Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| analysis of the elements of catabolite repression in clostridium acetobutylicum atcc 824. | the ptsh gene, encoding the phosphotransferase protein hpr, from clostridium acetobutylicum atcc 824 was identified from the genome sequence, cloned and shown to complement a ptsh mutant of escherichia coli. the deduced protein sequence shares significant homology with hpr proteins from other low-gc gram-positive bacteria, although the highly conserved sequence surrounding the ser-46 phosphorylation site is not well preserved in the clostridial protein. nevertheless, the hpr was phosphorylated i ... | 2003 | 14593248 |
| cloning, characterization, and functional expression of the klebsiella oxytoca xylodextrin utilization operon (xyntb) in escherichia coli. | escherichia coli is being developed as a biocatalyst for bulk chemical production from inexpensive carbohydrates derived from lignocellulose. potential substrates include the soluble xylodextrins (xyloside, xylooligosaccharide) and xylobiose that are produced by treatments designed to expose cellulose for subsequent enzymatic hydrolysis. adjacent genes encoding xylobiose uptake and hydrolysis were cloned from klebsiella oxytoca m5a1 and are functionally expressed in ethanologenic e. coli. the xy ... | 2003 | 14532050 |
| overexpression of groesl in clostridium acetobutylicum results in increased solvent production and tolerance, prolonged metabolism, and changes in the cell's transcriptional program. | dna array and western analyses were used to examine the effects of groesl overexpression and host-plasmid interactions on solvent production in clostridium acetobutylicum atcc 824. strain 824(pgroe1) was created to overexpress the groesl operon genes from a clostridial thiolase promoter. the growth of 824(pgroe1) was inhibited up to 85% less by a butanol challenge than that of the control strain, 824(psos95del). overexpression of groesl resulted in increased final solvent titers 40% and 33% high ... | 2003 | 12902291 |
| development of a sensitive gene expression reporter system and an inducible promoter-repressor system for clostridium acetobutylicum. | a sensitive gene expression reporter system was developed for clostridium acetobutylicum atcc 824 by using a customized gusa expression cassette. in discontinuous cultures, time course profiles of beta-glucuronidase specific activity reflected adequately in vivo dynamic up- and down-regulation of acidogenesis- and/or solventogenesis-associated promoter expression in c. acetobutylicum. furthermore, a new inducible gene expression system was developed in c. acetobutylicum, based on the staphylococ ... | 2003 | 12902297 |
| 2,4,6-trinitrotoluene reduction by an fe-only hydrogenase in clostridium acetobutylicum. | the role of hydrogenase on the reduction of 2,4,6-trinitrotoluene (tnt) in clostridium acetobutylicum was evaluated. an fe-only hydrogenase was isolated and identified by using tnt reduction activity as the selection basis. the formation of hydroxylamino intermediates by the purified enzyme corresponded to expected products for this reaction, and saturation kinetics were determined with a k(m) of 152 micro m. comparisons between the wild type and a mutant strain lacking the region encoding an al ... | 2003 | 12620841 |
| translational selection is operative for synonymous codon usage in clostridium perfringens and clostridium acetobutylicum. | here, the codon usage patterns of two clostridium species (clostridium perfringens and clostridium acetobutylicum) are reported. these prokaryotes are characterized by a strong mutational bias towards a+t, a striking excess of coding sequences and purine-rich leading strands of replication, strong gc-skews and a high frequency of genomic rearrangements. as expected, it was found that the mutational bias dominates codon usage but there is some variation of synonymous codon choices among genes in ... | 2003 | 12686628 |
| expression of a cloned cyclopropane fatty acid synthase gene reduces solvent formation in clostridium acetobutylicum atcc 824. | the cyclopropane fatty acid synthase gene (cfa) of clostridium acetobutylicum atcc 824 was cloned and overexpressed under the control of the clostridial ptb promoter. the function of the cfa gene was confirmed by complementation of an escherichia coli cfa-deficient strain in terms of fatty acid composition and growth rate under solvent stress. constructs expressing cfa were introduced into c. acetobutylicum hosts and cultured in rich glucose broth in static flasks without ph control. overexpress ... | 2003 | 12732555 |
