity, clostridium acetobutylicum m5(pimp1e1ab) was constructed by adhe1-ctfab complementation of c. acetobutylicum m5, a derivative strain of c. acetobutylicum atcc 824, which does not produce solvents due to the lack of megaplasmid psol1. the gene products of adhe1-ctfab catalyze the formation of acetoacetate and ethanol/butanol with acid re-assimilation in solventogenesis. effects of the adhe1-ctfab complementation of m5 were studied by batch fermentations under vario ... | 2009 | 19830716 |
| nature and significance of oscillatory behavior during solvent production by clostridium acetobutylicum in continuous culture. | the concurrent production of acids and solvents and the production of acetone during continuous culture in a product-limited chemostat indicated that the culture contained a mixture of acid- and solvent-producing cells. periodic oscillations in the yield of end products and the specific growth rate of the culture were ob served during undisturbed continuous culture at a constant dilution rate. the increased specific growth rate was associated with an increased acid yield and an increase in the r ... | 1988 | 18587752 |
| tertiary structure and characterization of a glycoside hydrolase family 44 endoglucanase from clostridium acetobutylicum. | a gene encoding a glycoside hydrolase family 44 (gh44) protein from clostridium acetobutylicum atcc 824 was synthesized and transformed into escherichia coli. the previously uncharacterized protein was expressed with a c-terminal his tag and purified by nickel-nitrilotriacetic acid affinity chromatography. crystallization and x-ray diffraction to a 2.2-a resolution revealed a triose phosphate isomerase (tim) barrel-like structure with additional greek key and beta-sandwich folds, similar to othe ... | 2010 | 19915043 |
| acetone-butanol-ethanol (abe) fermentation in an immobilized cell trickle bed reactor. | acetone-butanol-ethanol (abe) fermentation was successfully carried out in an immobilized cell trickle bed reactor. the reactor was composed of two serial columns packed with clostridium acetobutylicum atcc 824 entrapped on the surface of natural sponge segments at a cell loading in the range of 2.03-5.56 g dry cells/g sponge. the average cell loading was 3.58 g dry cells/g sponge. batch experiments indicated that a critical ph above 4.2 is necessary for the initiation of cell growth. one of the ... | 1989 | 18588047 |
| crystal structure of nadh:rubredoxin oxidoreductase from clostridium acetobutylicum: a key component of the dioxygen scavenging system in obligatory anaerobes. | | 2010 | 20017214 |
| the [fefe]-hydrogenase maturase hydf from clostridium acetobutylicum contains a co and cn- ligated iron cofactor. | biosynthesis of the [fefe] hydrogenases active site (h-cluster) requires three maturation factors whose respective roles are not understood yet. the clostridial maturation enzymes (cahyde, cahydf and cahydg) were homologously overexpressed in their native host clostridium acetobutylicum. cahydf was able to activate chlamydomonas reinhardtii [fefe] hydrogenase apoprotein (crhyda1(apo)) to almost 100% compared to the native specific hydrogen evolution activity. based on electron paramagnetic reson ... | 2010 | 20018187 |
| crystallization and preliminary x-ray analysis of nadh:rubredoxin oxidoreductase from clostridium acetobutylicum. | nadh:rubredoxin oxidoreductase (nror), an o(2)-inducible protein, is a versatile electron donor for scavengers of o(2) and reactive oxygen species (ros) in clostridium acetobutylicum. recombinant nror was overexpressed in escherichia coli and purified to homogeneity; it was subsequently crystallized using the sitting-drop vapour-diffusion method at 293 k. preliminary crystallographic analysis revealed that the crystals belonged to space group p4(1)22 or p4(3)22, with unit-cell parameters a = b = ... | 2010 | 20057062 |
| characterization of an immobilized cell, trickle bed reactor during long term butanol (abe) fermentation. | acetone-butanol-ethanol (abe) fermentation was performed continuously in an immobilized cell, trickle bed reactor for 54 days without, degeneration by maintaining the ph above 4.3. column clogging was minimized by structured packing of immobilization matrix. the reactor contained two serial glass columns packed with clostridium acetobutylicum adsorbed on 12- and 20-in.-long polyester sponge strips at total flow rates between 38 and 98.7 ml/h. cells were initially grown at 20 g/l glucose resultin ... | 1990 | 18595069 |
| screening and characterization of butanol-tolerant micro-organisms. | poor butanol tolerance of solventogenic stains directly limits their butanol production during industrial-scale fermentation process. this study was performed to search for micro-organisms possessing elevated tolerance to butanol. | 2010 | 20156308 |
| measurement and regulation of the culture reduction state in clostridium acetobutylicum. | with a constant glucose feed concentration, the change in the continuous culture dillution rate resulted in an altered fermentation profile and the cellular nadh content. the cultures growing at high dillution rates demonstrated an oxidative metabolism low nadh and butanol concentrations. the low specific nadh flourescence (f/x) at high butanol production rates suggested that a rapid regeneration of nadh to nad is essential for a high solventogenic culture activity. the culture florescence and b ... | 1991 | 18600748 |
| the formation of lactic acid by clostridium acetobutylicum (weizmann). | | 1947 | 20240450 |
| continuous acetone-butanol-ethanol (abe) fermentation using immobilized cells of clostridium acetobutylicum in a packed bed reactor and integration with product removal by pervaporation. | an integrated solvent (abe) fermentation and product removal process was investigated. a stable solvent productivity of 3.5 g/l h was achieved by using cells of clostridium acetobutylicum immobilized onto a packed bed of bonechar, coupled with continuous product removal by pervaporation. using a concentrated feed solution containing lactose at 130g/l, a lactose value of 97.9% was observed. the integrated fermentation and product removal system, with recycling of the treated fermentor effluent co ... | 1991 | 18604810 |