| molecular cloning of the gene for 2,6-beta-d-fructan 6-levanbiohydrolase from streptomyces exfoliatus f3-2. | the gene encoding a 2,6-beta-d-fructan 6-levanbiohydrolase (lf2ase) (ec 3.2.1.64) that converts levan into levanbiose was cloned from the genomic dna of streptomyces exfoliatus f3-2. the gene encoded a signal peptide of 37 amino acids and a mature protein of 482 amino acids with a total length of 1560 bp and was successfully expressed in escherichia coli. the similarities of primary structure were observed with levanases from clostridium acetobutylicum, bacillus subtilis, b. stearothermophilus ( ... | 2003 | 12586402 |
| characterization of the cipa scaffolding protein and in vivo production of a minicellulosome in clostridium acetobutylicum. | the cipa gene encoding the clostridium acetobutylicum scaffolding protein cipa was cloned and expressed in escherichia coli. cipa contains an n-terminal signal peptide, a family 3a cellulose-binding domain (cbd), five type i cohesin domains, and six hydrophilic domains. the uniqueness of cipa lies in the enchainment of cohesin domains that are all separated by a hydrophilic domain. affinity-purified cipa was used in equilibrium-binding experiments to characterize the interaction of cipa with cry ... | 2003 | 12533485 |
| the effect of carbon sources and lactate dehydrogenase deletion on 1,2-propanediol production in escherichia coli. | in previous studies, we showed that cofactor manipulations can potentially be used as a tool in metabolic engineering. in this study, sugars similar to glucose, that can feed into glycolysis and pyruvate production, but with different oxidation states, were used as substrates. this provided a simple way of testing the effect of manipulating the nadh/nad+ ratio or the availability of nadh on the metabolic patterns of escherichia coli under anaerobic conditions and on the production of 1,2-propane ... | 2003 | 12545384 |
| characterization and development of two reporter gene systems for clostridium acetobutylicum. | the use of lacz from thermoanaerobacterium thermosulfurigenes (encoding beta-galactosidase) and lucb from photinus pyralis (encoding luciferase) as reporter genes in clostridium acetobutylicum was analyzed with promoters of genes required for solventogenesis and acidogenesis. both systems proved to be well suited and allowed the detection of differences in promoter strength at least up to 100-fold. the luciferase assay could be performed much faster and comes close to online measurement. reseque ... | 2004 | 14766557 |
| genes malh and pagl of clostridium acetobutylicum atcc 824 encode nad+- and mn2+-dependent phospho-alpha-glucosidase(s). | the genome of clostridium acetobutylicum 824 contains two genes encoding nad+, mn2+, and dithiothreitol-dependent phospho-alpha-glucosidases that can be assigned to family 4 of the glycosylhydrolase superfamily. the two genes, designated malh (maltose 6-phosphate hydrolase) and pagl (phospho-alpha-glucosidase), respectively, reside in separate operons that also encode proteins of the phosphoenolpyruvate-dependent:sugar phosphotransferase system. c. acetobutylicum grows on a variety of alpha-link ... | 2004 | 14570887 |
| production of heterologous and chimeric scaffoldins by clostridium acetobutylicum atcc 824. | clostridium acetobutylicum atcc 824 converts sugars and various polysaccharides into acids and solvents. this bacterium, however, is unable to utilize cellulosic substrates, since it is able to secrete very small amounts of cellulosomes. to promote the utilization of crystalline cellulose, the strategy we chose aims at producing heterologous minicellulosomes, containing two different cellulases bound to a miniscaffoldin, in c. acetobutylicum. a first step toward this goal describes the productio ... | 2004 | 14679247 |
| thermostable xylanase10b from clostridium acetobutylicum atcc824. | the clostridium acetobutylicum xylanase gene xyn10b (cap0116) was cloned from the type strain atcc 824, whose genome was recently sequenced. the nucleotide sequence of c. acetobutylicum xyn10b encodes a 318-amino acid protein. xyn10b consists of a single catalytic domain that belongs to family 10 of glycosyl hydrolases. the enzyme was purified from recombinant escherichia coli. the xyn10b enzyme was highly active toward birchwood xylan, oat-spelt xylan, and moderately active toward avicel, carbo ... | 2004 | 15252718 |
| comparative analysis of gene expression among low g+c gram-positive genomes. | we present a comparative analysis of predicted highly expressed (phx) genes in the low g+c gram-positive genomes of bacillus subtilis, bacillus halodurans, listeria monocytogenes, listeria innocua, lactococcus lactis, streptococcus pyogenes, streptococcus pneumoniae, staphylococcus aureus, clostridium acetobutylicum, and clostridium perfringens. most enzymes acting in glycolysis and fermentation pathways are phx in these genomes, but not those involved in the tca cycle and respiration, suggestin ... | 2004 | 15069198 |
| transcriptional analysis of spo0a overexpression in clostridium acetobutylicum and its effect on the cell's response to butanol stress. | spo0a is the regulator of stationary-phase events and is required for transcription of solvent formation genes in clostridium acetobutylicum. in order to elucidate the role of spo0a in differentiation, we performed transcriptional analysis of 824(pmspoa) (a spo0a-overexpressing c. acetobutylicum strain with enhanced sporulation) against a plasmid control strain. dna microarray data were contrasted to data from a spo0a knockout strain (sko1) that neither sporulates nor produces solvents. transcri ... | 2004 | 15028679 |
| 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 |
| initiation of endospore formation in clostridium acetobutylicum. | endospore formation in bacilli and clostridia shows remarkable similarities in morphology as well as in physiological and molecular biological cellular events. major differences are the formation of clostridial stage cells and granulose accumulation in clostridia. in both genera, a cascade of sigma factors is activated after septation (by help of sigma(h) and spo0a approximately p) in the sequence sigma(f), sigma(e), sigma(g), and sigma(k). of these, sigma(f) and sigma(g) are active inside the f ... | 2004 | 16701502 |
| substrate-induced production and secretion of cellulases by clostridium acetobutylicum. | clostridium acetobutylicum atcc 824 is a solventogenic bacterium that grows heterotrophically on a variety of carbohydrates, including glucose, cellobiose, xylose, and lichenan, a linear polymer of beta-1,3- and beta-1,4-linked beta-d-glucose units. c. acetobutylicum does not degrade cellulose, although its genome sequence contains several cellulase-encoding genes and a complete cellulosome cluster of cellulosome genes. in the present study, we demonstrate that a low but significant level of ind ... | 2004 | 15345405 |
| h2-producing bacterial communities from a heat-treated soil inoculum. | hydrogen gas (approximately 60% h(2)) was produced in a continuous flow bioreactor inoculated with heat-treated soil, and fed synthetic wastewater containing glucose (9.5 g l(-1)). the ph in the bioreactor was maintained at 5.5 to inhibit consumption of h(2) by methanogens. the objective of this study was to characterize bacterial communities in the reactor operated under two different hydraulic retention times (hrts of 30-h and 10-h) and temperatures (30 degrees c and 37 degrees c). at 30-h hrt ... | 2004 | 15558274 |
| identification and functional analysis of dtdp-glucose-4,6-dehydratase gene and its linked gene cluster in an aminoglycoside antibiotics producer of streptomyces tenebrarius h6. | streptomyces tenebrarius h6 produces a variety of aminoglycoside antibiotics, such as apramycin, tobramycin, and kanamycin b. primers were designed according to the highly conserved sequences of the dtdp-glucose-4,6-dehydratase genes, and a 0.6-kb pcr product was obtained from s. tenebrarius h6 genomic dna. with the 0.6-kb pcr product as a probe, a bamhi 7.0-kb fragment was isolated. dna sequence analysis of the 7.0-kb fragment revealed four orfs and an incomplete orf. in search of databases, th ... | 2004 | 15297914 |
| identification of o2-induced peptides in an obligatory anaerobe, clostridium acetobutylicum. | clostridium acetobutylicum dsm792 (=atcc824), a solvent producing obligate anaerobe, grew well after a shift in growth conditions from anoxic to microoxic at the mid exponential phase. in two-dimensional gel electrophoresis, a spot migrating at 45 kda and three spots at 23 kda accumulated after 30 min of flushing with 5% o(2)/95% n(2). based on peptide mass fingerprints, the 45 kda polypeptide was determined to be np_347663 (a-type flavoprotein homologue) and the 23 kda polypeptides were determi ... | 2004 | 15280011 |
| a rubrerythrin-like oxidative stress protein of clostridium acetobutylicum is encoded by a duplicated gene and identical to the heat shock protein hsp21. | comparison of the n-terminus of the heat shock protein hsp21 of clostridium acetobutylicum with proteins predicted to be encoded by the genome of this bacterium revealed that this stress protein is encoded by two almost identical open reading frames cac3597 and cac3598. these genes encode a rubrerythrin-like protein with the rubredoxin-like fes4 domain at the n-terminus and the ferritin-like diiron domain (rubrerythrin domain) at the c-terminus. thus, the order of the two putative functional dom ... | 2004 | 15336429 |
| sequencing and expression of the gene encoding the clostridium stercorarium beta-xylosidase xyl43b in escherichia coli. | the clostridium stercorarium f-9 xyl43b gene encoding the beta-xylosidase xyl43b consists of an open reading frame of 1,491 nucleotides that encodes a putative protein, classified in family 43, of 497 amino acids with a predicted molecular weight of 56,355. the deduced amino acid sequence of xyl43b has sequence similarity with beta-xylosidases from bacteriodes thetaiotaomicron (57% sequence identity), prevotella ruminicola (45%), streptomyces coelicolor (40%), and clostridium acetobutylicum (36% ... | 2004 | 15056894 |
| transcriptional organization of the clostridium acetobutylicum genome. | prokaryotic genes are frequently organized in multicistronic operons (or transcriptional units, tus), and usually the regulatory motifs for the whole tu are located upstream of the first tu gene. although the number of sequenced genomes has increased dramatically, experimental information on tu organization is extremely limited. even for organisms as extensively studied as escherichia coli and bacillus subtilis, tu annotation is far from complete. it therefore becomes imperative to rely on compu ... | 2004 | 15060177 |
| analysis of orthologous hrca genes in escherichia coli and bacillus subtilis. | the hrca gene codes for a transcriptional repressor protein interacting with the circe operator thereby reducing expression of the groe operon of more than 120 bacterial species. at least in bacillus subtilis, the activity of the hrca protein is modulated by the groe chaperonin system. we amplified the hrca gene from five different bacterial species and analyzed its activity in escherichia coli and bacillus subtilis. while those from clostridium acetobutylicum and staphylococcus aureus turned ou ... | 2004 | 15109714 |
| transcriptional analysis of butanol stress and tolerance in clostridium acetobutylicum. | the effects of challenges with low (0.25%, vol/vol) and high (0.75%) concentrations of butanol on the growth, glucose metabolism, product formation, and transcriptional program of the solvent-tolerant clostridium acetobutylicum strain 824(pgroe1) and the plasmid control strain 824(psos95del) were used to study solvent tolerance and stress response. strain 824(pgroe1) was generated by groesl overexpression. the growth of 824(pgroe1) was less inhibited than that of 824(psos95del), and 824(pgroe1) ... | 2004 | 15028684 |
| continuous production of butanol by clostridium acetobutylicum immobilized in a fibrous bed bioreactor. | we explored the influence of dilution rate and ph in continuous cultures of clostridium acetobutylicum. a 200-ml fibrous bed bioreactor was used to produce high cell density and butyrate concentrations at ph 5.4 and 35degreesc. by feeding glucose and butyrate as a cosubstrate, the fermentation was maintained in the solventogenesis phase, and the optimal butanol productivity of 4.6 g/(l h) and a yield of 0.42 g/g were obtained at a dilution rate of 0.9 h-1 and ph 4.3. compared to the conventional ... | 2004 | 15054240 |
| characterization of thermostable xyn10a enzyme from mesophilic clostridium acetobutylicum atcc 824. | a thermostable xylanase gene, xyn10a (cap0053), was cloned from clostridium acetobutylicum atcc 824. the nucleotide sequence of the c. acetobutylicum xyn10a gene encoded a 318-amino-acid, single-domain, family 10 xylanase, xyn10a, with a molecular mass of 34 kda. xyn10a exhibited extremely high (92%) amino acid sequence identity with xyn10b (cap0116) of this strain and had 42% and 32% identity with the catalytic domains of rhodothermus marinus xylanase i and thermoascus aurantiacus xylanase i, r ... | 2005 | 15765251 |
| a wide host-range metagenomic library from a waste water treatment plant yields a novel alcohol/aldehyde dehydrogenase. | using dna obtained from the metagenome of an anaerobic digestor in a waste water treatment plant, we constructed a gene library cloned in the wide host-range cosmid plafr3. one cosmid enabled rhizobium leguminosarum to grow on ethanol as sole carbon and energy source, this being due to the presence of a gene, termed adhemeta. the adhemeta protein most closely resembles the adhe alcohol dehydrogenase of clostridium acetobutylicum, where it catalyses the formation of ethanol and butanol in a two-s ... | 2005 | 16309390 |
| 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 |
| intracellular butyryl phosphate and acetyl phosphate concentrations in clostridium acetobutylicum and their implications for solvent formation. | it has been suggested (l. h. harris, r. p. desai, n. e. welker, and e. t. papoutsakis, biotechnol. bioeng. 67:1-11, 2000) that butyryl phosphate (bup) is a regulator of solventogenesis in clostridium acetobutylicum. here, we determined bup and acetyl phosphate (acp) levels in fermentations of c. acetobutylicum wild type (wt), degenerate strain m5, a butyrate kinase (buk) mutant, and a phosphotransacetylase (pta) mutant. a sensitive method was developed to measure bup and acp in the same sample. ... | 2005 | 15640230 |
| 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 |
| analyses of enzyme ii gene mutants for sugar transport and heterologous expression of fructokinase gene in corynebacterium glutamicum atcc 13032. | corynebacterium glutamicum atcc 13032 has four enzyme ii (eii) genes of the phosphotransferase system in its genome encoding transporters for sucrose, glucose, fructose, and an unidentified eii. to analyze the function of these eii genes, they were inactivated via homologous recombination and the resulting mutants characterized for sugar utilization. whereas the sucrose eii was the only transport system for sucrose in c. glutamicum, fructose and glucose were each transported by a second transpor ... | 2005 | 15766777 |
| expression of abrb310 and sinr, and effects of decreased abrb310 expression on the transition from acidogenesis to solventogenesis, in clostridium acetobutylicum atcc 824. | the transcription factors sinr and abrb are involved in the control of sporulation initiation in bacillus subtilis. we identified a single homologue to sinr and three highly similar homologues to abrb, designated abrb310, abrb1941, and abrb3647, in clostridium acetobutylicum atcc 824. using reporter vectors, we showed that the promoters of abrb1941 and abrb3647 were not active under the growth conditions tested. the abrb310 promoter was strongly active throughout growth and exhibited a transient ... | 2005 | 15812030 |
| homologous and heterologous overexpression in clostridium acetobutylicum and characterization of purified clostridial and algal fe-only hydrogenases with high specific activities. | clostridium acetobutylicum atcc 824 was selected for the homologous overexpression of its fe-only hydrogenase and for the heterologous expressions of the chlamydomonas reinhardtii and scenedesmus obliquus hyda1 fe-only hydrogenases. the three strep tag ii-tagged fe-only hydrogenases were isolated with high specific activities by two-step column chromatography. the purified algal hydrogenases evolve hydrogen with rates of around 700 micromol h(2) min(-1) mg(-1), while hyda from c. acetobutylicum ... | 2005 | 15870373 |
| genetic characterization of the beta-glucuronidase enzyme from a human intestinal bacterium, ruminococcus gnavus. | beta-glucuronidase activity (encoded by the gus gene) has been characterized for the first time from ruminococcus gnavus e1, an anaerobic bacterium belonging to the dominant human gut microbiota. beta-glucuronidase activity plays a major role in the generation of toxic and carcinogenic metabolites in the large intestine, as well as in the absorption and enterohepatic circulation of many aglycone residues with protective effects, such as lignans, flavonoids, ceramide and glycyrrhetinic acid, that ... | 2005 | 16000722 |
| transcriptional program of early sporulation and stationary-phase events in clostridium acetobutylicum. | dna microarray analysis of clostridium acetobutylicum was used to examine the genomic-scale gene expression changes during the shift from exponential-phase growth and acidogenesis to stationary phase and solventogenesis. self-organizing maps were used to identify novel expression patterns of functional gene classes, including aromatic and branched-chain amino acid synthesis, ribosomal proteins, cobalt and iron transporters, cobalamin biosynthesis, and lipid biosynthesis. the majority of psol1 me ... | 2005 | 16199581 |
| genomic analysis of the protein secretion systems in clostridium acetobutylicum atcc 824. | consistent information about protein secretion in gram-positive bacteria is essentially restricted to the model organism bacillus subtilis. among genome-sequenced clostridia, clostridium acetobutylicum has been the most extensively studied from a physiological point of view and is the organism for which the largest variety of molecular biology tools have been developed. following in silico analyses, both secreted proteins and protein secretion systems were identified. the tat (twin arginine tran ... | 2005 | 15950297 |
| heterologous production, assembly, and secretion of a minicellulosome by clostridium acetobutylicum atcc 824. | the gene man5k encoding the mannanase man5k from clostridium cellulolyticum was cloned alone or as an operon with the gene cipc1 encoding a truncated scaffoldin (minicipc1) of the same origin in the solventogenic clostridium acetobutylicum. the expression of the heterologous gene(s) was under the control of a weakened thiolase promoter pthl. the recombinant strains of the solventogenic bacterium were both found to secrete active man5k in the range of milligrams per liter. in the case of the stra ... | 2005 | 15746321 |
| metabolic engineering of clostridium acetobutylicum for the industrial production of 1,3-propanediol from glycerol. | clostridium butyricum is to our knowledge the best natural 1,3-propanediol producer from glycerol and the only microorganism identified so far to use a coenzyme b12-independent glycerol dehydratase. however, to develop an economical process of 1,3-propanediol production, it would be necessary to improve the strain by a metabolic engineering approach. unfortunately, no genetic tools are currently available for c. butyricum and all our efforts to develop them have been so far unsuccessful. to obta ... | 2005 | 16095939 |
| biochemical characterization of trinitrotoluene transforming oxygen-insensitive nitroreductases from clostridium acetobutylicum atcc 824. | the genes that encode oxygen-insensitive nitroreductases from clostridium acetobutylicum possessing 2,4,6-trinitrotoluene (tnt) transformation activity were cloned, sequenced and characterized. the gene products nita (mw 31 kda) and nitb (mw 23 kda) were purified to homogeneity. the nita and nitb are oxygen-insensitive nitroreductases comprised of a single nitroreductase domain. nita and nitb enzymes show spectral characteristics similar to flavoproteins. the biochemical characteristics of nita ... | 2005 | 16187099 |
| secretory production of biologically active rat interleukin-2 by clostridium acetobutylicum dsm792 as a tool for anti-tumor treatment. | the search for effective means of selectively delivering high therapeutic doses of anti-cancer agents to tumors has explored a variety of systems in the last decade. the ability of intravenously injected clostridial spores to infiltrate and thence selectively germinate in the hypoxic regions of solid tumors is exquisitely specific, making this system an interesting addition to the anti-cancer therapy arsenal. to increase the number of therapeutic proteins potentially useful for cancer treatment ... | 2005 | 15869963 |
| 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 |
| microbial conversion of glycerol to 1,3-propanediol: physiological comparison of a natural producer, clostridium butyricum vpi 3266, and an engineered strain, clostridium acetobutylicum dg1(pspd5). | clostridium acetobutylicum is not able to grow on glycerol as the sole carbon source since it cannot reoxidize the excess of nadh generated by glycerol catabolism. nevertheless, when the pspd5 plasmid, carrying the nadh-consuming 1,3-propanediol pathway from c. butyricum vpi 3266, was introduced into c. acetobutylicum dg1, growth on glycerol was achieved, and 1,3-propanediol was produced. in order to compare the physiological behavior of the recombinant c. acetobutylicum dg1(pspd5) strain with t ... | 2006 | 16391030 |
| regulation of toxin and bacteriocin gene expression in clostridium by interchangeable rna polymerase sigma factors. | the production of major extracellular toxins by pathogenic strains of clostridium botulinum, clostridium tetani and clostridium difficile, and a bacteriocin by clostridium perfringens is dependent on a related group of rna polymerase sigma-factors. these sigma-factors (botr, tetr, tcdr and uvia) were shown to be sufficiently similar that they could substitute for one another in in vitro dna binding and run-off transcription experiments. in cells, however, the sigma-factors fell into two subclass ... | 2006 | 16677313 |
| butanol production from corn fiber xylan using clostridium acetobutylicum. | acetone, butanol, and ethanol (abe) were produced from corn fiber arabinoxylan (cfax) and cfax sugars (glucose, xylose, galactose, and arabinose) using clostridium acetobutylicum p260. in mixed sugar (glucose, xylose, galactose, and arabinose) fermentation, the culture preferred glucose and arabinose over galactose and xylose. under the experimental conditions, cfax (60 g/l) was not fermented until either 5 g/l xylose or glucose plus xylanase enzyme were added to support initial growth and ferme ... | 2006 | 16739948 |
| transcription of the pst operon of clostridium acetobutylicum is dependent on phosphate concentration and ph. | the pst operon of clostridium acetobutylicum atcc 824 comprises five genes, psts, pstc, psta, pstb, and phou, and shows a gene architecture identical to that of escherichia coli. deduced proteins are predicted to represent a high-affinity phosphate-specific abc (atp-binding cassette) transport system (pst) and a protein homologous to phou, a negative phosphate regulon regulator. we analyzed the expression patterns of the pst operon in p(i)-limited chemostat cultures during acid production at ph ... | 2006 | 16855236 |
| 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 |
| the rubrerythrin-like protein hsp21 of clostridium acetobutylicum is a general stress protein. | the small heat shock protein hsp21 of clostridium acetobutylicum was recently identified as a rubrerythrin-like protein with a rubredoxin-like fes(4) domain at the n-terminus and a ferritin-like diiron domain at the c-terminus. here, we report that the two identical tandem genes rbr3a and rbr3b, which encode the heat shock protein hsp21, show the transcription pattern of general stress genes. northern blot analysis indicated that the transcription of the rbr3ab operon is induced by various envir ... | 2006 | 16463182 |
| functional studies of [fefe] hydrogenase maturation in an escherichia coli biosynthetic system. | maturation of [fefe] hydrogenases requires the biosynthesis and insertion of the catalytic iron-sulfur cluster, the h cluster. two radical s-adenosylmethionine (sam) proteins proposed to function in h cluster biosynthesis, hydef and hydg, were recently identified in the hydef-1 mutant of the green alga chlamydomonas reinhardtii (m. c. posewitz, p. w. king, s. l. smolinski, l. zhang, m. seibert, and m. l. ghirardi, j. biol. chem. 279:25711-25720, 2004). previous efforts to study [fefe] hydrogenas ... | 2006 | 16513746 |
| 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 |
| 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 | |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| targeted gene disruption by use of a group ii intron (targetron) vector in clostridium acetobutylicum. | 2007 | 17971808 | |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| activity of abrb310 promoter in wild type and spo0a-deficient strains of clostridium acetobutylicum. | in clostridium acetobutylicum, abrb310 is transcribed from two transcription start sites (designated a1 and a2) forming an abundant large, and a five- to tenfold less abundant small transcript, respectively throughout exponential, acidogenic growth and early in the transitional period to stationary, solventogenic growth. beta-galactosidase reporter vectors were constructed to compare the transcriptional activity of the entire abrb310 promoter and the a1 and a2 transcription start sites individua ... | 2008 | 18347825 |
| 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 |
| 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 |
| 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 |
| fermentative butanol production: bulk chemical and biofuel. | clostridium acetobutylicum is an anaerobic, spore-forming bacterium with the ability to ferment starch and sugars into solvents. in the past, it has been used for industrial production of acetone and butanol, until cheap crude oil rendered petrochemical synthesis more economically feasible. both economic (price of crude oil) and environmental aspects (carbon dioxide emissions) have caused the pendulum to swing back again. molecular biology has allowed a detailed understanding of genes and enzyme ... | 2008 | 18378605 |
| x-ray structure of the [fefe]-hydrogenase maturase hyde from thermotoga maritima. | maturation of the [fefe]-hydrogenase active site depends on at least the expression of three gene products called hyde, hydf, and hydg. we have solved the high resolution structure of recombinant, reconstituted s-adenosine-l-methionine-dependent hyde from thermotoga maritima. besides the conserved [fe(4)s(4)] cluster involved in the radical-based reaction, this hyde was reported to have a second [fe(4)s(4)] cluster coordinated by three cys residues. however, in our crystals, depending on the rec ... | 2008 | 18400755 |
| 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 |
| perr acts as a switch for oxygen tolerance in the strict anaerobe clostridium acetobutylicum. | clostridia belong to those bacteria which are considered as obligate anaerobe, e.g. oxygen is harmful or lethal to these bacteria. nevertheless, it is known that they can survive limited exposure to air, and often eliminate oxygen or reactive derivatives via nad(p)h-dependent reduction. this system does apparently contribute to survival after oxidative stress, but is insufficient to establish long-term tolerance of aerobic conditions. here we show that manipulation of the regulatory mechanism of ... | 2008 | 18430081 |
| [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 |
| 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 |
| increased productivity of clostridium acetobutylicum fermentation of acetone, butanol, and ethanol by pervaporation through supported ionic liquid membrane. | pervaporation proved to be one of the best methods to remove solvents out of a solvent producing clostridium acetobutylicum culture. by using an ionic liquid (il)-polydimethylsiloxane (pdms) ultrafiltration membrane (pore size 60 nm), we could guarantee high stability and selectivity during all measurements carried out at 37 degrees c. overall solvent productivity of fermentation connected with continuous product removal by pervaporation was 2.34 g l(-1) h(-1). the supported ionic liquid membran ... | 2008 | 18231789 |
| 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 |
| 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 |
| development and application of flow-cytometric techniques for analyzing and sorting endospore-forming clostridia. | the study of microbial heterogeneity at the single-cell level is a rapidly growing area of research in microbiology and biotechnology due to its significance in pathogenesis, environmental biology, and industrial biotechnologies. however, the tools available for efficiently and precisely probing such heterogeneity are limited for most bacteria. here we describe the development and application of flow-cytometric (fc) and fluorescence-assisted cell-sorting techniques for the study of endospore-for ... | 2008 | 18931289 |
| genome-scale reconstruction and in silico analysis of the clostridium acetobutylicum atcc 824 metabolic network. | to understand the metabolic characteristics of clostridium acetobutylicum and to examine the potential for enhanced butanol production, we reconstructed the genome-scale metabolic network from its annotated genomic sequence and analyzed strategies to improve its butanol production. the generated reconstructed network consists of 502 reactions and 479 metabolites and was used as the basis for an in silico model that could compute metabolic and growth performance for comparison with fermentation d ... | 2008 | 18758767 |
| genome-scale model for clostridium acetobutylicum: part ii. development of specific proton flux states and numerically determined sub-systems. | a regulated genome-scale model for clostridium acetobutylicum atcc 824 was developed based on its metabolic network reconstruction. to aid model convergence and limit the number of flux-vector possible solutions (the size of the phenotypic solution space), modeling strategies were developed to impose a new type of constraint at the endo-exo-metabolome interface. this constraint is termed the specific proton flux state, and its use enabled accurate prediction of the extracellular medium ph during ... | 2008 | 18767191 |
| genome-scale model for clostridium acetobutylicum: part i. metabolic network resolution and analysis. | a genome-scale metabolic network reconstruction for clostridium acetobutylicum (atcc 824) was carried out using a new semi-automated reverse engineering algorithm. the network consists of 422 intracellular metabolites involved in 552 reactions and includes 80 membrane transport reactions. the metabolic network illustrates the reliance of clostridia on the urea cycle, intracellular l-glutamate solute pools, and the acetylornithine transaminase for amino acid biosynthesis from the 2-oxoglutarate p ... | 2008 | 18767192 |
| 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 |
| raman spectroscopy of charge transfer interactions between single wall carbon nanotubes and [fefe] hydrogenase. | we report a raman spectroscopy study of charge transfer interactions in complexes formed by single-walled carbon nanotubes (swnts) and [fefe] hydrogenase i (cahydi) from clostridium acetobutylicum. the choice of raman excitation wavelength and sample preparation conditions allows differences to be observed for complexes involving metallic (m) and semiconducting (s) species. adsorbed cahydi can reversibly inject electronic charge into the lumos of s-swnts, while charge can be injected and removed ... | 2008 | 19082027 |
| 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 |
| [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 |
| 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 |